Clean Air Fine Particle Implementation Rule
[Federal Register: April 25, 2007 (Volume 72, Number 79)]
[Rules and Regulations]
[Page 20585-20667]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]
[DOCID:fr25ap07-10]
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ENVIRONMENTAL PROTECTION AGENCY
40 CFR Part 51
[EPA-HQ-OAR-2003-0062; FRL-8295-2]
RIN 2060-AK74
Clean Air Fine Particle Implementation Rule
AGENCY: Environmental Protection Agency (EPA).
ACTION: Final rule.
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SUMMARY: This final action provides rules and guidance on the Clean Air
Act (CAA) requirements for State and Tribal plans to implement the 1997
fine particle (PM2.5) national ambient air quality standards
(NAAQS). Fine particles and precursor pollutants are emitted by a wide
range of sources, including power plants, cars, trucks, industrial
sources, and other burning or combustion-related activities. Health
effects that have been associated with exposure to PM2.5
include premature death, aggravation of heart and lung disease, and
asthma attacks. Those particularly sensitive to PM2.5 exposure
include older adults, people with heart and lung disease, and children.
Air quality designations became effective on April 5, 2005 for 39
areas (with a total population of 90 million) that were not attaining
the 1997 PM2.5 standards. By April 5, 2008, each State
having a nonattainment area must submit to EPA an attainment
demonstration and adopted regulations ensuring that the area will
attain the standards as expeditiously as practicable, but no later than
2015. This rule and preamble describe the requirements that States and
Tribes must meet in their implementation plans for attainment of the
1997 fine particle NAAQS. (Note that this rule does not include final
PM2.5 requirements for the new source review (NSR) program;
the final NSR rule will be issued at a later date.)
DATES: This rule is effective on May 29, 2007.
ADDRESSES: The EPA has established a docket for this action under
Docket ID EPA-HQ-OAR-2003-0062. All documents relevant to this action
are listed in the Federal docket management system at
http://www.regulations.gov. Although listed in the index, some information is
not publicly available (e.g. Confidential Business Information or other
information whose disclosure is restricted by statute). Certain other
material, such as copyrighted material, is not placed on the Internet
and will be publicly available only in hard copy form. Publicly
available docket materials are available either electronically through
http://www.regulations.gov or in hard copy format at the EPA Docket Center,
EPA/DC, EPA West, Room 3334, 1301 Constitution Avenue, NW., Washington,
DC. The Public Reading Room is open from 8:30 a.m. to 4:30 p.m., Monday
through Friday, excluding legal holidays. The telephone number for the
Public Reading Room is (202) 566-1744, and the telephone number for the
Office of Air and Radiation Docket and Information Center is (202) 566-
1742. A variety of information and materials related to the fine
particle NAAQS and implementation program are also available on EPA's
Web site: http://www.epa.gov/air/particles.
FOR FURTHER INFORMATION CONTACT: For general information, contact Mr.
Richard Damberg, U.S. Environmental Protection Agency, Office of Air
Quality Planning and Standards, Mail Code C539-01, Research Triangle
Park, NC 27711, phone number (919) 54l-5592 or by e-mail at:
damberg.rich@epa.gov.
SUPPLEMENTARY INFORMATION:
General Information
A. Does this action apply to me?
Entities potentially regulated by this action are State and local
air quality agencies.
B. Where can I get a copy of this document and other related information?
In addition to being available in the docket, an electronic copy of
this final rule will also be available on the World Wide Web. Following
signature by the EPA Administrator, a copy of this final rule will be
posted at http://www.epa.gov/particles/actions.html.
C. How is the preamble organized?
I. Background
II. Elements of the Clean Air Fine Particle Implementation Rule
A. Precursors and Pollutants Contributing to Fine Particle Formation
B. No Classification System
C. Due Dates and Basic Requirements for Attainment Demonstrations
D. Attainment Dates
E. Modeling and Attainment Demonstrations
F. Reasonably Available Control Technology and Reasonably
Available Control Measures
G. Reasonable Further Progress
H. Contingency Measures
I. Transportation Conformity
J. General Conformity
K. Emission Inventory Requirements
L. Condensable Particulate Matter Test Methods and Related Data Issues
M. Improving Source Monitoring
N. Guidance Specific to Tribes
O. Enforcement and Compliance
P. Emergency Episodes
Q. Ambient Monitoring
III. Statutory and Executive Order Reviews
A. Executive Order 12866: Regulatory Planning and Review
B. Paperwork Reduction Act
C. Regulatory Flexibility Act
D. Unfunded Mandates Reform Act
E. Executive Order 13132: Federalism
F. Executive Order 13175: Consultation and Coordination With
Indian Tribal Governments
G. Executive Order 13045: Protection of Children From
Environmental Health and Safety Risks
H. Executive Order 13211: Actions That Significantly Affect
Energy Supply, Distribution, or Use
I. National Technology Transfer Advancement Act
J. Executive Order 12898: Federal Actions To Address
Environmental Justice in Minority Populations and Low-Income Populations
K. Congressional Review Act
L. Petitions for Judicial Review
M. Judicial Review
IV. Statutory Authority
I. Background
Fine particles in the atmosphere are comprised of a complex mixture
of components. Common constituents include: sulfate (SO4);
nitrate (NO3); ammonium; elemental carbon; a great variety
of organic compounds; and inorganic material (including metals, dust,
sea salt, and other trace elements) generally referred to as
``crustal'' material, although it may contain material from other
sources. Airborne particles generally less than or equal to 2.5
micrometers in diameter are considered to be ``fine particles'' (also
referred to as PM2.5). (A micrometer is one-millionth of a
meter, and 2.5 micrometers is less than one-seventh the average width
of a human hair.) ``Primary'' particles are emitted directly into the
air as a solid or liquid particle (e.g., elemental carbon from diesel
engines or fire activities, or condensable organic particles from
gasoline engines). ``Secondary'' particles (e.g., sulfate and nitrate)
form in the atmosphere as a result of various chemical reactions.
(Section II of the proposed rule included detailed technical discussion
on PM2.5, its precursors, formation processes, and emissions
sources.)
The EPA established air quality standards for PM2.5
based on evidence from numerous health studies demonstrating that
serious health effects are associated with exposures to elevated levels
of PM2.5. Epidemiological studies have shown statistically
significant correlations between elevated PM2.5 levels and
premature mortality. Other important
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effects associated with PM2.5 exposure include aggravation
of respiratory and cardiovascular disease (as indicated by increased
hospital admissions, emergency room visits, absences from school or
work, and restricted activity days), changes in lung function and
increased respiratory symptoms, as well as new evidence for more subtle
indicators of cardiovascular health. Individuals particularly sensitive
to PM2.5 exposure include older adults, people with heart
and lung disease, and children.
On July 18, 1997, we revised the NAAQS for particulate matter (PM)
to add new standards for fine particles, using PM2.5 as the
indicator. We established health-based (primary) annual and 24-hour
standards for PM2.5 (62 FR 38652).\1\ The annual standard
was set at a level of 15 micrograms per cubic meter, as determined by
the 3-year average of annual mean PM2.5 concentrations. The
24-hour standard was set at a level of 65 micrograms per cubic meter,
as determined by the 3-year average of the 98th percentile of 24-hour
concentrations.
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\1\ The original annual and daily standards for particles
generally less than or equal to 10 micrometers in diameter (also
referred to as PM10) were established in 1987. In the
1997 PM NAAQS revision, EPA also revised the standards for
PM10, but these revised PM10 standards were
later vacated by the court, and the 1987 PM10 standards
remained in effect. In the 2006 NAAQS revision, the 24-hour
PM10 standard was retained but the annual standard was
revoked. Today's implementation rule and guidance does not address PM10.
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Attainment of the 1997 PM2.5 standards is estimated to
lead to reductions in health impacts, including tens of thousands fewer
premature deaths each year, thousands fewer hospital admissions and
emergency room visits each year, hundreds of thousands fewer absences
from work and school, and hundreds of thousands fewer respiratory
illnesses in children annually. The EPA's evaluation of the science
concluded that there was not sufficient information to either support or
refute the existence of a threshold for health effects from PM exposure.\2\
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\2\ Environmental Protection Agency. (2004a). Air Quality
Criteria for Particulate Matter. Research Triangle Park, NC:
National Center for Environmental Assessment--RTP, Office of
Research and Development, U.S. Environmental Protection Agency,
Research Triangle Park, NC 27711; report no. EPA/600/P-99/002aF and
EPA/600/P-99/002bF. October 2004.
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We subsequently completed in October 2006 another review of the
NAAQS for PM. With regard to the primary standards, the 24-hour
PM2.5 standard was strengthened to a level of 35 micrograms
per cubic meter, based on the 3-year average of the 98th percentile of
24-hour concentrations, and the level of the annual standard remained
unchanged.\3\ Attainment of the 2006 PM2.5 standards is
estimated to lead to additional reductions in health impacts, including
approximately 1,200 to 13,000 fewer premature deaths each year, 1,630
fewer hospital admissions and 1,200 fewer emergency room visits for
asthma each year, 350,000 fewer absences from work and school, and
155,300 fewer respiratory illnesses in children annually.\4\
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\3\ The revised fine particle NAAQS were published on October
17, 2006 (71 FR 61144). See EPA's Web site for additional
information: http://www.epa.gov/pm/index.html.
\4\ Regulatory Impact Analysis for Particulate Matter National
Ambient Air Quality Standards (September 2006), page ES-8. The
mortality range includes estimates based on the results of an expert
elicitation study, along with published epidemiological studies.
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In both 1997 and 2006 EPA established welfare-based (secondary)
standards identical to the levels of the primary standards. The
secondary standards are designed to protect against major environmental
effects of PM2.5 such as visibility impairment, soiling, and
materials damage. The EPA also established the regional haze
regulations in 1999 for the improvement of visual air quality in
national parks and wilderness areas across the country. Because
regional haze is caused primarily by light scattering and light
absorption by fine particles in the atmosphere, EPA is encouraging the
States to integrate their efforts to attain the PM2.5
standards with those efforts to establish reasonable progress goals and
associated emission reduction strategies for the purposes of improving
air quality in our treasured natural areas under the regional haze program.
The scientific assessments used in the development of the
PM2.5 standards included a scientific peer review and public
comment process. We developed scientific background documents based on
the review of hundreds of peer-reviewed scientific studies. The Clean
Air Scientific Advisory Committee, a congressionally mandated group of
independent scientific and technical experts, provided extensive review
of these assessments, and found that EPA's review of the science
provided an adequate basis for the EPA Administrator to make a
decision. More detailed information on health effects of
PM2.5 can be found on EPA's Web site at: http://www.epa.gov/
air/urbanair/pm/index.html. Additional information on EPA's scientific
assessment documents supporting the 1997 standards are available at
http://www.epa.gov/ttn/oarpg/t1cd.html; additional scientific assessment
information on the 2006 standards is available at:
http://www.epa.gov/ttn/naaqs/standards/pm/s_pm_cr_cd.html.
The EPA issued final PM2.5 designations for areas
violating the 1997 standards on December 17, 2004. They were published
in the Federal Register on January 5, 2005 (70 FR 944). On April 5,
2005, EPA issued a supplemental notice which changed the designation
status of eight areas from nonattainment to attainment based on newly
updated 2002-2004 air quality data (70 FR 19844; published in the
Federal Register on April 14, 2005). A total of 39 areas were
designated as nonattainment for the 1997 PM2.5 standards.
The population of these areas is estimated at about 90 million (or more
than 30% of the U.S. population). Most of these areas only violate the
annual standard, but a few violate both the annual and 24-hour standards.
The nonattainment designation for an area starts the process
whereby a State or Tribe must develop an implementation plan that
includes, among other things, a demonstration showing how it will
attain the ambient standards by the attainment dates required in the
CAA. Under section 172(b), States have up to 3 years after EPA's final
designations to submit their SIPs to EPA. These SIPs will be due on
April 5, 2008, 3 years from the effective date of the designations.
Section 172(a)(2) of the Act requires States to attain the
standards as expeditiously as practicable but within 5 years of
designation (i.e. attainment date of April 2010 based on air quality
data for 2007-2009), or within up to 10 years of designation (i.e. to
April 2015) if the EPA Administrator extends an area's attainment date
by 1-5 years based upon the severity of the nonattainment problem or
the feasibility of implementing control measures.
Virtually all nonattainment problems appear to result from a
combination of local emissions and transported emissions from upwind
areas. The structure of the CAA requires EPA to develop national rules
for certain types of sources which are also significant contributors to
local air quality problems, including motor vehicles and fuels. It also
provides for States to address emissions sources on an area-specific
basis through such requirements as RACT, RACM, and RFP.
We believe that to attain the PM2.5 standards, it is
important to pursue emissions reductions simultaneously on the local,
regional, and national levels. The EPA issued the Clean Air Interstate
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Rule (CAIR) \5\ on March 10, 2005 to address the interstate transport
of sulfur dioxide and nitrogen oxide emissions primarily from power
plants. Section 110 gives EPA the authority to require SIPs to
``prohibit * * * any source or other type of emission activity within
the State from emitting any air pollutant in amounts which will
contribute significantly to nonattainment in, or interfere with
maintenance by, any other State with respect to'' any NAAQS, and to
prohibit sources or emission activities from emitting pollutants in
amounts which will interfere with measures required to be included in
State plans to prevent significant deterioration of air quality or to
protect visibility (such as the protection of 156 mandatory Federal
class I areas under the regional haze rule \6\). CAIR employs the same
emissions trading approach used to achieve cost-effective emission
reductions under the acid rain program. It outlines a two-phase program
with increasingly tighter power plant emissions caps for 28 eastern
states and the District of Columbia: SO2 caps of 3.6 million
tons in 2010, and 2.5 million in 2015; NOX caps of 1.5 in
2009 and 1.3 in 2015; and NOX ozone season caps of 580,000
tons in 2009 and 480,000 tons in 2015. Emission caps are divided into
State SO2 and NOX budgets. By the year 2015, the
Clean Air Interstate Rule is estimated to result in:
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\5\ See http://www.epa.gov/cair.
\6\ See 64 FR 35714, July 1, 1999.
--$85 to $100 billion in annual health benefits, including preventing
17,000 premature deaths, millions of lost work and school days, and
tens of thousands of non-fatal heart attacks and hospital admissions
annually.
--Nearly $2 billion in annual visibility benefits in southeastern
national parks, such as Great Smoky and Shenandoah.
--Significant regional reductions in sulfur and nitrogen deposition,
reducing the number of acidic lakes and streams in the eastern U.S.
Over the past several years, EPA has also issued a number of
regulations addressing emissions standards for new cars, trucks and
buses. These standards are providing reductions in motor vehicle
emissions of volatile organic compounds (VOCs, also referred to as
hydrocarbons), NOX, and direct PM emissions (such as
elemental carbon) as older vehicles are retired and replaced. Other
existing rules are designed to reduce emissions from several categories
of nonroad engines. The Tier 2 motor vehicle emission standards,
together with the associated requirements to reduce sulfur in gasoline,
are estimated to provide additional benefits nationally beginning in
2004.\7\ When the new tailpipe and sulfur standards are fully
implemented, Americans are estimated to benefit from the clean-air
equivalent of removing 164 million cars from the road. These new
standards require passenger vehicles to have emissions 77 to 95 percent
cleaner than those on the road today and require fuel manufacturers to
reduce the sulfur content of gasoline by up to 90 percent. In addition,
the 2001 heavy-duty diesel engine regulations \8\ will lead to
continued emissions reductions as older vehicles in that engine class
are retired and fleets turn over. New emission standards began to take
effect for model year 2007 and apply to heavy-duty highway engines and
vehicles. These standards are based on the use of high-efficiency
catalytic exhaust emission control devices or comparably effective
advanced technologies. Because these devices are damaged by sulfur, the
level of sulfur in highway diesel fuel was to be reduced by 97 percent
by mid-2006. We project a 2.6 million ton reduction of NOX
emissions in 2030 when the current heavy-duty vehicle fleet is
completely replaced with newer heavy-duty vehicles that comply with
these emission standards. By 2030, we estimate that this program will
reduce annual emissions of hydrocarbons by 115,000 tons and PM by
109,000 tons. These emissions reductions are on par with those that we
anticipate from new passenger vehicles and low sulfur gasoline under
the Tier 2 program.
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\7\ See Tier II emission standards at 65 FR 6698, February 10, 2000.
\8\ See heavy-duty diesel engine regulations at 66 FR 5002,
January 18, 2001.
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The EPA also finalized national rules in May 2004 to reduce
significantly PM2.5 and NOX emissions from
nonroad diesel-powered equipment.\9\ These nonroad sources include
construction, agricultural, and industrial equipment, and their
emissions constitute an important fraction of the inventory for direct
PM2.5 emissions (such as elemental carbon and organic
carbon), and NOX. The EPA estimates that affected nonroad
diesel engines currently account for about 44 percent of total diesel
PM emissions and about 12 percent of total NOX emissions
from mobile sources nationwide. These proportions are even higher in
some urban areas. The diesel emission standards will reduce emissions
from this category by more than 90 percent, and are similar to the
onroad engine requirements implemented for highway trucks and buses.
Because the emission control devices can be damaged by sulfur, EPA also
established requirements to reduce the allowable level of sulfur in
nonroad diesel fuel by more than 99 percent by 2010. In 2030, when the
full inventory of older nonroad engines has been replaced, the nonroad
diesel program will annually prevent up to 12,000 premature deaths, one
million lost work days, 15,000 heart attacks and 6,000 children's
asthma-related emergency room visits.
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\9\ For more information on the proposed nonroad diesel engine
standards, see EPA's Web site: http://www.epa.gov/nonroad/.
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The EPA expects the implementation of regional and national
emission reduction programs such as CAIR and the suite of mobile source
rules described above to provide significant air quality improvements
for PM2.5 nonattainment areas. At the same time, analyses
for the final CAIR rule indicate that without implementation of local
measures, a number of PM2.5 areas are projected to remain in
nonattainment status in the 2010-2015 timeframe. Thus, EPA believes
that local and State emission reduction efforts will need to play an
important role in addressing the PM2.5 problem as well. The
EPA will work closely with States, Tribes, and local governments to
develop appropriate in-state pollution reduction measures to complement
regional and national strategies to meet the standards expeditiously
and in a cost-effective manner. States will need to evaluate
technically and economically feasible emission reduction opportunities
and determine which measures can be reasonably implemented in the near
term. Local and regional emission reduction efforts should proceed
concurrently and expeditiously.
The promulgation of a revised 24-hour PM2.5 standard
effective on December 18, 2006 has initiated another process of State
recommendations, and the eventual designation by EPA of areas not
attaining the revised standard. The additional designations are to be
completed within two years from the effective date, although EPA may
take an additional year to complete the designations if it determines
it does not have sufficient information. State plans to attain the 24-
hour standard would then be due within three years of the final
designations. A number of areas, including some that are already
designated as not attaining the 1997 standards, may be exceeding the
revised 24-hour standard. The EPA encourages State and local
governments to be mindful of the strengthened 24-hour standard as they
adopt emission reduction strategies to attain the 1997 standards. Such
steps may help with
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future attainment efforts, or even help some areas avoid a
nonattainment designation for the 24-hour standard in the first place.
The public health benefits of meeting the PM2.5
standards are estimated to be significant. Even small reductions in
PM2.5 levels may have substantial health benefits on a
population level. For example, in a moderate-sized metropolitan area
with a design value of 15.5 [mu]g/m3, efforts to improve annual average
air quality down to the level of the standard (15.0 [mu]g/m3) are
estimated to result in as many as 25-50 fewer mortalities per year due
to air pollution exposure. In a smaller city, the same air quality
improvement from 15.5 to 15.0 [mu]g/m3 still are estimated to result in
a number of avoided mortalities per year. These estimates are based on
EPA's standard methodology for calculating health benefits as used in
recent rulemakings.\10\ In addition, because many different precursors
contribute to the formation of fine particles, reductions in pollutants
that contribute to PM2.5 also can provide concurrent
benefits in addressing a number of other air quality problems--such as
ground-level ozone, regional haze, toxic air pollutants, and urban
visibility impairment.
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\10\ See: U.S. EPA 2006. Regulatory Impact Analysis for the
Particulate Matter National Ambient Air Quality Standards. Air
Benefits and Cost Group, Office of Air Quality Planning and
Standards, Research Triangle Park, N.C. October 6, 2006. Appendix A
provides an analysis of estimated benefits and costs of attaining
the 1997 PM NAAQS standards in 2015.
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In order to assist States in developing effective plans to address
the local component of the PM2.5 nonattainment problem, EPA
is issuing this final fine particle implementation rule. The EPA is
issuing this rule to implement the 1997 PM2.5 NAAQS in
accordance with the statutory requirements of the CAA set forth in
Subpart 1 of Part D of Title 1, i.e., sections 171-179B of the Act. The
EPA believes that the CAA directs the Agency to implement new or
revised NAAQS in nonattainment areas solely in accordance with Subpart
1, unless another Subpart of the Act also applies to the particular
NAAQS at issue. In this case, EPA has concluded that Congress did not
intend the Agency to implement particulate matter NAAQS other than
those using PM10 as the indicator in accordance with Subpart
4 of Part D of Title 1, i.e., sections 188-190 of the CAA. Moreover,
EPA believes that implementation of the PM2.5 NAAQS under
the provisions of Subpart 1 is more appropriate, given the inherent
nature of the PM2.5 nonattainment problem. In contrast to
PM10, EPA anticipates that achieving the NAAQS for
PM2.5 will generally require States to evaluate different
sources for controls, to consider controls of one or more precursors in
addition to direct PM emissions, and to adopt different control
strategies. As a result, EPA has concluded that the provisions of
Subpart 1 will allow States and EPA to tailor attainment plans so that
they can be based more specifically upon the facts and circumstances of
each nonattainment area.
The proposed clean air fine particle implementation rule was issued
on November 1, 2005 (70 FR 65984). About 100 comments were received
from private citizens and parties representing industry, state and
local governments, environmental groups, and federal agencies. Section
II of this document describes the primary elements of the fine particle
implementation program. Each section summarizes the relevant policies
and options discussed in the proposed rule, discusses the final policy
set forth by EPA in the final rule, and provides responses to the major
comments received on each issue.
II. Elements of the Clean Air Fine Particle Implementation Rule
A. Precursors and Pollutants Contributing to Fine Particle Formation
1. Introduction
The main precursor gases associated with fine particle formation
are SO2, NOX, volatile organic compounds (VOC),
and ammonia. This section provides technical background on each
precursor, discusses the policy approach for addressing each precursor
under the PM2.5 implementation program, and responds to key
issues raised in the public comment process. A subsection is also
included on direct PM2.5 emissions to address key comments
received on this issue as well.
Gas-phase precursors SO2, NOX, VOC, and
ammonia undergo chemical reactions in the atmosphere to form secondary
particulate matter. Formation of secondary PM depends on numerous
factors including the concentrations of precursors; the concentrations
of other gaseous reactive species; atmospheric conditions including
solar radiation, temperature, and relative humidity (RH); and the
interactions of precursors with preexisting particles and with cloud or
fog droplets. Several atmospheric aerosol species, such as ammonium
nitrate and certain organic compounds, are semivolatile and are found
in both gas and particle phases. Given the complexity of PM formation
processes, new information from the scientific community continues to
emerge to improve our understanding of the relationship between sources
of PM precursors and secondary particle formation.
As an initial matter, it is helpful to clarify the terminology we
use throughout this notice to discuss precursors. We recognize
NOX, SO2, VOCs, and ammonia as precursors of
PM2.5 in the scientific sense because these pollutants can
contribute to the formation of PM2.5 in the ambient air. In
section II.K on emission inventory issues, we make the point that
because of the complex and variable interaction of multiple pollutants
and precursors in the formation of fine particles, it is important for
States and EPA to continue to characterize and improve the emissions
inventories for all PM2.5 precursors. The States and EPA
need to use the best available information available in conducting air
quality modeling and other assessments. At the same time, the
refinement of emissions inventories, the overall contribution of
different fine particle precursors to PM2.5 formation, and
the efficacy of alternative potential control measures will vary by
location. This requires that we further consider in this action how
States should address these PM2.5 precursors in their
PM2.5 attainment plan programs. Thus, we require emission
inventories to include the best available information on all pollutants
and precursors that contribute to PM2.5 concentrations, and
at same time we use the term ``PM2.5 attainment plan
precursor'' to describe only those precursors that are required to be
evaluated for control strategies in a specific PM2.5
nonattainment area or maintenance area plan.
In this rule, EPA has not made a finding that all precursors should
be evaluated for possible controls in each specific nonattainment area.
The policy approach in the rule instead requires sulfur dioxide to be
evaluated for control measures in all areas, and describes general
presumptive policies for NOX, ammonia, and VOC for all
nonattainment areas. The rule provides a mechanism by which the State
and/or EPA can make an area-specific demonstration to reverse the
general presumption for these three precursors. States must also
consider any relevant information brought forward by interested parties
in the SIP planning and development process. (See section II.A.8 for
additional discussion on these issues.)
In the following sections, we discuss how States must evaluate
PM2.5 precursors for nonattainment program issues in
PM2.5 implementation plans,
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including issues such as RACT, RACM, and reasonable further progress.
This discussion in the final rule is linked to precursor policies for
the implementation of the new source review program, the transportation
conformity program, the general conformity program, and the regional
haze program. All of these programs take effect prior to approval of
SIPs for attaining the PM2.5 NAAQS. In the case of NSR, the
program applies on the effective date of the nonattainment area
designation. In the case of transportation conformity and general
conformity, the program takes effect 1 year from the effective date of
designation of the nonattainment area (i.e., April 5, 2006 for areas
designated nonattainment effective April 5, 2005). Thus, for each of
these programs there is an interim period between the date the program
becomes applicable to a given nonattainment area and the date the State
receives EPA approval of its overall PM2.5 implementation plan.
2. Legal Authority to Regulate Precursors
a. Background
The CAA authorizes the Agency to regulate criteria pollutant
precursors. The term ``air pollutant'' is defined in section 302(g) to
include ``any precursors to the formation of any air pollutant, to the
extent the Administrator has identified such precursor or precursors
for the particular purpose for which the term `air pollutant' is
used.'' The first clause of this second sentence in section 302(g)
explicitly authorizes the Administrator to identify and regulate
precursors as air pollutants under other parts of the CAA. In addition,
the second clause of the sentence indicates that the Administrator has
discretion to identify which pollutants should be classified as
precursors for particular regulatory purposes. Thus, we do not
necessarily construe the CAA to require that EPA identify a particular
precursor as an air pollutant for all regulatory purposes where it can
be demonstrated that various CAA programs address different aspects of
the air pollutant problem. Likewise, we do not interpret the CAA to
require that EPA treat all precursors of a particular pollutant the
same under any one program when there is a basis to distinguish between
such precursors. For example, in a rule addressing PM2.5
precursors for purposes of the transportation conformity program, we
chose to adopt a different approach for one precursor based on the
limited emissions of that precursor from onroad mobile sources and the
degree to which it contributes to PM2.5 concentrations. (70
FR 24280; May 6, 2005).
Other provisions of the CAA reinforce our reading of section 302(g)
that Congress intended precursors to NAAQS pollutants to be subject to
the air quality planning and control requirements of the CAA, but also
recognized that there may be circumstances where it is not appropriate
to subject precursors to certain requirements of the CAA. Section 182
of the CAA provides for the regulation of NOX and VOCs as
precursors to ozone in ozone nonattainment areas, but also provides in
section 182(f) that major stationary sources of NOX (an
ozone precursor) are not subject to emission reductions controls for
ozone where the State shows through modeling that NOX
reductions do not decrease ozone. Section 189(e) provides for the
regulation of PM10 precursors in PM10
nonattainment areas, but also recognizes that there may be certain
circumstances (e.g. if precursor emission sources do not significantly
contribute to PM10 levels) where it is not appropriate to
apply control requirements to PM10 precursors. The
legislative history of Section 189(e) recognized the complexity behind
the science of precursor transformation into PM10 ambient
concentrations and the need to harmonize the regulation of
PM10 precursors with other provisions of the CAA:
The Committee notes that some of these precursors may well be
controlled under other provisions of the CAA. The Committee intends
that * * * the Administrator will develop models, mechanisms, and
other methodology to assess the significance of the PM10
precursors in improving air quality and reducing PM10.
Additionally, the Administrator should consider the impact on ozone
levels of PM10 precursor controls. The Committee expects
the Administrator to harmonize the PM10 reduction
objective of this section with other applicable regulations of this
CAA regarding PM10 precursors, such as NOX.
See H. Rpt. 101-490, Pt. 1, at 268 (May 17, 1990), reprinted in S.
Prt. 103-38, Vol. II, at 3292.
In summary, section 302(g) of the CAA clearly calls for the
regulation of precursor pollutants, but the CAA also identifies
circumstances when it may not be appropriate to regulate precursors and
gives the Administrator discretion to determine how to address
particular precursors under various programs required by the CAA. Due
to the complexities associated with precursor emissions and their
variability from location to location, we believe that in certain
situations it may not be effective or appropriate to control a certain
precursor under a particular regulatory program or for EPA to require
similar control of a particular precursor in all areas of the country.
b. Final Rule
The final rule maintains the same legal basis for regulating
precursors as was described in the proposal and in the background
section above. We also include a clarification of the term
``significant contributor.''
In the proposal, when considering the impacts of the precursors
NOX, VOC and ammonia on ambient concentrations of
particulate matter, we referred to the possibility of reversing the
presumed approach for regulating or not regulating a precursor if it
can be shown that the precursor in question is or is not a
``significant contributor'' to PM2.5 concentrations within
the specific nonattainment area. ``Significant contribution'' in this
context is a different concept than that in Section 110(a)(2)(D).
Section 110(a)(2)(D) prohibits States from emitting air pollutants in
amounts which significantly contribute to nonattainment or other air
quality problems in other states. Consistent with the discussion of
sections 189(e) and 302(g) above, we are clarifying that the use in
this implementation rule of the term ``significant contribution'' to
the nonattainment area's PM2.5 concentration means that a
significant change in emissions of the precursor from sources in the
state would be projected to provide a significant change in
PM2.5 concentrations in the nonattainment area. For example,
if modeling indicates that a reduction in a state's NOX
emissions would reduce ambient PM2.5 levels in the
nonattainment area, but that a reduction in ammonia emissions would
result in virtually no change in ambient PM2.5 levels, this
would suggest that NOX is a significant contributor but that
ammonia is not. The EPA in this rule is not establishing a quantitative
test for determining whether PM2.5 levels in a nonattainment
area change significantly in response to reductions in precursor
emissions in a state. However, in considering this question, it is
relevant to consider that relatively small reductions in PM2.5
levels are estimated to result in worthwhile public health benefits.
This approach to identifying a precursor for regulation reflects
atmospheric chemistry conditions in the area and the magnitude of
emissions of the precursor in the area or State. Assessments of which
source categories are more cost effective or technically feasible to
control should be part of the later RACT and RACM assessment, to
[[Page 20591]]
occur after the basic assessment of which precursors are to be
regulated is completed.
In the proposed regulatory text, the provisions for reversing
presumptions for NOX, VOC and ammonia included consideration
of whether the precursor would significantly contribute to ``other
downwind air quality concerns.'' In the final rule we have removed that
language to clarify that identification of attainment plan precursors
involves evaluation of the impact on PM2.5 levels in a
nonattainment area of precursor emissions from sources within the
state(s) where the nonattainment area is located. Other parts of the
Act, notably section 110(a)(2)(D) and section 126, focus on interstate
transport of pollutants.
c. Comments and Responses
Comment: The EPA received several comments supporting EPA's
interpretation of 302(g) to determine the appropriate regulatory status
of each precursor pollutant.
Response: The EPA agrees with the commenters. In establishing
section 302(g), Congress intended that precursors to NAAQS pollutants
be subject to the air quality planning and control requirements of the
CAA. However, the CAA also recognizes that there may be circumstances
where it is not appropriate to subject precursors to certain
requirements of the CAA.
Comment: The EPA received several comments regarding the
applicability of section 189(e), noting that it requires states to
presumptively control sources of PM10 precursors except
where the EPA ``determines that such sources [of precursors] do not
significantly contribute to PM10 levels which exceed the
standard in the area.'' Several commenters stated that EPA does not
have the legal authority to regulate PM2.5 precursors in a
different manner. Several commenters maintained that all
PM2.5 precursors presumptively should be subject to
regulation unless demonstrated by the State as not a significant
contributor to PM2.5 concentrations in a specific area.
Response: As stated above, EPA believes that section 302(g) allows
the Administrator to presumptively not require certain precursors to be
addressed in PM2.5 implementation plans generally, while
allowing the State or EPA to make a finding for a specific area to
override the general presumption. In the following pollutant-specific
sections of this preamble, EPA finds that at this time there is
sufficient uncertainty regarding whether certain precursors
significantly contribute to PM2.5 concentrations in all
nonattainment areas such that the policy set forth in this rule does
not presumptively require certain precursors (ammonia, VOC) to be
controlled in each area. However, the State or EPA may reverse the
presumption and regulate a precursor if it provides a demonstration
showing that the precursor is a significant contributor to
PM2.5 concentrations in the area. In addition, if in the
State's SIP planning and adoption process a commenter provides
additional information suggesting an alternative policy for regulating
a particular precursor, the State will need to respond to this
information in its rulemaking action.
3. Policy for Ammonia
[Section II.E.2 of November 1, 2005 proposed rule (70 FR 65999);
sec. 51.1002 in draft and final regulatory text.]
a. Background
Ammonia (NH3) is a gaseous pollutant that is emitted by
natural and anthropogenic sources. Emissions inventories for ammonia
are considered to be among the most uncertain of any species related to
PM. Ammonia serves an important role in neutralizing acids in clouds,
precipitation and particles. In particular, ammonia neutralizes
sulfuric acid and nitric acid, the two key contributors to acid
deposition (acid rain). Deposited ammonia also can contribute to
problems of eutrophication in water bodies, and deposition of ammonium
particles may effectively result in acidification of soil as ammonia is
taken up by plants. The NARSTO Fine Particle Assessment \11\ indicates
that reducing ammonia emissions where sulfate concentrations are high
may reduce PM2.5 mass concentrations, but may also increase
the acidity of particles and precipitation. An increase in particle
acidity is suspected to be linked with human health effects and with an
increase in the formation of secondary organic compounds. Based on the
above information and further insights gained from the NARSTO Fine
Particle Assessment, it is apparent that the formation of particles
related to ammonia emissions is a complex, nonlinear process.
---------------------------------------------------------------------------
\11\ NARSTO (2004) (Particulate Matter Assessment for Policy
Makers: A NARSTO Assessment. P. McMurry, M. Shepherd, and J. Vickery, eds.
Cambridge University Press, Cambridge, England. ISBN 0 52 184287 5.
---------------------------------------------------------------------------
Though recent studies have improved our understanding of the role
of ammonia in aerosol formation, ongoing research is required to better
describe the relationships between ammonia emissions, particulate
matter concentrations, and related impacts. The control techniques for
ammonia and the analytical tools to quantify the impacts of reducing
ammonia emissions on atmospheric aerosol formation are both evolving.
Also, area-specific data are needed to evaluate the effectiveness of
reducing ammonia emissions on reducing PM2.5 concentrations
in different areas, and to determine where ammonia decreases may
increase the acidity of particles and precipitation.
The proposal showed consideration for the uncertainties about
ammonia emissions inventories and about the potential efficacy of
ammonia control measures by providing for a case-by-case approach. It
was recommended that each State should evaluate whether reducing
ammonia emissions would lead to PM2.5 reductions in their
specific PM2.5 nonattainment areas. The proposed policy did
not require States to address ammonia as a PM2.5 attainment
plan precursor, unless a technical demonstration by the State or EPA
showed that ammonia emissions from sources in the State significantly
contribute to PM2.5 concentrations in a given nonattainment
area or to other downwind air quality concerns. Where the State or EPA
has determined that ammonia is a significant contributor to
PM2.5 formation in a nonattainment area, the State would be
required to evaluate control measures for ammonia emissions in its
nonattainment SIP due in 2008, in the implementation of the PM program,
and in other associated programs in that area.
b. Final Rule
In the final rule, ammonia is presumed not to be a PM2.5
attainment plan precursor, meaning that the State is not required to
address ammonia in its attainment plan or evaluate sources of ammonia
emissions for reduction measures. This presumption can be reversed
based on an acceptable technical demonstration for a particular area by
the State or EPA. If a technical demonstration by the State or EPA
shows that ammonia emissions from sources in the State significantly
contribute to PM2.5 concentrations in a given nonattainment
area, the State must then evaluate and consider control strategies for
reducing ammonia emissions in its nonattainment SIP due in 2008, in the
implementation of the PM2.5 program. Technical
demonstrations on ammonia should also consider the potential for
atmospheric and particle acidity to increase with ammonia reductions.
Further discussion about technical demonstrations to
[[Page 20592]]
support reversing a PM2.5 precursor presumption is included
in section II.A.8 below.
This approach was retained from the proposal because of continued
uncertainties regarding ammonia emission inventories and the effects of
ammonia emission reductions. Ammonia emission inventories are presently
very uncertain in most areas, complicating the task of assessing
potential impacts of ammonia emissions reductions. In addition, data
necessary to understand the atmospheric composition and balance of
ammonia and nitric acid in an area are not widely available across
PM2.5 nonattainment areas, making it difficult to predict
the results of potential ammonia emission reductions. Ammonia
reductions may be effective and appropriate for reducing
PM2.5 concentrations in selected locations, but in other
locations such reductions may lead to minimal reductions in
PM2.5 concentrations and increased atmospheric acidity.
Research projects continue to expand our collective understanding of
these issues, but at this time EPA believes this case-by-case policy
approach is appropriate. In light of these uncertainties, we encourage
States to continue efforts to better understand the role of ammonia in
its fine particle problem areas.
c. Comments and Responses
Comment: One commenter stated that scientific understanding of the
complexities of PM formation from ammonia is limited. The commenter
claimed that the reduction of ammonia will not reduce PM in many areas,
and speciated PM data to investigate the potential decrease in PM from
ammonia emissions reductions is not available in all areas.
Response: The final rule takes these uncertainties into
consideration by allowing ammonia to be addressed on a case-by-case
basis. For any area about which enough information is available to
determine that ammonia emission reductions would lead to a beneficial
reduction in PM2.5, the State can develop a technical
demonstration justifying the control of ammonia. If the State chooses
to develop such a demonstration, preferably it should be completed as
part of the SIP development process and prior to the adoption of control
measures, in consultation with the appropriate EPA regional office.
Comment: Some commenters claimed that requiring no action on some
precursors is counter to the requirement in sections 172(a)(2) and 188
to attain the NAAQS as expeditiously as practicable. They also asserted
that presuming that ammonia is not a PM2.5 attainment plan
precursor violates 302(g) by improperly delegating authority to the States.
Response: In many areas, reducing ammonia emissions could have
little effect on PM2.5 concentrations and could lead to the
potentially harmful effect of increased atmospheric acidity. While
States are not required to take action on ammonia sources under this
policy, States would be required to address information on ammonia
brought to their attention during the planning and rule adoption
process. Under this approach, States should assess whether ammonia
reductions would lead to reduced PM2.5 concentrations in
specific nonattainment areas. If the State decides that ammonia
reductions could yield beneficial reductions in PM2.5, the
State should complete a technical demonstration supporting a reversal
of the presumption. The EPA does not believe that this approach
improperly delegates authority to the States. It establishes a general
presumption for all areas through this rulemaking process, and allows
for the presumption to be modified by the State or EPA on a case-by-
case basis. EPA still retains the ability to make a technical
demonstration for any area if appropriate to reverse the presumption
and require ammonia to be addressed in its attainment plan.
Comment: Some commenters stated that the results of a large study
on air emissions from concentrated animal feeding operations (CAFOs)
should be evaluated before requiring control of ammonia in areas where
agriculture is alleged to be a major source.
Response: The $15 million national CAFO consent agreement study
coordinated by Purdue University will greatly improve ammonia and VOC
emissions inventories and our understanding of the impacts of
agricultural emissions on particle formation. The EPA recognizes that
the agricultural emissions study is expected to provide data for future
planning purposes, and we expect that some of the results of the study
will not be available in time to be considered in the development of
PM2.5 State Implementation Plans dues in April 2008.
However, if a State believes it has sufficient technical information to
warrant regulation of ammonia emissions in their 2008 implementation
plans, it may include in its plan a demonstration to reverse the
presumption as well as emission reduction measures. The EPA will review
each submittal on a case-by-case basis.
Comment: A presumption to not address ammonia will impede certain
states (i.e. those that have provisions requiring their regulations to
be ``no stricter than Federal'' provisions) from regulating ammonia.
Response: This presumptive approach to ammonia will not restrict
States from addressing ammonia in their PM2.5 attainment
plans. If a State has information indicating that reductions in ammonia
emissions would cause beneficial reductions in PM2.5
concentrations, the State can make a technical demonstration to reverse
the presumption. In such cases, inclusion of ammonia as a
PM2.5 attainment plan precursor would not be considered
stricter than Federal requirements. Under the policy in the final rule,
the Federal government or the State may assess the impact of ammonia in
a particular area and determine whether the presumption of
insignificance is appropriate or whether ammonia is in fact a
significant contributor to the PM2.5 problem in the area.
4. Policy for VOC
[Section II.E.2 of November 1, 2005 proposed rule (70 FR 65999);
sec. 51.1002 in draft and final regulatory text.]
a. Background
The VOC policy in this rule addresses volatile and semivolatile
organic compounds, generally up to 24 carbon atoms. High molecular
weight organic compounds (typically 25 carbon atoms or more) are
emitted directly as primary organic particles and exist primarily in
the condensed phase at ambient temperatures. Accordingly, high
molecular weight organic compounds are to be regulated as primary
PM2.5 emissions for the purposes of the PM2.5
implementation program.
The organic component of ambient particles is a complex mixture of
hundreds or even thousands of organic compounds. These organic
compounds are either emitted directly from sources (i.e. primary
organic aerosol) or can be formed by reactions in the ambient air (i.e.
secondary organic aerosol, or SOA). Volatile organic compounds are key
precursors in the formation processes for both SOA and ozone. The
relative importance of organic compounds in the formation of secondary
organic particles varies from area to area, depending upon local
emissions sources, atmospheric chemistry, and season of the year.
The lightest organic molecules (i.e., molecules with six or fewer
carbon atoms) occur in the atmosphere mainly as vapors and typically do
not directly
[[Page 20593]]
form organic particles at ambient temperatures due to the high vapor
pressure of their products. However, they participate in atmospheric
chemistry processes resulting in the formation of ozone and certain
free radical compounds (such as the hydroxyl radical [OH]) which in
turn participate in oxidation reactions to form secondary organic
aerosols, sulfates, and nitrates. These VOCs include all alkanes with
up to six carbon atoms (from methane to hexane isomers), all alkenes
with up to six carbon atoms (from ethene to hexene isomers), benzene
and many low-molecular weight carbonyls, chlorinated compounds, and
oxygenated solvents.
Intermediate weight organic molecules (i.e., compounds with 7 to 24
carbon atoms) often exhibit a range of volatilities and can exist in
both the gas and aerosol phase at ambient conditions. For this reason
they are also referred to as semivolatile compounds. Semivolatile
compounds react in the atmosphere to form secondary organic aerosols.
These chemical reactions are accelerated in warmer temperatures, and
studies show that SOA typically comprises a higher percentage of
carbonaceous PM in the summer as opposed to the winter. The production
of SOA from the atmospheric oxidation of a specific VOC depends on four
factors: Its atmospheric abundance, its chemical reactivity, the
availability of oxidants (O3, OH, HNO3), and the
volatility of its products. In addition, recent work suggests that the
presence of acidic aerosols may lead to an increased rate of SOA
formation. Aromatic compounds such as toluene, xylene, and trimethyl
benzene are considered to be the most significant anthropogenic SOA
precursors and have been estimated to be responsible for 50 to 70
percent of total SOA in some airsheds. Man-made sources of aromatics
gases include mobile sources, petrochemical manufacturing and solvents.
Some of the biogenic hydrocarbons emitted by trees are also considered
to be important precursors of secondary organic particulate matter.
Terpenes (and b-pinene, limonene, carene, etc.) and the sesquiterpenes
are expected to be major contributors to SOA in areas with significant
vegetation cover, but isoprene is not. Terpenes are very prevalent in
areas with pine forests, especially in the southeastern U.S. The rest
of the anthropogenic hydrocarbons (higher alkanes, paraffins, etc.)
have been estimated to contribute 5-20 percent to the SOA concentration
depending on the area.
The contribution of the primary and secondary components of organic
aerosol to the measured organic aerosol concentrations remains a
complex issue. Most of the research performed to date has been done in
southern California, and more recently in central California, while
fewer studies have been completed on other parts of North America. Many
studies suggest that the primary and secondary contributions to total
organic aerosol concentrations are highly variable, even on short time
scales. Studies of pollution episodes indicate that the contribution of
SOA to the organic particulate matter can vary from 20 percent to 80
percent during the same day.
Despite significant advances in understanding the origins and
properties of SOA, it remains probably the least understood component
of PM2.5. The reactions forming secondary organics are
complex, and the number of intermediate and final compounds formed is
voluminous. Some of the best efforts to unravel the chemical
composition of ambient organic aerosol matter have been able to
quantify the concentrations of hundreds of organic compounds
representing only 10-20 percent of the total organic aerosol mass. For
this reason, SOA continues to be a significant topic of research and
investigation.
Current scientific and technical information clearly shows that
carbonaceous material is a significant fraction of total
PM2.5 mass in most areas, that certain VOC emissions are
precursors to the formation of secondary organic aerosol, and that a
considerable fraction of the total carbonaceous material is likely from
local as opposed to regional sources. However, while significant
progress has been made in understanding the role of gaseous organic
material in the formation of organic PM, this relationship remains
complex. We recognize that further research and technical tools are
needed to better characterize emissions inventories for specific VOC
compounds, and to determine the extent of the contribution of specific
VOC compounds to organic PM mass.
In light of these factors, the proposed rule did not require States
to address VOCs as PM2.5 attainment plan precursors and
evaluate them for control measures, unless the State or EPA makes a
finding that VOCs significantly contribute to a PM2.5
nonattainment problem in the State or to other downwind air quality
concerns. Many PM2.5 nonattainment areas are also
nonattainment areas for the 8-hour ozone standard; control measures for
VOCs will be implemented in some of these areas, potentially providing
a co-benefit for PM2.5 concentrations.
b. Final Rule
The final rule maintains the same policy as proposed.\12\ States
are not required to address VOC in PM2.5 implementation
plans and evaluate control measures for such pollutants unless the
State or EPA makes a technical demonstration that emissions of VOCs
from sources in the State significantly contribute to PM2.5
concentrations in a given nonattainment area. Technical demonstrations
are discussed in section II.A.8 below. If a State chooses to make a
technical demonstration, it should be developed in advance of the
attainment demonstration.
---------------------------------------------------------------------------
\12\ The policy is the same as proposed, with the clarification
regarding downwind areas discussed above (Section A.2.b).
---------------------------------------------------------------------------
c. Comments and Responses
Comment: One commenter stated that our understanding of the
complexities of PM2.5 formation from VOCs is limited, that
speciated PM data are not available in all areas, and that VOC
reductions will not reduce PM2.5 in many areas.
Response: The EPA acknowledges the uncertainties regarding the role
of VOC in secondary organic aerosol formation. For this reason the
final rule does not presumptively include VOC as a regulated pollutant
for PM planning. However, if available data demonstrates that control
of VOC would reduce PM2.5 concentrations in an area, the
State or EPA may include VOC as an attainment plan precursor.
Comment: One commenter stated that the rationale that VOC should
not be considered a PM2.5 attainment plan precursor because
most PM areas are also ozone areas is not appropriate because many ozone
areas will attain soon and VOC reductions will still be needed for PM.
Response: The primary rationale for not including VOC as a
PM2.5 attainment plan precursor in every nonattainment area
is the uncertainty regarding the contribution of anthropogenic VOCs to
the formation of the organic carbon portion of fine particles. In
certain areas, EPA expects that VOC control measures will have some co-
benefits in the reduction of fine particulates. However, this reason
should not be considered the principal reason for the policy in the
final rule that VOCs presumptively should not be considered
PM2.5 attainment plan precursors. If a State or EPA
determines that VOCs do contribute significantly to PM2.5
concentrations in an area, the State will be required to evaluate
control measures for VOC as a PM2.5 attainment plan
[[Page 20594]]
precursor for that area. This approach will provide for regulation of
VOCs in locations where it is most appropriate.
Comment: One commenter suggested that EPA wait for the results of
the pending agricultural emissions study before requiring control of
VOCs in agricultural areas.
Response: The $15 million national CAFO consent agreement study
coordinated by Purdue University will greatly improve ammonia and VOC
emissions inventories and our understanding of the impacts of
agricultural emissions on particle formation. The EPA recognizes that
the agricultural emissions study is expected to provide data for future
planning purposes, and we expect that some of the results of the study
will not be available in time to be considered in the development of
PM2.5 State Implementation Plans dues in April 2008.
However, if a State believes it has sufficient technical information to
warrant regulation of VOC emissions in their 2008 implementation plans,
it may include in its plan a demonstration to reverse the presumption
as well as emission reduction measures. The EPA will review each
submittal on a case-by-case basis.
5. Policy for NOX
[Section II.E.2 of November 1, 2005 proposed rule (70 FR 65999);
sec. 51.1002 in draft and final regulatory text.]
a. Background
The sources of NOX are numerous and widespread. The
combustion of fossil fuel in boilers for commercial and industrial
power generation and in mobile source engines each account for
approximately 30 percent of NOX emissions in
PM2.5 nonattainment areas (based on 2001 emission inventory
information). Nitrates are formed from the oxidation of oxides of
nitrogen into nitric acid either during the daytime (reaction with OH)
or during the night (reactions with ozone and water). Nitric acid
continuously transfers between the gas and the condensed phases through
condensation and evaporation processes in the atmosphere. However,
unless it reacts with other species (such as ammonia, sea salt, or
dust) to form a neutralized salt, it will volatilize and not be
measured using standard PM2.5 measurement techniques. The
formation of aerosol ammonium nitrate is favored by the availability of
ammonia, low temperatures, and high relative humidity. Because ammonium
nitrate is semivolatile and not stable in higher temperatures, nitrate
levels are typically lower in the summer months and higher in the
winter months. The resulting ammonium nitrate is usually in the sub-
micrometer particle size range. Reactions with sea salt and dust lead
to the formation of nitrates in coarse particles. Nitric acid may be
dissolved in ambient aerosol particles.
Based on a review of speciated monitoring data analyses, it is
apparent that nitrate concentrations vary significantly across the
country. For example, in some southeastern locations, annual average
nitrate levels are in the range of 6 to 8 percent of total
PM2.5 mass, whereas nitrate comprises 40 percent or more of
PM2.5 mass in certain California locations. Nitrate
formation is favored by the availability of ammonia, low temperatures,
and high relative humidity. It is also dependent upon the relative
degree of nearby SO2 emissions because ammonia reacts
preferentially with SO2 over NOX. NOX
reductions are expected to reduce PM2.5 concentrations in
most areas. However, it has been suggested that in a limited number of
areas, NOX control would result in increased
PM2.5 mass by disrupting the ozone cycle and leading to
increased oxidation of SO2 to form sulfate particles, which
are heavier than nitrate particles. Because of the above factors, the
proposed rule presumed that States must evaluate and implement
reasonable controls on sources of NOX in all nonattainment
areas, but allowed for the State and EPA to develop a technical
demonstration to reverse this presumption.
b. Final Rule
The EPA is retaining the proposed approach in the final rule.\13\
Under this policy, States are required to address NOX as a
PM2.5 attainment plan precursor and evaluate reasonable
controls for NOX in PM2.5 attainment plans,
unless the State and EPA make a finding that NOX emissions
from sources in the State do not significantly contribute to
PM2.5 concentrations in the relevant nonattainment area.
This presumptive policy is consistent with other recent EPA regulations
requiring NOX reductions which will reduce fine particle
pollution, such as the Clean Air Interstate Rule and a number of rules
targeting onroad and nonroad engine emissions.
---------------------------------------------------------------------------
\13\ The policy is the same as proposed, with the clarification
regarding downwind areas discussed above (Section A.2.b).
---------------------------------------------------------------------------
Technical demonstrations that would reverse the presumption should
be developed in advance of the attainment demonstration and are
discussed in section II.A.8 below.
c. Comments and Responses
Comment: Most commenters generally agreed with the proposed
inclusion of NOX as a presumptive PM2.5
attainment plan precursor.
Response: The EPA agrees with these commenters.
Comment: Some commenters requested guidance on what would
constitute an acceptable demonstration to reverse the presumption that
NOX is a PM2.5 attainment plan precursor.
Response: Guidance on technical demonstrations to reverse the
presumptive inclusion of NOX in all state implementation
plans is discussed in section II.A.8 below.
Comment: One commenter raised concerns that the proposed policy for
NOX would allow a State to find NOX to be an
insignificant contributor to an area's PM2.5 nonattainment
problem and effectively keep the State from controlling the area's
NOX emissions for other purposes, such as to address
interstate transport under section 110 of the CAA. Section 110 requires
SIPs to prohibit emissions within the State that would contribute
significantly to another State's nonattainment problem or interfere
with another State's maintenance plan.
Response: The identification of precursors for regulation under
this rule is for purposes of PM2.5 nonattainment and
maintenance plans under Part D of the CAA. The PM2.5
implementation rule does not prevent a State from regulating
NOX sources under any other Federal or State rule, including
interstate transport rules under Section 110.
6. Policy for SO2
[Section II.E.2 of November 1, 2005 proposed rule (70 FR 65999);
sec. 51.1002 in draft and final regulatory text.]
a. Background
Sulfur dioxide is emitted mostly from the combustion of fossil
fuels in boilers operated by electric utilities and other industry.
Less than 20 percent of SO2 emissions nationwide are from
other sources, mainly other industrial processes such as oil refining
and pulp and paper production. The formation of sulfuric acid from the
oxidation of SO2 is an important process affecting most areas in
North America. There are three different pathways for this transformation.
First, gaseous SO2 can be oxidized by the hydroxyl
radical (OH) to create sulfuric acid. This gaseous SO2 oxidation
reaction occurs slowly and only in the daytime. Second, SO2 can
[[Page 20595]]
dissolve in cloud water (or fog or rain water), and there it can be
oxidized to sulfuric acid by a variety of oxidants, or through
catalysis by transition metals such as manganese or iron. If ammonia is
present and taken up by the water droplet, then ammonium sulfate will
form as a precipitate in the water droplet. After the cloud changes and
the droplet evaporates, the sulfuric acid or ammonium sulfate remains
in the atmosphere as a particle. This aqueous phase production process
involving oxidants can be very fast; in some cases all the available
SO2 can be oxidized in less than an hour. Third,
SO2 can be oxidized in reactions in the particle-bound water
in the aerosol particles themselves. This process takes place
continuously, but only produces appreciable sulfate in alkaline (dust,
sea salt) coarse particles. Oxidation of SO2 has also been
observed on the surfaces of black carbon and metal oxide particles.
During the last 20 years, much progress has been made in understanding
the first two major pathways, but some important questions still remain
about the smaller third pathway. Models indicate that more than half of
the sulfuric acid in the eastern United States and in the overall
atmosphere is produced in clouds.
The sulfuric acid formed from the above pathways reacts readily
with ammonia to form ammonium sulfate,
(NH4)2SO4. If there is not enough
ammonia present to fully neutralize the produced sulfuric acid (one
molecule of sulfuric acid requires two molecules of ammonia), part of
it exists as ammonium bisulfate, NH4HSO4 (one
molecule of sulfuric acid and one molecule of ammonia) and the
particles are more acidic than ammonium sulfate. In certain situations
(in the absence of sufficient ammonia for neutralization), sulfate can
exist in particles as sulfuric acid, H2SO4.
Sulfuric acid often exists in the plumes of stacks where
SO2, SO3, and water vapor are in much higher
concentrations than in the ambient atmosphere, but these concentrations
become quite small as the plume is cooled and diluted by mixing.
Because sulfate is a significant contributor (e.g. ranging from 9
percent to 40 percent) to PM2.5 concentrations in
nonattainment areas and to other air quality problems in all regions of
the country, EPA proposed that States would be required to address
sulfur dioxide as a PM2.5 attainment plan precursor in all areas.
b. Final Rule
The final rule includes the same policy for sulfur dioxide as in
the proposal. States are required to address sulfur dioxide as a
PM2.5 attainment plan precursor and evaluate SO2
for possible control measures in all areas. Sulfate is an important
precursor to PM2.5 formation in all areas, and has a strong
regional impact on PM2.5 concentrations. This policy is
consistent with past EPA regulations, such as the CAIR, the Clean Air
Visibility Rule, the Acid Rain rules, and the Regional Haze rule, that
require SO2 reductions to address fine particle pollution
and related air quality problems.
Under the transportation conformity program, sulfur dioxide is not
required to be addressed in transportation conformity determinations
before a SIP is submitted unless either the state air agency or EPA
regional office makes a finding that on-road emissions of sulfur
dioxide are significant contributors to the area's PM2.5
problem. Sulfur dioxide would be addressed after a PM2.5 SIP
is submitted if the area's SIP contains an adequate or approved motor
vehicle emissions budget for sulfur dioxide. EPA based this decision on
the de minimis level of sulfur dioxide emissions from on-road vehicles
currently, and took into consideration the fact that sulfur dioxide
emissions from on-road sources will decline in the future due to the
implementation of requirements for low sulfur gasoline (which began in
2004) and for low sulfur diesel fuel (beginning in 2006). For more
information, see the May 6, 2005 transportation conformity rule on
PM2.5 precursors at 70 FR 24283.
c. Comments and Responses
Comment: Most commenters agreed with the proposed policy for
SO2. One commenter stated, ``* * * requiring states to
address sulfur dioxide in attainment planning in all areas is
consistent with the science of PM2.5 formation and essential
to effective implementation of the PM2.5 NAAQS.'' Another
commenter concluded that EPA's proposal ``* * * is justified based on
the fact that SO2 has been found to be a significant
contributor to PM2.5 nonattainment in all areas.''
Response: The EPA agrees with these comments.
Comment: Some commenters believe States should be able to make a
demonstration that SO2 not be addressed as an attainment
plan precursor. The commenters claim that the urban increment of
sulfate is generally small, and SO2 control will not matter
in many areas. Commenters also note that a large percentage of the
SO2 emission inventory is being reduced and will be reduced
further through existing programs, and that if attainment can be
demonstrated without additional SO2 controls, a State should
be allowed to make that demonstration in its SIP. One commenter stated
that whether SO2 emissions from a given source located in a
nonattainment area in fact contribute significantly to ambient
concentrations of sulfate and PM2.5 in that nonattainment
area likely will depend on a range of factors, including source type,
stack height, location, and meteorology. The commenter asserted that
sulfate forms over significant geographic distances from the source of
the SO2 emissions and may not form significant
concentrations of PM2.5 in the local nonattainment area.
Response: As in the proposal, the final rule requires
SO2 to be considered a PM2.5 attainment plan
precursor in all cases. Sulfate is a significant fraction of
PM2.5 mass in all nonattainment areas currently, and
although large SO2 reductions are projected from electric
generating units with the implementation of the CAIR program, sulfate
is still projected to be a key contributor to PM2.5
concentrations in the future. SO2 emissions also lead to
sulfate formation on both regional and local scales. The EPA agrees
that the extent of the contribution from a particular source in a
nonattainment area to PM2.5 concentrations in the area will
depend on a number of factors, and that at times the reaction of
SO2 emissions in the atmosphere to form sulfate particles
may occur less rapidly and extend over a significant distance. However,
at other times the conversion of SO2 to sulfate can occur
rapidly and local impacts from a particular source can be more
significant. States are required to develop plans to attain as
expeditiously as practicable through the identification of technically
and economically feasible control measures from the full range of
source categories contributing to PM2.5 nonattainment areas.
In developing these plans, each State will need to consider whether
controls on local SO2 sources would be cost-effective and
would be needed to attain expeditiously.
7. Policy for Direct PM
[Section II.E.2 of November 1, 2005 proposed rule (70 FR 65999);
sec. 51.1002 in draft and final regulatory text.]
a. Background
This section addresses inorganic and organic forms of directly
emitted PM. Although these direct emissions are by definition not
precursors to PM2.5, this section is included to provide
information on the full range of
[[Page 20596]]
components that commonly make up fine particulate matter.
The main anthropogenic sources of inorganic (or crustal) particles
are: entrainment by vehicular traffic on unpaved or paved roads;
mechanical disturbance of soil by highway, commercial, and residential
construction; and agricultural field operations (tilling, planting and
harvesting). Industrial processes such as quarries, minerals
processing, and agricultural crop processing can also emit crustal
materials. While much of these emissions are coarse PM, the size
distribution can have a tail of particles smaller than PM2.5.
In general, coarse PM is most important close to the source, and
not generally a significant contributor to regional scale PM problems.
Even so, during certain high wind events, fine crustal PM has been
shown to be transported over very long distances.
Emission estimates of mechanically suspended crustal PM from
sources within the U.S. are often quite high. However, this PM is often
released very close to the ground, and with the exception of windblown
dust events, thermal or turbulent forces sufficient to lift and
transport these particles very far from their source are not usually
present. Thus, crustal material is only a minor part of
PM2.5 annual average concentrations.
Primary carbonaceous particles are largely the result of incomplete
combustion of fossil or biomass fuels. This incomplete combustion
usually results in emissions of both black carbon and organic carbon
particles. High molecular weight organic molecules (i.e., molecules
with 25 or more carbon atoms) are either emitted as solid or liquid
particles, or as gases that rapidly condense into particle form. These
heavy organic molecules sometimes are referred to as volatile organic
compounds, but because their characteristics are most like direct PM
emissions, they will be considered to be primary emissions for the
purposes of this regulation. Primary organic carbon also can be formed
by condensation of semi-volatile compounds on the surface of other
particles.
The main combustion sources emitting carbonaceous PM2.5
are certain industrial processes, managed burning, wildland fires, open
burning of waste, residential wood combustion, coal and oil-burning
boilers (utility, commercial and industrial), and mobile sources (both
onroad and nonroad). Certain organic particles also come from natural
sources such as decomposition or crushing of plant detritus. Most
combustion processes emit more organic particles than black carbon
particles. A notable exception to this is diesel engines, which
typically emit more black carbon particles than organic carbon. Because
photochemistry is typically reduced in the cooler winter months for
much of the country, studies indicate that the carbon fraction of PM
mass in the winter months is likely dominated by direct PM emissions as
opposed to secondarily formed organic aerosol.
Particles from the earth's crust may contain a combination of
metallic oxides and biogenic organic matter. The combustion of surface
debris will likely entrain some soil. Additionally, emissions from many
processes and from the combustion of fossil fuels contain elements that
are chemically similar to soil. Thus, a portion of the emissions from
combustion activities may be classified as crustal in a compositional
analysis of ambient PM2.5. The proposed rule required that
States address the direct emissions of particulate matter in their
PM2.5 attainment plans. During the comment period, EPA
received several comments regarding the definition of what should be
regulated as ``direct PM2.5.''
b. Final Rule
This rule defines direct PM2.5 emissions as ``air
pollutant emissions of direct fine particulate matter, including
organic carbon, elemental carbon, direct sulfate, direct nitrate, and
miscellaneous inorganic material (i.e. crustal material).'' Development
of attainment plans will include direct PM2.5 emissions and
specific PM2.5 attainment plan precursors.
c. Comments and Responses
Comment: A few commenters noted that 40 CFR 51.1000 of the proposed
rule includes definitions for both ``direct PM2.5
emissions'' and for ``PM2.5 direct emissions.'' They
recommend including just one definition in the final rule.
Response: The EPA acknowledges this oversight and has included in
the final rule a single definition for ``direct PM2.5
emissions.'' It reads: ``Direct PM2.5 emissions means solid
particles emitted directly from an air emissions source or activity, or
gaseous emissions or liquid droplets from an air emissions source or
activity which condense to form particulate matter at ambient
temperatures. Direct PM2.5 emissions include elemental
carbon, directly emitted organic carbon, directly emitted sulfate,
directly emitted nitrate, and other inorganic particles (including but
not limited to crustal material, metals, and sea salt).''
8. Optional Technical Demonstrations for NOX, VOC, and Ammonia
[Section II.E.2 of November 1, 2005 proposed rule (70 FR 65999);
sec. 51.1002 in draft and final regulatory text.]
a. Background
The proposed rule required States to evaluate and consider control
strategies for sources of SO2 and direct PM2.5
emissions in all nonattainment areas. For the precursors
NOX, VOC, and ammonia, the proposed rule included
presumptive policies that could be reversed with an acceptable
technical demonstration by the State or EPA. (The policy in the
proposal presumptively required that NOX emissions must be
addressed in all areas, and that VOC and ammonia emissions do not need
to be addressed in all areas.) A number of commenters requested
additional guidance on the criteria for an acceptable technical
demonstration.
b. Final Rule
The final rule retains provisions for the State or EPA to conduct a
technical demonstration to reverse the presumptive inclusion of
NOX or to reverse the presumptive exclusions of ammonia and
VOC as PM2.5 attainment plan precursors. Demonstrations to
reverse the presumptions for ammonia, VOC, or NOX are to be
based on the weight of evidence of available information, and any
demonstration by the State must be approved by EPA. The State must
demonstrate that based on the sum of available technical and scientific
information, it would be appropriate for a nonattainment area to
reverse the presumptive approach for a particular precursor. The
demonstration should include information from multiple sources,
including results of speciation data analyses, air quality modeling
studies, chemical tracer studies, emission inventories, or special
intensive measurement studies to evaluate specific atmospheric
chemistry in an area.
Because of the variation among nonattainment areas in terms of such
factors as local emissions sources, growth patterns, topography, and
severity of the nonattainment problem, EPA believes that it would not
be appropriate to define a prescriptive set of analyses that must be
included in all PM2.5 precursor technical demonstrations.
The key criterion is that any technical demonstration must fairly
represent available information.
In developing the implementation plan for a nonattainment area, the
State should use all relevant information
[[Page 20597]]
available (from EPA, the State, or other sources) to determine the
scientifically most appropriate approach to regulating NOX,
ammonia, and VOC emissions in the area. As required under any State
rulemaking process, the State must consider and provide a response in
the record to any information or evidence brought forward by commenters
during the SIP planning, development and review process which indicates
that the presumption for a precursor should be reversed. In its review
of the forthcoming State implementation plan submittal, EPA will review
the State's proposed precursor policies in light of all currently
available information. If information brought forward by commenters or
the State in the SIP development process shows that the presumption in
this rule for ammonia, VOC or NOX is not technically
justified for a particular nonattainment area, the State must conduct a
technical demonstration to reverse the presumption. In the case of
ammonia or VOC, the State then would evaluate control measures and
implement those measures that are technically and economically feasible
and that will contribute to expeditious attainment of the standards.
In the section below we suggest examples of the types of analyses
that would be appropriate to use in developing such a demonstration.
States are encouraged to consult with EPA in formulating appropriate
technical demonstrations.
i. Emission Inventory Information: An analysis might show that a
precursor composes a significant fraction of the emissions inventory in
an area and therefore requires greater consideration.
Example: Several stationary sources emitting particular VOCs
known to contribute to SOA formation make up a significant portion
of the area's VOC inventory. This analysis may be useful in conjunction
with other analyses included in a weight of evidence demonstration.
ii. Speciation Data Information: Analysis of data from speciation
networks might lead a State to determine the relative importance of a
precursor to seasonal or yearly average PM concentrations. Individual
precursors require different approaches. Collection of new data could
be used to understand the impacts of precursors in an area.
Example: Nitrate ion is a large portion of winter average
PM2.5 mass. Nitrate ion is a major portion of
PM2.5 mass on the 10 highest PM2.5 days in
winter in the past 3 years. The days with the highest mass
concentrations might be indicative of inversion conditions and/or
local impacts, rather than large-scale transport processes. For these
reasons, nitrate should be addressed in the PM2.5 attainment plan.
Example: Ammonium ion data combined with total calculated
nitrate data indicates that reductions in ammonia would reduce PM
concentrations without a sharp related increase in particle acidity.
PM speciation data shows that PM in the area is generally within 10%
of calculated neutralization. In places for which the needed
atmospheric data are available to determine whether increased
acidity is estimated to lead to negative environmental effects,
analysis showing that increased acidity of particles and
precipitation would likely result from ammonia reductions would
support the presumption against ammonia regulation. Analysis showing
that ammonia reductions would be unlikely to increase the acidity of
particles and precipitation, and that potential reductions in
ammonia would significantly reduce PM2.5 levels, would
support a technical demonstration to reverse the presumption.
iii. Modeling Information: Results of atmospheric modeling may help
a State characterize the impacts of potential precursor emission
reductions on PM2.5 concentrations in an area.
Example: Modeling of SO2, NOX, and VOC
emission reductions result in lower sulfate and nitrate levels but
not lower secondary organic aerosol levels. This likely indicates
that VOC reductions are not as vital as reductions of the other precursors.
Example: Modeled reductions of NOX show a potential
increase in sulfate formation through disruption of the ozone cycle.
SO2 reductions may be a better choice than NOX reductions.
Example: Modeled ammonia reductions show a projected reduction
in PM2.5 concentrations in selected areas. Although
dependant on good quality inventory data, this type of an analysis
would indicate that the area is ammonia-limited and that ammonia
reductions may be beneficial.
Example: Modeling shows that reductions in SO2 in the
absence of NOX reductions in an area will not result in a
significant PM2.5 reduction because more nitrate
particles form when less SO2 is available for particle
formation. However, PM2.5 reductions are significant when
both SO2 and NOX are reduced concurrently.
This analysis would indicate that NOX reductions should
be included in the PM2.5 attainment plan for the area.
iv. Monitoring, Data Analysis, or Other Special Studies: Could
include monitoring of gases and compounds not typically monitored under
the PM2.5 speciation network, receptor modeling analysis, or
special monitoring studies.
Example: Data from specialized monitoring studies can provide
insights about concentrations of ammonia gas and nitric acid in an
area and whether the area is ammonia-limited or not. Ammonia
reductions in ammonia-limited areas typically yield reductions in
PM2.5 concentrations. Specialized monitoring and
laboratory studies can also assess the relative concentrations of
organic compounds and provide insights into the contributions of
different anthropogenic and biogenic VOCs to secondary organic
aerosol formation.
Example: Receptor modeling and statistical analysis
PM2.5 speciation monitoring data can indicate relative
contributions to PM2.5 mass from sources with different
chemical ``fingerprints.''
Example: Additional analysis of organic compounds on filters
collected through speciation monitoring may reveal insights about
the relative degree of carbonaceous material considered to be from
fossil fuel combustion as opposed to combustion of ``modern''
material (such as wood or biomass).
c. Comments and Responses
Comment: A number of commenters requested that the final rule
include guidance on acceptable technical demonstrations.
Response: The above section includes examples designed to help
States formulate appropriate demonstrations. Prescribing specific
technical indicators to be used in all areas would ignore the
scientific uncertainty inherent in the relationships between precursor
emissions and the responses of atmospheric concentrations of
PM2.5. Therefore, States are encouraged to review available
information and consult with EPA in formulating technical
demonstrations appropriate to a particular area.
B. No Classification System
1. No Classification System
a. Background
Section 172 of subpart 1 contains the general requirements for SIPs
for all nonattainment areas. Section 172(a)(1) states that on or after
the date of designation, the Administrator may classify an area for the
purpose of applying an attainment date or for some other purpose. Thus,
a classification system is allowed under section 172 of the CAA, but is
not required for the purposes of implementing a national ambient air
quality standard. The CAA also states that EPA may consider certain
factors in making a decision concerning classification for areas, such
as the severity of nonattainment in such areas, and the availability
and feasibility of the pollution control measures that may be needed to
achieve attainment. In the proposed rule, EPA provided two
implementation approaches for classifying PM2.5
nonattainment areas. Under the first approach, there would be no
classification system. Under the second approach, a two-tiered
classification system would apply, with areas classified as either
``moderate'' or ``serious'' based on specific criteria.
[[Page 20598]]
For example, the two classification tiers could be based on the
severity of nonattainment (e.g., serious areas would be those with a
design value above a specific threshold), or on the attainment date for
the area (e.g., serious areas would be those with attainment dates
after April 2010). However, any moderate area that needs an attainment
date longer than 5 years would be reclassified as serious. This would
ensure that areas with a more persistent PM2.5 problem are
subject to more stringent requirements, even if they are not one of the
areas with the highest current design values. For such areas, the State
would be required to request reclassification for an area and ensure
that the 2008 attainment SIP submission for the area includes all
measures needed to meet the serious area requirements. Under the two
tiered classification approach, we proposed that serious
PM2.5 nonattainment areas would be required to meet the more
stringent requirements than moderate areas that would be defined in
this rulemaking action (e.g., lower thresholds for RACT, fixed
percentage reduction for RFP, etc.). For serious areas, the attainment
date would be as expeditious as practicable, but no later than 10 years
after designation, depending on the year in which the area would be
projected to attain considering existing control requirements and the
effect of RACM, RACT and RFP.
b. Final Rule
The EPA believes that in the case of PM2.5, the no-
classification approach is the most appropriate approach. An advantage
of this approach is that it provides a relatively simple implementation
structure for State implementation of the PM2.5 standards,
and avoids the need to define a classification system and determine
classifications for each area. Without classifications, this rule still
requires that that SIPs include all reasonable measures that contribute
to achieving attainment as expeditiously as practicable. (Further
detail is provided in sections D. and F. below.) Because of differences
in the nature and sources of the PM2.5 problem in different
parts of the country, EPA did not find it appropriate to establish a
tiered classification system with increasing control measure
requirements. The no-classifications approach provides States with
greater flexibility to determine the control strategies that will be
most effective and efficient in bringing specific areas into attainment
as expeditiously as practicable. In addition, EPA believes that States
requesting additional time to attain the standard beyond the initial 5
year attainment date, provided for under Subpart I, will need to adopt
additional or more stringent measures to meet their obligations for
RACT, RACM and attainment that is as expeditious as practicable. We
believe that this addresses the main concerns of those commenters who
contend that a two tiered classification system should be implemented.
c. Comments and Responses
Comment: The majority of the commenters who commented on this issue
stated that they agreed with EPA's preferred no classification
approach. These commenters generally stated that they believed that EPA
has the authority not to establish a classification system for
PM2.5 nonattainment areas. Some commenters stated that it
would also be unreasonable, at this point in the process, for EPA to
implement a classification scheme for the PM2.5 standard.
Many commenters support the no classification approach because it
provides for a simple implementation structure and/or allows greater
implementation flexibility to States, including flexibility to address
specific problems related to individual nonattainment areas in the most
cost-effective and expeditious manner, rather than through a one size
fits all approach. Other commenters stated that they believe that a
classification system is not needed because nonattainment areas in the
Eastern United States are likely to attain the standard within a timeframe
that is consistent with the timeframe established under Subpart 1.
Response: The EPA agrees with these commenters.
Comment: Several commenters disagreed with EPA's preferred approach
and agreed with the two tiered classification approach featuring a
``moderate'' and a ``serious'' area classification. These commenters
also stated that the threat of reclassification or ``bump up'' to a
higher classification was a powerful incentive for areas to attain as
expeditiously as practicable. Commenters also indicated that areas
needing more time to attain the standard should be required to
implement more stringent measures or mandatory measures.
Response: The EPA agrees that areas with more severe nonattainment
problems will need to implement more stringent measures to attain.
However, EPA does not believe that a classification system is needed to
ensure that such measures are implemented. The EPA believes that on
balance the no classification approach is the most appropriate
classification option for the implementation of the PM2.5
standard because of the difference in contributing sources from area to
area.
Comment: Several commenters stated that under EPA's preferred
approach, each State would be required to submit an attainment
demonstration proposing an attainment date that is ``as expeditious as
practicable'' for each area. They asserted that to allow States to
propose their own attainment dates would invite delay in the process of
cleaning up fine particle pollution. These commenters further stated
that States would have no incentive to set an attainment date earlier
than the outer limit set by EPA, even if it would be practicable to
attain the NAAQS sooner.
Response: Section 172 of the CAA requires SIPs to demonstrate
attainment as expeditiously as practicable regardless of whether there
is a classification system, and under this rule states must justify
that their attainment date is as expeditious as practicable considering
all reasonable measures. As noted above, EPA believes that States
requesting additional time to attain the standard beyond the initial 5
year attainment date will need to adopt additional or more stringent
measures to meet their obligations for RACT and RACM and to attain as
expeditiously as practicable. More details on the analytical process
required for an attainment demonstration is included in section II.F.
Comment: Several commenters stated that the CAA requires regulation
of the PM2.5 standard under Subpart 4 of Part D. These
commenters state that EPA takes the position that it must regulate
PM2.5 under Subpart 1 of the CAA, which applies to
nonattainment areas in general. The commenters state that section 7513,
in Subpart 4 of Part D of the CAA, contains specific provisions for
classification of particulate matter nonattainment areas, and that EPA
must therefore regulate PM2.5 under Subpart 4, which
requires a moderate and serious area classification system. Other
commenters argued that implementation of the PM2.5 standard
must proceed under Subpart 1 of Part D of Title I of the CAA and cannot
be governed by Subpart 4 of Part D, which addresses the implementation
of the PM10 standard which is a different pollutant than
PM2.5.
Response: The EPA finds that the PM2.5 standard should
be implemented under subpart I of the CAA, which is the general
provision of the CAA related to NAAQS implementation. Part D of Title I
of the CAA sets forth the requirements for SIPs needed to attain the
national ambient air quality standards. Part D also includes a general
provision under
[[Page 20599]]
Subpart I which applies to all NAAQS for which a specific subpart does
not exist. Because the PM2.5 standards were not established
until 1997, the plan provisions found in section 172 of subpart 1
pertaining to plans for nonattainment areas apply. The EPA further
agrees with comments stating that subpart 4 on its face applies only to
the PM10 standard. In general, the emphasis in subpart 4 on
reducing PM10 concentrations from certain sources of direct
PM2.5 emissions can be somewhat effective in certain
PM2.5 nonattainment areas but not in all. Contributions to
PM2.5 concentrations are typically from a complex mix of
sources of primary emissions and sources of precursor emissions which
form particles through reactions in the atmosphere. PM2.5
also differs from PM10 in terms of atmospheric dispersion
characteristics, chemical composition, and contribution from regional
transport.
2. Rural Transport Classification Option
a. Background
The 8-hour ozone implementation program includes a ``rural
transport classification'' for subpart 1 nonattainment areas. In the
proposal for this rule we discussed whether an area classification of
this type would be appropriate for the PM2.5 implementation
program in light of the fact that no currently designated PM2.5
nonattainment area met the criteria similar to those that apply to rural
transport areas under the ozone implementation program.
As addressed in the proposal, a PM2.5 nonattainment area
would qualify for the ``rural transport'' classification if it met
criteria similar to those specified for rural transport areas for the
1-hour ozone standard under section 182(h). Section 182(h) defines
``rural transport'' areas as those areas that do not include, and are
not adjacent to, any part of a Metropolitan Statistical Area (MSA) or,
where one exists, a Consolidated Metropolitan Statistical Area (CMSA).
Section 182(h) further limits the category to those areas whose own
emissions do not make a significant contribution to pollutant
concentrations in those areas, or in other areas.
As discussed in the preamble to the proposed rule, potential
criteria for a State to identify an area for a rural transport
classification under the PM2.5 program could be similar to
the criteria used in the ozone implementation program: A State with a
PM2.5 ``rural transport'' area would need to (1) demonstrate
that the area meets the above criteria, (2) demonstrate using EPA
approved attainment modeling that the nonattainment problem in the area
is due to the ``overwhelming transport'' of emissions from outside the
area, and (3) demonstrate that sources of PM2.5 and its
precursor emissions within the boundaries of the area do not contribute
significantly to PM2.5 concentrations that are measured in
the area or in other areas.
An area which qualifies for the ``rural transport'' classification
would only be required to adopt local control measures sufficient to
demonstrate that the area would attain the standard by its attainment
date ``but for'' the overwhelming transport of emissions emanating from
upwind States. RFP requirements under subpart 1 would still apply to
these areas. As with other nonattainment areas, rural transport
nonattainment areas would be subject to NSR, transportation conformity,
and general conformity requirements. In the proposal we solicited
comments on whether it would be appropriate to establish less
burdensome NSR requirements in the event that a classification for
rural transport areas is adopted in the final rule. The EPA requested
comment on whether this type of classification option is needed at all
under the PM2.5 implementation program.
b. Final Rule
The final rule does not include a rural transport classification.
This type of classification was included in the CAA for purposes of
implementing the ozone standards because of the phenomenon of the
formation of high ozone levels far downwind in very rural locations,
including on high elevation mountain peaks. In reviewing the currently
designated PM2.5 nonattainment areas, it appears that all
areas but one are within or adjacent to a metropolitan area (i.e. core-
based statistical area or consolidated statistical area), and thus
would not meet the criteria discussed above. Although PM2.5
concentrations are greatly affected by long-range transport of air
pollution, it appears that nonattainment areas typically are located in
urban areas and include significant local pollutant sources.
c. Comments and Responses
Comment: Several commenters stated that they do not support the
adoption of a rural transport classification because it is not needed.
Commenters stated that given the criteria for the rural transport
classification, which greatly limits its applicability, few if any
PM2.5 nonattainment areas can qualify for the option. One
commenter stated that EPA modeled the rural transport classification
after the ``rural transport areas'' provision contained in subpart 2 of
the CAA, which applies only to the ozone standard. The commenter
further states that neither Subpart 1 nor 4 contain any statutory
authority for such a classification.
Response: The EPA believes that it has sufficient statutory
authority under the CAA to establish a rural transport classification,
but we do not believe that such a classification is needed.
Comment: One commenter generally supported the rural transport
concept and the proposed associated requirements, with the addition
that data analysis be included as appropriate in the required technical
demonstrations in addition to modeling. While no PM2.5 area
currently meets the requirements for the rural transport classification
option, several commenters recommended that it be maintained for
potential cases in which the PM2.5 standards are made more
stringent, or measured air quality in areas change in such a way that
areas would qualify for the rural transport classification at a later date.
Response: The EPA does not agree that a rural transport
classification is needed. The EPA will re-evaluate the need for such a
classification as appropriate.
C. Due Dates and Basic Requirements for Attainment Demonstrations
a. Background
Part D of Title I of the CAA sets forth the requirements for SIPs
needed to attain the national ambient air quality standards. Part D
includes a general subpart 1 which applies to all NAAQS for which a
specific subpart does not exist. The 1990 CAA Amendments do not include
any subpart for PM2.5 because the PM2.5 standards
were not yet established. The EPA has determined that for
PM2.5, the nonattainment area plan provisions found in
section 172 of subpart 1 apply.
Section 172(b) of the CAA requires that at the time the Agency
promulgates nonattainment area designations, the EPA must also
establish a schedule for States to submit SIPs meeting the applicable
requirements of section 172(c) and of section 110(a)(2) of the CAA.
Nonattainment area designations were finalized in December 2004, and a
supplemental notice was issued in April 2005. Consistent with section
172(b) of the CAA, 40 CFR 51.1002 of the proposed rule requires the
State to submit its attainment demonstration and SIP revision within 3
years, or by April 2008.
Section 51.1006 of the proposed rule addresses the situation in
which an area
[[Page 20600]]
is initially designated as attainment/unclassifiable but is later
designated as nonattainment based on air quality data after the 2001-
2003 period. Under such circumstances, the SIP submittal date would be
3 years from the effective date of the redesignation, and the
attainment date would be as expeditiously as practicable but no later
than 5 years from the effective date of the redesignation.
The section 172(c) requirements that States are to address under
section 172(c) (including RACT, RACM, RFP, contingency measures,
emission inventory requirements, and NSR) are discussed in later
sections of this document. Section 110(a)(2) of the CAA requires all
States to develop and maintain a solid air quality management
infrastructure, including enforceable emission limitations, an ambient
monitoring program, an enforcement program, air quality modeling, and
adequate personnel, resources, and legal authority. Section
110(a)(2)(D) also requires State plans to prohibit emissions from
within the State which contribute significantly to nonattainment or
maintenance areas in any other State, or which interfere with programs
under part C to prevent significant deterioration of air quality or to
achieve reasonable progress toward the national visibility goal for
Federal class I areas (national parks and wilderness areas). In order
to assist States in addressing their obligations regarding regionally
transported pollution, EPA has finalized the CAIR to reduce
SO2 and nitrogen oxide emissions from large electric
generating units.\14\
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\14\ More information on the Clean Air Interstate Rule (CAIR) is
available at: http://www.epa.gov/cair.
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To date, few states have submitted a SIP revision addressing the
section 110(a)(2) requirements for the purposes of implementing the
PM2.5 standards. The EPA recognizes that this situation is
due in part to the fact that there were a series of legal challenges to
the PM standards which were not resolved until March 2002, at which
time the standards and EPA's decision process were upheld (see section
I.B. for further discussion of past legal challenges to the standards).
To address the States' continuing obligation to address the
requirements of section 110(a), 40 CFR 51.1002 of the proposed rule
also required each State to address the required elements of section
110(a)(2) of the CAA as part of the SIP revision adopting its
attainment plan, if it has not already done so. On March 10, 2005, EPA
entered into a consent decree with Environmental Defense and American
Lung Association concerning EPA's failure to find that States failed to
submit SIPs to address the section 110(a)(2) requirements. As a part of
that consent decree, by no later than October 8, 2008, EPA is required
to publish a notice in the Federal Register related to its determinations
of whether each State has submitted SIPs for PM2.5 that meet
the requirements as stated under section 110(a)(2) of the CAA.
b. Final Rule
The final rule maintains the regulatory approach described above.
c. Comments and Responses
There were no comments on this portion of the proposal.
D. Attainment Dates
1. Background on Statutory Requirements
Establishing attainment dates. Section 172(a)(2) states that an
area's attainment date ``shall be the date by which attainment can be
achieved as expeditiously as practicable, but no later than 5 years
from the date such area was designated nonattainment * * *, except that
the Administrator may extend the attainment date to the extent the
Administrator determines appropriate, for a period no greater than 10
years from the date of designation as nonattainment considering the
severity of nonattainment and the availability and feasibility of
pollution control measures.''
Since PM2.5 designations have an effective date of April
5, 2005, the initial 5-year attainment date for PM2.5 areas
would be no later than April 5, 2010. For an area with an attainment
date of April 5, 2010, EPA would determine whether it had attained the
standard by evaluating air quality data from the three previous
calendar years (i.e. 2007, 2008, and 2009).
For any areas that are granted the full 5 year attainment date
extension under section 172, the attainment date would be no later than
April 5, 2015. For such areas, EPA would determine whether they have
attained the standard by evaluating air quality data from 2012, 2013,
and 2014. Section 51.1004 of the proposed regulations addressed the
attainment date requirement. Section 51.1004(b) provided that in their
attainment demonstrations, States would propose an attainment date
representing attainment as expeditiously as practicable based upon
implementation of existing Federal and State measures, and all new
reasonable local and intrastate measures. The EPA would approve a
particular attainment date based on its review of the attainment
demonstration.
Determining Whether an Area Has Attained. The EPA has the
responsibility for determining whether a nonattainment area has
attained the standard by its applicable attainment date. Section
179(c)(1) of the Act requires EPA to make determinations of attainment
no later than 6 months following the attainment date for the area.
Under section 179(c)(2), EPA must publish a notice in the Federal
Register identifying those areas which failed to attain by the
applicable attainment date. The statute further provides that EPA may
revise or supplement its determination of attainment for the affected
areas based upon more complete information or analysis concerning the
air quality for the area as of the area's attainment date.
Section 179(c)(1) of the Act provides that the attainment
determination for an area is to be based upon an area's ``air quality
data as of the attainment date.'' The EPA will make the determination
of whether an area's air quality is meeting the PM2.5 NAAQS
by the applicable attainment date primarily based upon data gathered
from the air quality monitoring sites which have been entered into
EPA's Air Quality System (AQS) database. No special or additional SIP
submittal will be required from the State for this determination.
A PM2.5 nonattainment area's air quality status is
determined in accordance with appendix N of 40 CFR part 50. To show
attainment of the 24-hour and annual standards for PM2.5,
the most recent three consecutive years of data prior to the area's
attainment date must show that PM2.5 concentrations over a
three-year period are at or below the levels of the standards. A
complete year of air quality data, as described in part 50, Appendix N,
comprises of all 4 calendar quarters with each quarter containing data
from at least 75 percent of the scheduled sampling days. The annual
standard for PM2.5 is attained when the 3-year average
annual mean concentration is less than or equal to 15.05 [mu]g/
m3. The 24-hour standard for PM2.5 is met when
the average of 98th percentile values for three consecutive calendar
years at each monitoring site is less than or equal to 65.5 [mu]g/m3.
The EPA will begin processing and analyzing data related to the
attainment of PM2.5 areas immediately after the applicable
attainment date for the affected areas. Current EPA policy, under 40
CFR part 58, sets the deadline for submittal of air quality data into
the AQS database for no later than 90 days after the end of the
calendar year.
[[Page 20601]]
While EPA may determine that an area's air quality data indicates
that an area may be meeting the PM2.5 NAAQS for a specified
period of time, this does not eliminate the State's responsibility
under the Act to adopt and implement an approvable SIP. If EPA
determines that an area has attained the standard as of its attainment
date, the area will remain classified as nonattainment until the State
has requested, and EPA has approved, redesignation to attainment for
the area.
In order for an area to be redesignated as attainment, the State
must comply with the five requirements listed under section
107(d)(3)(E) of the Act. This section requires that:
--EPA has determined that the area has met the PM2.5 NAAQS;
--EPA has fully approved the state's implementation plan;
--The improvement in air quality is due to permanent and enforceable
reductions in emissions;
--EPA has fully approved a maintenance plan for the area;
--The State(s) containing the area have met all applicable requirements
under section 110 and part D.
2. Establishing Attainment Dates
a. Background
The EPA proposed rule language on attainment dates that closely
tracks the statutory language. In the preamble, EPA noted that the
attainment date that is as expeditious as practicable should reflect
the projected impact of existing national and State programs (e.g.
partial implementation of the CAIR rule, final Acid Rain Program, motor
vehicle tier II standards and heavy-duty diesel engine standards,
NOX SIP call, State legislation such as Clean Smokestacks
bill in North Carolina) as well as additional reasonable measures
required for the PM2.5 nonattainment SIP.
With respect to its authority to extend an area's date beyond 5
years, EPA stated in the preamble that the State can submit a SIP
demonstrating that it is impracticable to attain by the 5-year
attainment date: ``As stated previously, under section 172(a)(2)(A),
EPA may grant an area an extension of the initial attainment date for a
period of one to 5 years. States that request an extension of the
attainment date under this provision of the CAA must submit a SIP by
April 5, 2008 that includes, among other things, an attainment
demonstration showing that attainment within 5 years of the designation
date is impracticable. It must also show that the area will attain the
standard by an alternative date that is as expeditious as practicable,
but in no case later than 10 years after the designation date for the
area (i.e. by April 5, 2015 for an area with an effective designation
date of April 5, 2005). An appropriate extension in some cases may be
only 1 or 2 years--a 5-year extension is not automatic upon request.
The attainment demonstration must provide sufficient information to
show that attainment by the initial attainment date is impracticable
due the severity of the nonattainment problem in the area, the lack of
available control measures, and any other pertinent information related
to these statutory criteria. States requesting an extension of the
attainment date must also demonstrate that all local control measures
that are reasonably available and technically feasible for the area are
currently being implemented to bring about expeditious attainment of
the standard by the alternative attainment date for the area. The
State's plan will need to project the emissions reductions expected due
to Federally enforceable national standards, State regulations, and
local measures such as RACT and RACM, and then conduct modeling to
project the level of air quality improvement in accordance with EPA's
modeling guidance. The EPA will not grant an extension of the
attainment date beyond the initial 5 years required by section
172(a)(2)(A) for an area if the State has not considered the
implementation of all RACM and RACT local control measures for the area
(see section III.I for a more detailed discussion of RACT and RACM).
The EPA also will examine whether the State has adequately considered
measures to address intrastate transport of pollution from sources
within its jurisdiction. In attainment planning, States have the
obligation and authority to address the transport of pollution from one
area of the State to another. Any decision made by EPA to extend the
attainment date for an area beyond its original attainment date will be
based on facts specific to the nonattainment area at issue and will
only be made after providing notice in the Federal Register and an
opportunity for the public to comment.''
b. Final Rule
We are adopting the approach described above from the proposed
rule. We also wish to clarify language that was in the preamble to the
proposed rule regarding the criteria for an extension. The preamble
stated that attainment date extensions would be based on the two
statutory extension criteria--``the severity of nonattainment, and the
availability and feasibility of pollution control measures,''--as well
as ``other pertinent information which shows that additional time is
required for the area to attain the standard.'' The CAA does not
include this third clause and the regulatory text for the final rule
does not include this third clause. The intent of this language in the
preamble to the proposal was that States could include ``other
pertinent information'' related to the two statutory criteria.
c. Comments and Responses
Comment: Some commenters expressed concern that EPA's preamble
language appeared to assert a new basis for granting extensions not
provided by the statute. They said EPA has authority to extend the
attainment date under Section 7502(a)(2) based solely on consideration
of two enumerated factors: the severity of nonattainment, and the
availability and feasibility of control measures.
Response: The EPA agrees that extensions must be based upon the two
factors in the statute, which are quite broad. A clarification of the
preamble phrase cited by the commenter is provided above. The phrase in
question--``any other pertinent information which shows that additional
time is required for the area to attain the standard''--refers to
information that relates to the two statutory factors.
Comment: One commenter stated that an area should qualify for an
extension only if the area will implement stringent local controls, yet
still cannot practicably attain by the five-year deadline. The
commenter stated that at a minimum, EPA must require states to adopt
RACM for both mobile and stationary sources before granting an
extension. Another commenter said that given the difficulty many areas
will have in meeting the five-year deadline for attainment of the
PM2.5 NAAQS (and especially in light of the fact that the
deadline occurs only 2 years after states are to submit attainment
SIPs), EPA should provide maximum flexibility in allowing extensions to
the full 10-year period.
Response: The EPA agrees that extensions should be granted only if
an area cannot practicably attain within 5 years despite application of
all reasonable measures, including RACM. Although some measures can be
implemented within a year or two, many measures require a longer period
for installation of controls or full program implementation. In light
of the limited time period between the SIP submittal deadline and the
5-year date, EPA believes that a significant number of areas may
warrant extensions ranging from one to 5 years, with the length of
[[Page 20602]]
extension depending on the factors described above.
Comment: One commenter advocated that EPA include in this final
rule a determination of those areas for which attainment within 5 years
is impracticable. Another commenter advocated that EPA establish
guidance based on EPA national modeling conducted last year to
establish 2015 as constituting expeditious attainment for certain areas.
Response: The EPA is not determining in this rulemaking the areas
that should receive extensions or should receive the maximum 10-year
attainment date, for several reasons. First, EPA did not propose such
an approach. Therefore, the public has not had the opportunity to
comment on the approach or on the technical information on which EPA
would make such judgments.
Second, EPA believes that modeling being conducted by the states,
with updated inventories and finer grids, will generally provide a more
reliable basis for projecting future PM2.5 base case levels
than national modeling conducted by EPA with older information. State
modeling of future year PM2.5 levels that has been conducted
to date indicates that some areas will start closer or farther from the
standard than EPA had projected.
Third, the SIP process provides a forum for states to identify
reasonable controls and conduct analyses to determine the appropriate
attainment date for an area. This process provides for input from
expert stakeholders, the general public, other states which may share
the same multi-State nonattainment area, and EPA on decisions regarding
controls and attainment dates. At this time, EPA does not have the
benefit of this process to inform a judgment as to when areas can
practicably attain. States are responsible for developing RACM
demonstrations; at this time, EPA lacks the information to conduct a
credible RACM demonstration for all PM2.5 nonattainment areas.
Fourth, no State commenter advocated that EPA attempt to make these
judgments on attainment dates in advance of the State SIP process. The
statute gives the states the lead in developing State implementation plans.
Comment: Another commenter recommends that an area should receive
an attainment date extension when collectively the following conditions
have been met:
? It is proven through modeling that the region is adversely
effected by transport of PM2.5 emissions from up wind
sources beyond that State's control;
? A State has submitted and committed to implementing all
Federal PM2.5 emission reduction requirements in a timely
manner; and,
? The extension concept is approved through the State air
agency or through the MPO Interagency Consultation Process at the MPO
level if applicable.
Response: This commenter advocates for attainment date extensions
without any consideration of reasonable local measures. As stated
above, EPA believes that extensions should be granted only if an area
cannot practicably attain within 5 years despite application of all
reasonable measures, including RACM. Although some measures can be
implemented within a year or two, many measures may require a longer
period for installation of controls or full program implementation. In
light of the limited time period between the SIP submittal deadline and
the 5-year date, EPA believes that a significant number of areas may
warrant extensions ranging from one to 5 years, with the length of
extension depending on the factors described above.
3. Attainment Dates: 1-Year Extensions
a. Background
Subpart 1 provides for States to request two 1-year extensions of
the attainment date for a nonattainment area under limited
circumstances. Section 172(a)(2)(C) of the CAA provides that EPA
initially may extend an area's attainment date for 1 year, provided
that the State has complied with all the requirements and commitments
pertaining to the area in the applicable implementation plan, and
provided that the area has had no more than a minimal number of
``exceedances'' of the relevant standard in the preceding year. Because
the PM2.5 standards do not have exceedance-based forms but
are based on 3-year averaging periods, we interpret the air quality
test in 40 CFR 51.1005 to mean that the area would need to have ``clean
data'' for the third of the 3 years that are to be evaluated to
determine attainment.\15\ By this we mean that for the third year, the
air quality for all monitors in the area as analyzed in accordance with
Appendix N to 40 CFR part 50 each must have an annual average of 15.0
[mu]g/m\3\ or less, and a 98th percentile of 24-hour monitoring values
of 65 [mu]g/m\3\ or less in order to qualify for a 1-year extension.
(Given the rounding provisions specified in 40 CFR part 50, Appendix N,
these criteria would be satisfied if the concentrations before final
rounding are less than an annual average of 15.05 [mu]g/m\3\ and a 24-
hour value of 65.5 [mu]g/m\3\.)
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\15\ See section 51.1005 of the proposed regulation.
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For example, suppose an area in violation of the annual standard
has an attainment date of April 2010, and its annual average for 2007
was 15.8 and for 2008 was 15.6. If the annual average for the area in
2009 is 14.9, then the 3-year average would be 15.4, and it would not
have attained the standard. We interpret section 172(a)(2)(C) as
allowing the area to submit a request to EPA for a 1-year extension of
its attainment date to 2011 (provided the State has also complied with
its requirements and commitments) since the 14.9 ambient air quality
value in the third year (2009) met the test of being at or below 15.0.
Section 51.1005(a) of the proposed regulation addresses the initial 1-
year attainment date extension.
The air quality measured in 2010 in conjunction with prior data
will determine if the area attains the standard, qualifies for a second
1-year extension, or does not attain the standard. For example, if the
area's annual average for 2010 is 14.3, then its 3-year average for
2008-2010 would be 14.9 and it would have met the annual standard.
If the area's annual average for 2010 is 14.9, however, then its 3-
year average for 2008-2010 would be 15.1. In this situation the area
would not have attained the standard, but the area would meet the air
quality test for the second of the 1-year extensions allowed under
section 172(a)(2)(C), because the 2010 annual average was at or below
15.0. Section 51.1005(b) of the proposed rule addresses the second 1-
year attainment date extension. After obtaining a second 1-year
extension, the State would evaluate whether the air quality values in 2011,
in conjunction with 2009 and 2010 data, bring the area into attainment.
Pursuant to section 172(a)(2)(C), States must submit additional
information to EPA to demonstrate that they have complied with
applicable requirements, commitments, and milestones in the
implementation plan. This information is needed in order for EPA to
make a decision on whether to grant a 1-year attainment date extension.
The EPA will not be inclined to grant a 1-year attainment date
extension to an area unless the State can demonstrate that it has met
important requirements contained in the area's implementation plan.
States must demonstrate that: (1) Control measures have been submitted
in the form of a SIP revision and substantially implemented to satisfy
the requirements of RACT and RACM for the area, (2) the area has made
emissions reductions progress that
[[Page 20603]]
represents reasonable further progress (RFP) toward attainment of the
NAAQS, and (3) trends related to recent air quality data for the area
indicate that the area is in fact making progress toward attainment of
the standard. Any decision made by EPA to extend the attainment date
for an area will be based on facts specific to the nonattainment area
at issue, and will only be made after providing notice in the Federal
Register and an opportunity for the public to comment.
If an area fails to attain the standard by the attainment date, EPA
would publish a finding to this effect in accordance with section 179
of the CAA. The area then would be required, within 1 year of
publication of this finding, to develop a revised SIP containing
additional emission reduction measures needed to attain the standard as
expeditiously as practicable.
b. Final Rule
The final rule retains the proposed criteria for states to receive
a 1-year attainment date extension for a nonattainment area.
c. Comments and Responses
Comment: A number of commenters supported EPA's ability to grant a
1-year attainment date extension if monitoring data indicate that the
PM2.5 levels during the most recent year were below 15.05 [mu]g/m\3\.
Response: The EPA agrees with these comments.
Comment: Some commenters recommended that a 1-year extension be
provided if the trend line of the area's emissions levels or air
quality data projects attainment in the extension year.
Response: The EPA believes that 1-year extensions should be based
on air quality data, which can be assessed quickly after the end of the
year. Basing such extensions solely on emissions trends would be
impractical due to the longer turnaround time needed to evaluate
emissions changes affecting a monitor.
Comment: One commenter believes the current requirement is overly
stringent and inconsistent with the statute. The commenter believes
that EPA's proposed approach incorrectly defines the statutory language
referring to a ``minimal number of exceedances'' of the standard in the
previous year as ``zero'' exceedances. Alternatively, the commenter
suggests EPA could withdraw this provision and provide more detailed
guidance giving the Agency and states some flexibility to demonstrate
that exceedances were minimal in a given case since nothing in the
statute requires the rigid definition of minimal that EPA proposes.
Response: The EPA believes the policy in the final rule is a
reasonable application of the statutory language to a standard not
based on exceedances. The EPA does not believe it would be appropriate
to provide a 1-year extension to an area with air quality data showing
it violating the standard over the 3 years prior to the attainment year.
4. Achieving ``Clean Data''
a. Background
Section III.D of the preamble to the proposed rule describes the
incentives for attaining the standards prior to April 2008, when SIP
submittals are due, or prior to an area's approved attainment date.
Areas with design values just over the level of the standard may be
able to achieve reductions in the local area or in the State so that,
when their effect is considered in combination with reductions achieved
under national programs, they may be sufficient to attain the standards
before SIPs are due in 2008. For example, if monitoring in a
nonattainment area shows that the air quality for 2004-2006 meets the
standards, then the area may be subject to reduced regulatory
requirements and be redesignated as ``attainment.''
The EPA issued a ``Clean Data'' policy memorandum in December 2004
describing possible reduced regulatory requirements for areas that
attain the standards, but have not yet been redesignated as attainment.\16\
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\16\ Memorandum of December 14, 2004, from Steve Page, Director,
EPA Office of Air Quality Planning and Standards to EPA Air Division
Directors, ``Clean Data Policy for the Fine Particle National
Ambient Air Quality Standards.'' This document is available at:
http://www.epa.gov/pmdesignations/guidance.htm.
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b. Final Rule
In the proposed rule, EPA indicated that it had issued this ``Clean
Data'' policy to apply for purposes of the PM2.5 standards.
In this action EPA is finalizing as a rule the statutory interpretation
that is embodied in the policy. Section 51.1004(c). The text of the
final rule encapsulates the statutory interpretation set forth in the
policy. Determinations as to whether individual areas have attained the
PM2.5 standard and thus qualify for application of the new
clean data rule will be made in the context of rulemakings for those
individual areas.
The preamble to the proposed rule mistakenly stated that if an area
achieved ``clean data,'' it would be ``relieved of the requirements to
implement the nonattainment NSR program otherwise required for
nonattainment areas, and instead would implement the PSD program.'' The
EPA wishes to clarify that the Clean Data Policy does not provide for
suspension of the requirements for NSR nor for RACT. The provisions at
issue in the Clean Data Policy include the requirements for an
attainment demonstration and other related requirements, reasonable
further progress, and contingency measures.
c. Comments and Responses
Comment: One commenter stated that EPA has absolutely no authority
to waive NSR or any of the CAA's other requirements for nonattainment
areas merely because a nonattainment area has 3 years of clean data,
nor does EPA have authority to waive mandatory requirements of the CAA
such as NSR, RACT, and RFP merely because EPA or the State claims they
are not needed for attainment. The commenter believes that the only way
that a nonattainment area can cease implementing controls and
requirements mandated for such areas is to seek and obtain
redesignation to attainment, and demonstrate in the process that the
controls and requirements are not needed for maintenance of standards.
The CAA has explicit procedures and prerequisites for redesignating
nonattainment areas to attainment (CAA sections 107(d)(3)(E) and 175A).
The EPA's ``clean data'' proposal would illegally circumvent those
requirements.
Response: The Clean Data policy does not waive requirements for NSR
nor for RACT. However, EPA believes that ``clean data'' policies for
the ozone and fine particle programs are based on a reasonable
interpretation of the CAA. The Clean Data Policy is the subject of two
EPA memoranda setting forth our interpretation of the provisions of the
Act as they apply to areas that have attained the relevant NAAQS. The
EPA also finalized the statutory interpretation set forth in the policy
in a final rule, 40 CFR 51.918, as part of its Final Rule to Implement
the 8-Hour Ozone National Ambient Air Quality Standard--Phase 2 (Phase
2 Final Rule). See discussion in the preamble to the rule at 70 FR
71645-71646 (November 29, 2005). The legal rationale for the Clean Data
policy is explained in our Phase 2 Final Rule, in our December 14, 2004
memorandum from Stephen D. Page entitled ``Clean Data Policy for the
Fine Particle National Ambient Air Quality Standards'' (Page Memo), and
in our May 10, 1995 memorandum from John S. Seitz, entitled
``Reasonable Further Progress, Attainment
[[Page 20604]]
Demonstration, and Related Requirements for Ozone Nonattainment Areas
Meeting the Ozone National Ambient Air Quality Standard'' (Seitz memo).
We adopt and reiterate those explications here.
The EPA has also explained its rationale for applying the Clean
Data policy in rulemaking actions associated with nonattainment areas
for the PM10 and 1-hour ozone standards. For rulemaking
actions applying the Clean Data policy to the PM10
standards, see 71 FR 27440 (May 11, 2006) (Weirton, WVA), 71 FR 13021
(March 14, 2006) (Yuma, AZ), 71 FR 6352 (February 8, 2006) (Ajo, AZ).
For a discussion of the legal rationale supporting rulemaking actions
applying the Clean Data policy to the 1-hour ozone standards, see, for
example, 67 FR 49600 (July 31, 2002); 65 FR 37879 (June 19, 2000)
Cincinnati-Hamilton, Ohio-Kentucky); 61 FR 20458 (May 7, 1996)
(Cleveland Akron-Lorain, Ohio); 66 FR 53094 (October 19, 2001)
(Pittsburgh-Beaver Valley, Pennsylvania); 61 FR 31832 (June 21, 1996
(Grand Rapids, Michigan); 60 FR 36723 (July 18, 1995) (Salt Lake and
Davis Counties, Utah); 68 FR 25418 (May 12, 2003) (St Louis, Missouri);
69 FR 21717 (April 22, 2004) (San Francisco Bay Area).
The EPA has further elaborated on its legal rationale for the Clean
Data Policy in briefs filed in the 10th, 7th, and 9th Circuits, and
hereby incorporates those briefs insofar as relevant here. See Sierra
Club v. EPA, No. 95-9541 (10th Cir.), Sierra Club v. EPA, No. 03-2839,
03-3329 (7th Cir.), Our Children's Earth Foundation v. EPA, No. 04-
73032 (9th Cir.). As stated in the policy, the attainment
demonstration, RFP requirements, and contingency measure requirement
are designed to bring an area into attainment. Once this goal has been
achieved, it is appropriate to suspend the obligation that States
submit plans to meet these goals, so long as the area continues to
attain the relevant standard. The Tenth, Seventh and Ninth Circuits
have all upheld EPA rulemakings applying the Clean Data Policy. See
Sierra Club v. EPA, 99 F. 3d 1551 (10th Cir. 1996); Sierra Club v. EPA,
375 F. 3d 537 (7th Cir. 2004); Our Children's Earth Foundation v. EPA,
No. 04-73032 (9th Cir. June 28, 2005 (Memorandum Opinion).
The EPA has explained in its memoranda on the Clean Data Policy for
PM2.5 and for ozone that it is reasonable to interpret the
provisions regarding RFP and attainment demonstrations, along with
certain other related provisions, as not requiring further submissions
to achieve attainment for so long as the area is in fact attaining the
standard. Under the policy, EPA is not granting an exemption from any
applicable requirement under Part D. Rather, EPA has interpreted these
requirements as not applying for so long as the area remains in
attainment with the standard. This is not a waiver of requirements that
by their terms apply; it is a determination that certain requirements
are written so as to be operative only if the area is not attaining the
standard.
CAA section 172(c)(2) provides that SIP provisions in nonattainment
areas must require ``reasonable further progress.'' The term
``reasonable further progress'' is defined in section 171(1) as ``such
annual incremental reductions in emissions of the relevant air
pollutant as are required by this part or may reasonably be required by
the Administrator for the purpose of ensuring attainment of the
applicable NAAQS by the applicable date.'' Thus, by definition, the
``reasonable further progress'' provision requires only such reductions
in emissions as are necessary to attain the NAAQS. If an area has
attained the NAAQS, the purpose of the RFP requirement will have been
fulfilled, and since the area has already attained, showing that the
State will make RFP towards attainment will ``have no meaning at that
point.'' The EPA's General Preamble for the Implementation of Title I
of the Clean Air Act Amendments of 1990 (General Preamble) 57 FR 13498,
13564 (April 16, 1992).
CAA section 172(c)(1), the requirement for an attainment
demonstration, provides in relevant part that SIPs ``shall provide for
attainment of the [NAAQS].'' The EPA has interpreted this requirement
as not applying to areas that have reached attainment. If an area has
attained the standard, there is no need to submit a plan demonstrating
how the area will reach attainment. In the General Preamble (57 FR
13564), EPA stated that no other measures to provide for attainment
would be needed by areas seeking redesignation to attainment since
``attainment will have been reached.'' See also Memorandum from John
Calcagni, ``Procedures for Processing Requests to Redesignate Areas to
Attainment,'' September 4, 1992, at page 6.
CAA section 172(c)(9) provides that SIPs in nonattainment areas
``[S]hall provide for the implementation of specific measures to be
undertaken if the area fails to make reasonable further progress, or to
attain the [NAAQS] by the attainment date applicable under this part.
Such measures shall be included in the plan revision as contingency
measures to take effect in any such case without further action by the
State or [EPA].''
This contingency measure requirement is inextricably tied to the
reasonable further progress and attainment demonstration requirements.
Contingency measures are implemented if reasonable further progress
targets are not achieved, or if attainment is not realized by the
attainment date. Where an area has already achieved attainment by the
attainment date, it has no need to rely on contingency measures to come
into attainment or to make further progress to attainment. As EPA
stated in the General Preamble:
``The section 172(c)(9) requirements for contingency measures
are directed at ensuring RFP and attainment by the applicable
date.'' 57 FR 13564. Thus these requirements no longer apply when an
area has attained the standard.
It is important to note that should an area attain the PM2.5
standards based on three years of data, its obligation to submit an
attainment demonstration is not waived but is only suspended. If the
area then has air quality concentrations in the following year such
that the area exceeds the standard for years 2 through 4, then the
area's obligation to submit an attainment demonstration is back in effect.
The determination of attainment contemplated by the Clean Data
Policy does not purport to be a redesignation, and thus the
requirements for redesignation under section 107(d) are not applicable.
Nor does the Clean Data Policy avoid or illegally circumvent the
redesignation requirements of section 107 of the CAA. All of the
requirements for redesignation remain in effect and must be satisfied
for an area to be redesignated. Sierra Club v. EPA, 99 F.3d at 1557-
1558. The Clean Data Policy is simply an interpretation of certain
provisions of the CAA, whose express purpose is to achieve attainment
of the standard, as not requiring SIP revisions to be made by the State
for so long as the area continues to attain the standard. The policy
does not purport to exempt areas from requirements that are
inapplicable only if an area is redesignated to attainment. It
interprets certain provisions which are written in such a way as to
impose requirements only upon areas that are not attaining the NAAQS,
regardless of whether they have been redesignated to attainment. The
EPA has not provided for any waiver from statutory requirements that
was not provided by Congress. The area at issue remains designated
nonattainment, and is subject to the risk that if a violation occurs it
will have to
[[Page 20605]]
adopt and implement reasonable further progress requirements,
contingency measures, and an attainment demonstration, unless it is
redesignated to attainment. In order to be redesignated to attainment,
however, the area will have to satisfy all of the requirements of section
107(d)(3)(E), including the requirement for a long-term maintenance plan.
While a determination of attainment is not equivalent to a
redesignation to attainment, nothing in the Act compels EPA to wait
until an area meets all the requirements for redesignation before EPA
makes a determination that the area is in attainment with the standard,
thereby suspending the requirements for certain provisions related to
attainment. Indeed, section 179(c) of the Act requires EPA to make an
attainment determination within six months after an area's applicable
attainment date whether or not the EPA has made a finding with respect
to redesignation. The EPA's interpretation of the Act's provisions not
to require, once attainment has been reached, certain plan submissions
whose purpose is to assure attainment, is not at odds with the
requirements for redesignation. Nor does EPA's construction of the
statute adversely impact planning for maintenance. An area that is
monitoring attainment, but is still designated as a nonattainment area,
retains strong incentives to seek redesignation to attainment, and
remains subject to the requirement to demonstrate maintenance in order
to be redesignated. For a detailed discussion of the relationship of
redesignation requirements and attainment determinations, see the
discussions in the EPA briefs in Our Children's Earth Foundation v.
EPA, supra at pp. 43-60., Sierra Club v. EPA No. 95-9541 (10th Cir.) at
29-43, and Sierra Club v. EPA Nos. 03-2839, 03-3329 (7th Cir.) at 33-44
which are contained in the docket for this rulemaking.
Comment: A commenter noted that EPA's proposal suggested that areas
attaining the standard would be subject to reduced regulatory
requirements. The commenter believed that EPA's interpretation should
be codified in regulatory form, in order to assure that areas legally
meeting the current PM2.5 standard and those requesting
redesignation be enabled to be redesignated and to benefit from the
interpretation through regulation, rather than by guidance or policy.
Response: The EPA has adopted the commenter's suggested approach of
codifying its Clean Data Policy interpretation for PM2.5 in
regulatory form. Section 51.1004(c). As it did for ozone in its Phase
II Ozone Implementation Rule, EPA is including in this rulemaking a
regulation that encapsulates the statutory interpretation that is
embodied in its Clean Data Policy for PM2.5, set forth
above. As noted in the response to comment above, determinations as to
whether individual areas have attained the PM2.5 standard
and thus qualify for application of the rule will be made in the
context of rulemakings for those individual areas. The EPA believes,
however, that encapsulating its interpretation in regulatory form will
lend clarity and consistency to the process of applying its interpretation.
E. Modeling and Attainment Demonstrations
1. Background
[Section III.F.1 of November 1, 2005 proposed rule (70 FR 66007);
sec 51.1007 in draft and final regulatory text]
As noted in the proposal, Section 172(c) requires States with
nonattainment areas to submit an attainment demonstration. An
attainment demonstration consists of: (1) Technical analyses that
locate, identify, and quantify sources of emissions that are
contributing to violations of the PM2.5 NAAQS; (2) analyses
of future year emissions reductions and air quality improvement
resulting from already-adopted national and local programs, and from
potential new local measures to meet the RACT, RACM, and RFP
requirements in the area; (3) adopted emission reduction measures with
schedules for implementation; and (4) contingency measures required
under section 172(c)(9) of the CAA.
a. Final Rule
The requirements from the proposal are unchanged. Each State with a
nonattainment area will be required to submit a SIP with an attainment
demonstration that includes analyses supporting the State's proposed
attainment date. States must show that the area will attain the
standards as expeditiously as practicable and it must include an
analysis of whether implementation of reasonably available measures
will advance the attainment date.
2. Areas That Need To Conduct Modeling
[Section III.F.2 of November 1, 2005 proposed rule (70 FR 66007)]
a. Background
All nonattainment areas need to submit an attainment demonstration,
but in some cases, States may not need new, local-scale modeling
analyses. In the proposed rule, EPA proposed that States may use in a
PM2.5 attainment demonstration certain local, regional and/
or national modeling analyses that have been developed to support
Federal or local emission reduction programs, provided the modeling
meets the attainment modeling criteria set forth in EPA's modeling
guidance. The proposal also stated that nonattainment areas for which
local, regional, or national scale modeling demonstrates the area will
not attain the standard within 5 years of designation would be required
to submit an attainment demonstration SIP that includes new modeling
showing attainment of the standards as expeditiously as practicable.
b. Final Rule
In the final rule, EPA is reaffirming the potential use of national
and/or regional modeling as part of an attainment demonstration. We are
also clarifying the types of modeling analyses that may be useful as a
``primary'' modeling analysis and as a ``supplemental'' analysis. The
proposal suggested that it may be appropriate, in certain
circumstances, for a State to submit regional or national modeling as
the sole (primary) modeling analysis in its attainment demonstration.
This implies that the State would not need to conduct local modeling
analyses. We wish to further define the differences between
``national'', ``regional'', and ``local'' modeling analyses. In this
context, national analyses are generally those conducted by EPA in
support of national or regional rules. Regional and local modeling
analyses are generally those conducted by the RPOs and/or States for
the purpose of developing State Implementation Plans (SIPs). EPA has
conducted national scale modeling for a variety of rules and analyses.
Additionally, the RPOs and many States are conducting regional and/or
local scale modeling of PM2.5 and regional haze across the
country. The national scale of the EPA modeling analyses requires basic
assumptions concerning local model inputs. Compared to regional or
local modeling done by the States and/or RPOs, EPA modeling may, in
some cases, use coarser grid resolution, use inventories that are not
as refined, and model performance may be highly variable from area to
area. For these reasons, national scale modeling may not always be
appropriate for local area attainment demonstrations.
Therefore, we believe that regional or local modeling conducted by
the States or RPOs is best suited as the primary modeling analysis for
a modeled
[[Page 20606]]
attainment demonstration. The local modeling is more likely to meet the
recommendations contained in EPA's modeling guidance. However, some
areas having design values close to the standard may be projected to
come into attainment within five years based on modeling analyses of
national and regional emission control measures (e.g. CAIR) that are
scheduled to occur through 2009. Regional scale modeling for national
rules such as the Tier II motor vehicle standards, the Heavy-duty
Engine standards, the Nonroad Engine standards, and CAIR indicate major
reductions in PM2.5 by 2010. A portion of these benefits
will occur in the 2006-2009 PM2.5 attainment timeframe.
Experience with past ozone attainment demonstrations has shown that
the process of performing detailed photochemical grid modeling to
develop an attainment demonstration can be very resource intensive for
States. The EPA believes that it would be appropriate for States to
leverage resources by collaborating on modeling analyses to support SIP
submittals, or by making use of recent modeling analyses that are
completed prior to the SIP submittal date. For this reason, EPA
recognizes that States may use in a PM2.5 attainment
demonstration certain local, regional and/or national modeling analyses
that have been developed to support Federal or local emission reduction
programs, provided the modeling meets the attainment modeling criteria
set forth in EPA's modeling guidance (described below). As with all
SIPs under subpart 1, the State must demonstrate that the area will
attain the PM2.5 standards as expeditiously as practicable.
The judgment of whether the modeling is appropriate for an area should
be made by the State(s) and their respective EPA regional office on a
case-by-case basis.
c. Comments and Responses
Comment: There were many commenters that agreed that States should
be able to use EPA modeling or other national or regional modeling as a
modeled attainment demonstration. One commenter recommended that the
final rule require States to show that the existing modeling
incorporates realistic assumptions, accurately reflects local emissions
and trends, and provides adequate model performance for the local
nonattainment area.
Response: We agree that national and regional modeling may be used
as part of an attainment demonstration as long as it is shown to be
applicable to the local area. This is consistent with the proposal
where we said that existing modeling should ``meet the attainment
modeling criteria set forth in EPA's modeling guidance.'' Part of the
analysis to determine if existing modeling meets the criteria in the
modeling guidance is to assess whether the modeling incorporates
realistic assumptions, accurately reflects local emissions and trends,
and provides adequate model performance for the local nonattainment area.
Comment: Some commenters thought States should be able to use EPA
modeling in the absence of an analysis of the applicability of the
modeling for a local nonattainment area. One commenter said that EPA
should determine that States should not have to do any additional
modeling analyses if the CAIR modeling showed they were expected to
attain the NAAQS by 2010.
Response: While we acknowledge there may be some circumstances in
which national or regional modeling would be appropriate to use without
local modeling and allow for such use, we disagree that national
modeling should be used in support of an attainment demonstration
without further analysis of the modeling assumptions for a particular
area. National scale modeling may not always be appropriate for local
areas. Most often, national scale EPA modeling is best suited for use
as a supplemental analysis or as part of a ``weight of evidence''
demonstration. The modeling guidance recommends supplemental analyses
for all attainment demonstrations. The guidance specifically recommends
the examination of other modeling studies as a supplemental analysis.
The EPA modeling as well as other ``non-local'' modeling can be used
for this purpose. The ``weight'' of this alternative modeling in an
attainment demonstration should be guided by how well the modeling
system is suited for the local nonattainment area. States should
consult with their EPA regional offices for further guidance and
recommendations. As such, we do not believe it to be appropriate to
determine a priori that CAIR or any other modeling analyses are
appropriate to use in a local attainment demonstration for any or all
nonattainment areas.
Comment: Several commenters believe that States should be able to
use existing EPA modeling (such as CAIR), as the basis for an extension
of the area's attainment date, if it shows that the nonattainment area
may not be able to attain the NAAQS by 2010. They believe that the
State should not have to do additional modeling to show that they need
an attainment date extension.
Response: We disagree with this comment. The CAIR modeling included
national controls that are expected to be in place by 2010 (including
the CAIR rule itself), as well as existing state and local controls
reflected in the inventory used in the CAIR analysis. It did not
include any additional local controls that could be implemented under
RACT and RACM requirements for the 1997 standards that may bring the
area into attainment sooner. Nonattainment areas are required to attain
the NAAQS as expeditiously as practicable. Therefore, updated modeling
of existing controls as well as additional local controls is needed
before an attainment date extension can be granted. Additional
information on attainment dates and extensions is contained in the
preamble to the final rule, section II.D., and additional information
on RACT and RACM requirements is contained in section II.F.
Comment: Several commenters noted an apparent inconsistency in the
language concerning who would be required to perform ``new'' local-
scale modeling. First, there are potentially conflicting statements in
the proposal when EPA states that areas with an attainment date of 2010
will need to conduct local-scale modeling to project the estimated
level of air quality improvement in accordance with EPA's modeling
guidance. This conflicts with the proposed ability for States to use
existing national or regional modeling as their modeled attainment
demonstration. Second, a portion of a sentence was removed from the
Federal Register version of the notice which differs from the pre-
Federal Register version. The published version implies that all
nonattainment areas would be required to submit new modeling.
Response: We agree that there are inconsistencies in the proposal
preamble text. To clarify, new local-scale modeling is required for
areas that are not expected to come into attainment by 2010. For other
areas, there may be national or regional modeling which may be
applicable to the area which shows they are likely to come into
attainment. As noted earlier, national scale modeling is best suited
for use as a supplemental analysis, but in some cases may be acceptable
evidence that an area will attain by 2010.
Additionally, the preamble language in the Federal Register
contained an error. A portion of a sentence was mistakenly removed,
which led to some confusion. The language in the FR notice (FR page
66008) stated ``Nonattainment areas would be required to submit an
attainment demonstration SIP that includes new modeling showing
attainment of the
[[Page 20607]]
standards as expeditiously as practicable. The new modeling will need
to include additional emissions controls or measures in order to
demonstrate attainment.'' The language should have read,
``Nonattainment areas for which local, regional, or national scale
modeling demonstrates the area will not be in attainment of the NAAQS
within 5 years of designation would be required to submit an attainment
demonstration SIP that includes new modeling showing attainment of the
standards as expeditiously as practicable. The new modeling will need
to include additional emissions controls or measures in order to
demonstrate attainment.'' This should clarify that States that cannot
show attainment within 5 years will need to develop new modeling
analyses which contain additional control strategies which show how and
when they expect to attain the PM2.5 NAAQS.
Comment: One commenter maintained that relying on large-scale
regional modeling alone may allow for PM2.5 hot spots (i.e.
small unmonitored areas projected to exceed the standard) to exist past
the attainment date.
Response: We agree that nonattainment areas with potential hotspot
issues (relatively high concentrations and/or gradients of primary
PM2.5) should not rely exclusively on regional modeling. The
EPA's attainment demonstration modeling guidance attempts to address
several aspects of hotspot issues in both monitored and unmonitored
areas \17\. The modeled attainment tests contained in EPA's modeling
guidance are primarily monitor based tests. Ambient data is combined
with the model predicted relative change in PM components to determine
if attainment of the standards is likely in the future. There are
several aspects of the attainment test. In most cases, States will run
a photochemical grid model to determine the future year predicted
PM2.5 concentrations at monitors. The modeling guidance
generally recommends that for urban scale PM2.5 modeling,
the State performs modeling analyses at 12 kilometer grid resolution or
finer. There is an additional component to the attainment test for
areas that have measured relatively high concentrations and/or
gradients of primary PM2.5 at monitors. In these cases, we
recommend running a Gaussian dispersion model for potential primary PM
sources, to determine the local impact of changes in primary PM emissions
(from the modeled sources) on predicted concentrations at the monitor(s).
---------------------------------------------------------------------------
\17\ The recommendations contained in the modeled attainment
demonstration guidance are separate from the Agency's future hot-
spot modeling guidance for transportation conformity purposes.
---------------------------------------------------------------------------
In addition, we describe an ``unmonitored area analysis'' which
uses interpolated ambient data combined with gridded model outputs to
examine whether potential violations of the NAAQS may occur in
unmonitored areas. If potential violations are indicated, we recommend
further analysis of the problem through additional local modeling.
Options for State action to address such a situation could include
imposition of reasonably available control technology to reduce
emissions, or the deployment of an air quality monitor to further
characterize the problem.
We believe that the combination of these model-based tests will
adequately determine whether attainment of the standards is likely by
the attainment date. We also believe that these tests address the issue
of hotspots by recommending a combination of photochemical modeling,
dispersion modeling of local sources, and additional monitoring and/or
emissions controls.
3. Modeling Guidance
[Section III.F.3 of November 1, 2005 proposed rule (70 FR 66008)]
a. Background
Section 110(a)(2)(K)(i) states that SIPs must contain air quality
modeling as prescribed by the Administrator for the purpose of
predicting the effect of emissions on ambient air quality. The
procedures for modeling PM2.5 as part of an attainment SIP
are contained in EPA's ``Guidance for Demonstrating Attainment of Air
Quality Goals for PM2.5 and Regional Haze.'' The proposal
summarized several of the chapters in a draft version of the modeling
guidance.
b. Final Rule
A draft of the PM2.5 attainment demonstration and
regional haze modeling guidance has now been revised (September 2006)
and is available at http://www.epa.gov/ttn/scram/guidance_sip.htm. The
draft PM2.5 attainment demonstration and regional haze
guidance has been incorporated into the ozone modeling guidance and is
now called ``Guidance on the Use of Models and Other Analyses for
Demonstrating Attainment of Air Quality Goals for the 8-Hour Ozone and
PM2.5 NAAQS and Regional Haze''. The final version of the modeling
guidance will be available at the same location in the near future.
The revised draft PM2.5 modeling guidance document is
very similar to the previous draft version, although there were several
changes and updates. Among them are new methods in treating
PM2.5 species components as part of the PM2.5
attainment test; new methods for determining potential future year
violations in unmonitored areas; new procedures for handling potential
PM2.5 ``hotspots''; and an increased reliance on
supplemental analyses, including ``weight of evidence'' analyses. The
EPA notes that the PM2.5 attainment demonstration modeling
guidance that we have released is separate from the Agency's future
hot-spot modeling guidance for transportation conformity purposes.\18\
---------------------------------------------------------------------------
\18\ In the March 10, 2006, final transportation conformity rule
(71 FR 12468), EPA committed to develop PM2.5 and
PM10 quantitative hot-spot modeling guidance for
transportation conformity determinations for highway and transit
projects of local air quality concern.
---------------------------------------------------------------------------
The modeling guidance describes how to estimate whether a control
strategy to reduce emissions of particulate matter and its precursors
will lead to attainment of the annual and 24-hour PM2.5
NAAQS. Part I of the guidance describes a ``modeled attainment test''
for the annual and 24-hour PM2.5 NAAQS. Both tests are
similar. The output of each is an estimated future design value
consistent with the respective forms of the NAAQS. If the future design
value does not exceed the concentration of PM2.5 specified
in the NAAQS, then the primary modeled test is passed. The modeled
attainment test applies to locations with monitored data.
A separate test is recommended to examine projected future year
PM2.5 concentrations in unmonitored locations.\19\
Interpolated PM2.5 ambient data, combined with modeling
data, is used to predict PM2.5 concentrations in unmonitored
areas. The goal of this analysis is to identify areas without monitors
that may be violating the PM2.5 NAAQS, often due to high
levels of primary PM2.5 (both now and in the future). The
details of the analysis are contained in the final modeling guidance.
---------------------------------------------------------------------------
\19\ Application of the unmonitored area analysis is limited to
locations which are appropriate to allow the comparison of predicted
PM2.5 concentrations to the NAAQS, based on
PM2.5 monitor siting requirements and recommendations.
---------------------------------------------------------------------------
The guidance also discusses modeling PM2.5 at monitors
where high concentrations of primary PM2.5 are measured. In
these cases, it may be beneficial to model the primary component of the
PM2.5 with a Gaussian dispersion model. Dispersion models
are better able to capture the influence
[[Page 20608]]
of primary PM sources where large concentration gradients may exist.
Grid models spread out the PM emissions to the size of the grid
(typically 4 or 12 km). This makes it difficult to judge the benefits
of control strategies that may affect primary PM sources. The final
modeling guidance recommends procedures for applying dispersion models
in these situations.
The guidance also recommends the submittal of supplemental analyses
as part of all attainment demonstrations. Supplemental analyses are
modeling, emissions, and/or ambient data analyses that are submitted as
part of a SIP, in addition to the primary modeled attainment test. The
evaluation of supplemental analyses when the predicted concentrations
in the primary attainment test are close to the NAAQS (slightly above
or slightly below) is called a weight-of-evidence (WOE) analysis. This
is simply a collection of evidence that aims to show that attainment of
the standard is likely. The final version of the modeling guidance puts
more emphasis on the submittal of supplemental analyses than in
previous versions.
Part II of the guidance describes how to apply air quality models
to generate results needed by the modeled tests for attainment. This
includes developing a conceptual description of the problem to be
addressed; developing a modeling/analysis protocol; selecting an
appropriate model to support the demonstration; selecting appropriate
meteorological episodes or time periods to model; choosing an
appropriate area to model with appropriate horizontal/vertical
resolution; generating meteorological and air quality inputs to the air
quality model; generating emissions inputs to the air quality model;
evaluating performance of the air quality model; and performing
diagnostic tests. After these steps are completed, the model is used to
simulate the effects of candidate control strategies.
Comment: Several commenters were supportive of the weight of
evidence concept. They said that PM2.5 modeling is
inherently more uncertain than previous ozone modeling and the modeling
guidance should reflect that. One commenter noted that weight of
evidence demonstrations should be ``unbiased'', meaning that States
should use all relevant analyses and not only information that helps
their case.
Response: The EPA agrees with these comments. The final modeling
guidance recommends supplemental analyses (including weight of
evidence) for all attainment demonstrations. All States should submit
modeling, ambient data, and emissions analyses in addition to the
primary modeling demonstration. A weight of evidence analysis is needed
if the predicted future year PM2.5 concentrations are
slightly higher or slightly lower than the NAAQS.
We also agree that a weight of evidence demonstration should
include all relevant information, including analyses which support
attainment and those that do not. The idea of the analysis is to
``weigh'' the evidence, both good and bad. That cannot be fairly done
if some evidence is not presented.
Comment: Several commenters suggested that a modeled attainment
demonstration should not be specifically required. Instead they suggest
that all demonstrations should be weight of evidence demonstrations.
This would include different analyses of ambient data, trends, and
modeling. But due to the uncertainties in the current PM2.5
models and emissions data, modeling would be but one part of a broader
weight of evidence approach.
Response: We disagree with this comment. Model results should be
the primary analysis of an attainment demonstration. Regardless of
current uncertainties in the PM2.5 models and emissions,
models are the only tool that can predict future concentrations of
PM2.5. The uncertainties in the model inputs and formulation
should be taken into account when evaluating the results. We agree that
a broad analysis of modeling, ambient data and emissions trends should
be part of the attainment demonstration. This is reflected in the final
modeling guidance.
4. Modeled Attainment Test
[Section III.F.4 of November 1, 2005 proposed rule (70 FR 66008)]
a. Background
The proposal described the nature of the attainment tests for the
annual average and 24-hour average PM2.5 NAAQS contained
within the modeling guidance. Both tests use monitored data to estimate
current air quality. The attainment test for a given standard is
applied at each monitor location within or near a designated
nonattainment area for that standard. There is also an additional
attainment test to be performed in unmonitored areas. Models are used
in a relative sense to estimate the response of measured air quality to
future changes in emissions. Future air quality is estimated by
multiplying current monitored values times modeled responses to changes
in emissions. Because PM2.5 is a mixture of chemical
components, the guidance recommends using current observations and
modeled responses of major components of PM2.5 to estimate
future concentrations of each component. The predicted future
concentration of PM2.5 is the sum of the predicted component
concentrations.
b. Final Rule
The nature of the PM2.5 attainment tests is unchanged.
The final modeling guidance recommends refinements to the test and
discusses the treatment of individual PM2.5 species. The
speciated modeled attainment test (SMAT) that was used to estimate
future PM2.5 concentrations for CAIR has been (mostly)
implemented in the final guidance. Among the new recommendations is to
better account for the known differences between the PM2.5
Federal Reference Method (FRM) measurements and the PM2.5
speciation measurements. For example, it is recommended to account for
the volatilization of nitrate from the FRM filters and to account for
uncertainties in organic carbon measurements by employing an ``organic
carbon by mass balance'' technique. This assumes that all remaining
mass not accounted for by other species is organic carbon mass.
Additional details are contained in the modeling guidance.
The guidance also recommends, where necessary, to spatially
interpolate PM2.5 species data to estimate the species
concentrations at FRM sites. It is necessary to estimate species
concentrations when there are no species measurements at FRM sites.
Several techniques can be used to estimate species concentrations.
Spatial interpolation techniques may be useful in many areas. In other
cases, it may be adequate to assume that data from a speciation monitor
may be representative of multiple FRM monitors. It is particularly
important to develop credible techniques to estimate species
concentrations at the locations of the highest FRM monitors.
The guidance lists several techniques that can be used. The EPA
will provide software which will apply the modeled attainment test,
using ambient data and model outputs. Additionally, the software will
interpolate the PM2.5 species data to allow application of
SMAT for all FRM monitors. The software will be available at the same
location as the final modeling guidance
(http://www.epa.gov/scram001/guidance_sip.htm).
Ultimately, it is up to the States to determine the best method to
represent the PM2.5 species concentrations, subject to EPA's
review and approval. These estimates are needed to perform the modeled
attainment test.
[[Page 20609]]
c. Comments and Responses
Comment: Several commenters were concerned that interpolation of
PM2.5 species concentrations may not be appropriate in
certain areas or situations. The concentrations can vary significantly
between urban and rural areas and even between nearby urban areas. One
commenter suggested that it might be useful to use older field study
measurements to derive current species concentrations. Another
commenter suggested that it might be reasonable to assume that
speciation measurements were representative of nearby FRM sites.
Response: We agree that interpolations of species data may not
always be the best way to estimate species concentrations at FRM sites.
The modeling guidance lists several different possible techniques.
States should review their data and situation and choose the most
reasonable methodology to estimate species concentrations.
Nonattainment areas that don't have speciation measurements at the
highest FRM site(s) need to be especially careful. The result of the
speciated attainment test can be heavily influenced by the assumed
species concentrations at the highest FRM sites. The attainment test
will be more straightforward in areas with speciation monitors at the
highest FRM sites. States are also encouraged to place speciation
monitors at the highest FRM sites. This will aid in future assessments
of attainment and ambient trends.
5. Multi-Pollutant Assessments
[Section III.F.5 of November 1, 2005 proposed rule (70 FR 66009)]
a. Background
The formation and transport of PM2.5 is in many cases
closely related to the formation of both regional haze and ozone. There
is often a positive correlation between measured ozone and secondary
particulate matter. Many of the same factors affecting concentrations
of ozone also affect concentrations of secondary particulate matter.
For example, similarities exist in sources of precursors for ozone and
secondary particulate matter. Emissions of NOX may lead to
formation of nitrates as well as ozone. Sources of VOC may be sources
or precursors for both ozone and organic particles. Presence of ozone
itself may be an important factor affecting secondary particulate
formation. The proposal recommended multi-pollutant assessments for
PM2.5 attainment demonstrations. A multi-pollutant
assessment, or one-atmosphere modeling, is conducted with a single air
quality model that is capable of simulating transport and formation of
multiple pollutants simultaneously. This type of model simulates the
formation and deposition of PM2.5, ozone, and regional haze
components, and it includes algorithms simulating gas phase chemistry,
aqueous phase chemistry, aerosol formation, and acid deposition.
b. Final Rule
The recommendation to conduct multi-pollutant assessments remains
unchanged. It is recommended to model the impacts of future year
control strategies on PM2.5, ozone, and regional haze. It
may not always be possible or convenient to do so, but it can be
beneficial to the strategy development process.
PM2.5 control strategies will have an impact on regional
haze, and will possibly impact ozone. Even if high ozone and high
PM2.5 concentrations don't typically occur during the same
time of the year, controls that affect precursors to PM2.5
may also affect ozone (e.g. NOX). The SIP submittal dates
for PM2.5, ozone, and regional haze do not currently line
up. The PM2.5 SIPs are due almost 1 year later than ozone.
But States can still do modeling analyses that can provide information
for multiple pollutants. States can use one-atmosphere models that are
capable of simulating both ozone and PM2.5. They can also
try to use consistent meteorological fields and emissions inventories
so that the same control strategies are relatively easy to evaluate for
both ozone and PM2.5. Modeling the same future year(s) for
PM2.5 and ozone can also make it easier to evaluate the
impacts of controls on both pollutants.
It should be noted that there are no specific modeling requirements
other than the recommendation to try to harmonize the ozone,
PM2.5, and regional haze analyses whenever possible.
c. Comments and Responses
Comment: One commenter suggests that multi-pollutant assessments
may not be beneficial because their area experiences winter
PM2.5 exceedances and summer ozone exceedances.
Response: We disagree with the comment. Even in situations where
high PM2.5 and ozone don't occur during the same time of
year, multi-pollutant assessments may be helpful. NOX
controls that may be needed to reduce nitrates in the winter are likely
to have an impact on ozone in the summer. As well, changes in VOCs may
have an impact on both PM2.5 and ozone. Running potential
control strategies through the same modeling platform for ozone,
PM2.5, and regional haze may allow the development of
optimized strategies.
6. Which Future Year(s) Should Be Modeled?
[Section III.F.6 of November 1, 2005 proposed rule (70 FR 66009)]
a. Background
Modeling analyses consist of base year modeling and future year
modeling. The attainment test examines the change in air quality
between the base and future years. The proposal recommended, where
possible, future modeling years should be coordinated so that a single
year can be used for both PM2.5 and ozone modeling. This
coordination will help to reduce resources expended for individual
modeling applications for PM2.5 and ozone and will
facilitate simultaneous evaluation of ozone and PM impacts.
Although there is some flexibility in choosing the future year
modeling time periods, unless the State believes it cannot attain the
standards within 5 years of the date of designation and must request an
attainment date extension, the choice of modeling years for
PM2.5 cannot go beyond the initial 5 attainment period.
Attainment date extensions will only be granted under certain
circumstances. Among other things, the State must submit an attainment
demonstration showing that attainment within 5 years of the designation
date is impracticable.
b. Final Rule
Further information is now known concerning the modeling years for
ozone. Moderate nonattainment areas are presumed to be modeling 2009.
This is consistent with the last year of the 5 year period allowed
under Subpart I for PM2.5. Therefore, it is logical to
presume that areas that are able to attain the PM2.5 NAAQS
within 5 years will model a future year of 2009. Areas that won't be
able to attain the standard in 5 years will need to request an
attainment date extension (of up to 5 additional years).
The NAAQS must be attained as expeditiously as practicable.
Therefore, attainment date extensions must contain modeling analyses to
justify the extension. Details of the required analyses are contained
in the RACT and RACM sections of the final rule. See section F for more
details.
F. Reasonably Available Control Technology and Reasonably Available
Control Measures
This section of the preamble discusses the final rule requirements
for RACT and RACM. In order to explain EPA's
[[Page 20610]]
approach in the final rule more clearly, we first discuss the statutory
and regulatory background for the RACT and RACM requirements, and we
then explain the key options and interpretations upon which we took
comment in the proposal. Thereafter, we discuss significant comments we
received on the proposal and provide brief responses to those comments.
[Additional comments and responses appear in the RTC for this final
rule located in the docket.] Most of the comments received on this
topic addressed the three options EPA proposed for the RACT
requirement, the relationship between the RACT requirement and EPA's
Clean Air Interstate Rule (CAIR), and the control measures to be
required or considered for RACT and RACM.
1. Background on Statutory Requirements for RACT and RACM
Subpart 1 of Part D of the CAA (sections 171-179B) applies to all
designated nonattainment areas. Section 172 of this subpart includes
general requirements for all attainment plans.
Notably, Congress provided EPA and States a great deal of deference
for determining what measures to include in an attainment plan.
Specifically, Section 172(c)(1) requires that each attainment plan
``provide for the implementation of all reasonably available control
measures as expeditiously as practicable (including such reductions in
emissions from existing sources in the area as may be obtained through
the adoption, at a minimum, of reasonably available control
technology), and shall provide for attainment of the national primary
ambient air quality standards.'' By including language in Section
172(c)(1) that only ``reasonably available'' measures be considered for
RACT/RACM, and that implementation of these measures need be applied
only ``as expeditiously as practicable,'' Congress clearly intended
that the RACT/RACM requirement be driven by an overall requirement that
the measure be ``reasonable.'' Thus, the rule of ``reason'' drives the
decisions on what controls to apply, what should be controlled, by when
emissions must be reduced, and finally, the rigor required in a State's
RACT/RACM analysis. For example, we previously stated that the Act
``does not require measures that are absurd, unenforceable, or
impractical'' or result in ``severely disruptive socioeconomic
impacts'' 55 FR 38327. Moreover, we interpret the term ``reasonably
available'' to allow States to consider both the costs and benefits of
applying the measure, and whether the measure can be readily and
effectively implemented without undue administrative burden. 66 FR 26969.
We also interpret the ``reasonably available control measures'' in
these provisions as referring to measures of any type that may be
applicable to a wide range of sources, whereas the parenthetical
reference to ``reasonably available control technology'' refers to
measures applicable to stationary sources. RACM can apply to mobile
sources, areas sources and stationary sources not already subject to
PM2.5 RACT requirements. Thus, RACT is a type of RACM
specifically designed for stationary sources. As noted above, States
are required to implement RACM and RACT ``as expeditiously as practicable''
as part of attainment plans designed to attain the standards.\20\
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\20\ Under the Tribal Air Rule (TAR), requirements for RACT and
RACM may be considered to be severable elements of implementation
plan requirements for Tribes.
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Section 172 does not include any specific applicability thresholds
to identify the size of sources that States and EPA must consider in
the RACT and RACM analysis. Nor, does Section 172 specifically indicate
which pollutant(s) or precursor(s) must be subject to RACM or RACT
measures to attain the NAAQS. Other pollutant-specific provisions of
the CAA do include applicability thresholds pertaining to attainment
plan requirements for NAAQS and precursor pollutants. For example,
subpart 2 of part D, which establishes additional requirements for
ozone nonattainment areas, establishes thresholds ranging from 100 to
10 tons per year for requirements applicable to ``major sources'' or
``major stationary sources,'' depending on the area's classification or
level of nonattainment. Subpart 4 of part D, which provides additional
plan requirements for PM10 nonattainment areas, establishes
thresholds of 100 and 70 tons per year for requirements applicable to a
``major source'' or ``major stationary source.''
Moreover, subpart 1, unlike subparts 2 and 4, does not identify
specific source categories for which EPA must issue control technology
documents or guidelines, or identify specific source categories for
State and EPA evaluation during attainment plan development. For ozone,
subpart 2 contains a list of specific requirements for control
techniques guidelines (CTGs) and alternative control techniques (ACT)
documents. For PM10, section 190 of the CAA (in subpart 4)
places particular emphasis on specific sources of area emissions, but
does not identify specific stationary source categories for which RACT
guidance must be issued. Section 190 requires EPA to develop RACM
guidance documents for residential wood combustion, silvacultural and
agricultural burning, and for urban fugitive dust control.
2. What Is the Overall Approach To Implementing RACT and RACM in the
Final Rule?
a. Background for RACT
Since the 1970s, EPA has interpreted RACT to mean ``the lowest
emissions limitation that a particular source is capable of meeting by
the application of control technology that is reasonably available
considering technological and economic feasibility'' as well as other
considerations.\21\ Presumptive RACT has been described as the norm
achievable by the source category.\22\
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\21\ See, 44 FR 53782, September 17, 1979, and 1976 memorandum
from Roger Strelow, Assistant Administrator for Air and Waste
Management to Regional Administrators, ``Guidance for Determining
Acceptability of SIP Regulations in Non-attainment Areas'' (Dec. 9, 1976).
\22\ See e.g. Workshop on Requirements for Non-attainment Area
Plans--Compilation of Presentations (OAQPS No. 1.2-103, revised
edition April 1978).
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Section 110 of the 1970 Clean Air Act required States to develop
SIPs providing for attainment of the NAAQS by 1975 or 1977. A number of
areas were having difficulty with developing attainment plans,
particularly for the ozone standard. In response to the implementation
needs of this time period, EPA introduced the term ``RACT'' in a 1976
memorandum from Roger Strelow, Assistant Administrator for Air and
Waste Management to Regional Administrators, ``Guidance for Determining
Acceptability of SIP Regulations in Non-attainment Areas'' (Dec. 9,
1976). In this early guidance relating to the acceptability of SIP
regulations, we indicated that our overriding concern in approving SIPs
was attaining the particular NAAQS as expeditiously as practicable
through reasonably available control technology and other reasonably
available control measures. ``The basis for fully approving state-
submitted SIP regulations continues to be demonstrated attainment and
maintenance of all national ambient air quality standards as
expeditiously as practicable,'' the memo stated.
The 1977 Clean Air Act amendments added Part D to Title I of the
Act, and for the first time the Act specifically called for EPA to
designate nonattainment areas and for SIPs to require RACT and RACM in
those nonattainment areas. In a 1979 Federal
[[Page 20611]]
Register notice, EPA noted its view that Congress adopted EPA's pre-
existing conception of RACT in the 1977 amendments. (44 FR 53782,
September 17, 1979). Also during the late 1970s, EPA developed a number
of new control techniques guideline (CTG) documents as directed in the
1977 amendments. These CTGs provided States with information on
controls for a number of categories of sources emitting VOCs, and
recommended a ``presumptive norm'' for State RACT determinations based
on the control levels achievable by sources in a given industry. CTGs
reduced the burden on States by eliminating the need for each State to
develop its own technical support for implementing the RACT
requirement. Since the CTG-recommended controls were based on general
capabilities of an industry, EPA in the 1979 guidance (44 FR 53782)
urged States in setting RACT to judge the feasibility of the
recommended controls on particular sources, and to adjust accordingly.
As noted above, EPA's early guidance related to the RACT
requirement indicated that our overriding concern in approving State
RACT requirements was attaining the particular NAAQS. We initially
required States to apply RACT to qualify for attainment extensions, and
in some cases, for plans that could not demonstrate attainment.
During the 1980s, EPA implemented the RACT requirements with a
number of CTGs and guidance documents. These materials were aimed at
addressing the attainment deadlines of 1982 and 1987 under the 1977
Clean Air Act amendments. During this time, EPA, for pollutants other
than ozone, considered RACT to be dependent upon reductions needed for
attainment as expeditiously as practicable. For ozone, where the State
performed photochemical grid modeling, the approach was the same, but
where the State used less sophisticated tools, we considered RACT to be
independent of whether the controls were needed to reach attainment as
expeditiously as practicable. We took this alternate approach because
of concerns related to the precision of modeling techniques. In other
words, in those cases, we required that a stationary source of the
requisite type and size be subject to RACT, whether or not such
controls were actually demonstrated to be necessary for the area to
attain by its specified date. (44 FR 20375-20376, April 4, 1979)
Congress followed a similar approach in the 1990 amendments to the
CAA for purposes of the ozone NAAQS in the subpart 2 provisions added
at that time. For example, section 182(b)(2) requires the imposition of
RACT controls for all VOC source categories covered by a CTG and for
all other major stationary sources of VOC located within certain
nonattainment areas. Thus, Congress required these controls without
allowing for an area-specific demonstration by the State that the area
needed the controls for attainment as expeditiously as practicable.
Extensive discussion of this requirement appeared in the 1992 general
preamble (57 FR 13541), in which EPA provided guidance for
implementation of the ozone NAAQS.
Notably, Congress did not significantly amend the generally
applicable provisions for nonattainment areas that appear in subpart 1
of Part D in 1990. This indicates that Congress intended that the
Agency retain the authority to interpret the generally applicable
nonattainment area plan requirements of section 172(c), including the
RACT and RACM requirements, in the way that is most appropriate for new
NAAQS that are subject to subpart 1. As discussed below, EPA has
determined that an approach to the RACT requirement in which RACT
varies in different nonattainment areas based on the reductions needed
for attainment as expeditiously as practicable, is appropriate for
implementation of the PM2.5 NAAQS. We believe that the
improved ability to model air quality impacts of emissions controls
allows for this approach.
b. Proposed Options for RACT
The EPA proposed and requested comment on three alternative
approaches for interpretation of the RACT requirement of section
172(c)(1) for implementation of the PM2.5 NAAQS. The EPA
proposed these approaches in order to evaluate which method would best
ensure that States consider and adopt RACT measures for stationary
sources in a way that is consistent with the overarching requirement to
attain the standards as expeditiously as practicable, while providing
flexibility for States to focus regulatory resources on those sources
of emissions that contribute most to local PM2.5 nonattainment.
Under the first proposed alternative, EPA would require States to
conduct a RACT analysis and to identify and require reasonably
available controls for all affected stationary sources in the
nonattainment area, comparable to the implementation of RACT provided
in subpart 2 governing implementation of the 1-hour ozone NAAQS. Under
this option, covered sources would be required to apply reasonable
available controls considering technical and economic feasibility, and
there would be no opportunity for States to excuse stationary sources
from control on the basis that the emissions reductions from those
controls would not be necessary to meet RFP requirements or to reach
attainment. Under this alternative, EPA proposed to limit the universe
of sources for which States must conduct a RACT analysis and impose
RACT controls, by providing an applicability threshold based upon the
amount of emissions potentially emitted by the sources. Under this
first option, EPA requested comment on a number of alternative
emissions applicability thresholds.
Under the second proposed alternative, EPA would require States to
conduct a RACT analysis and to identify reasonably available controls
for all affected stationary sources. Under this option, however, States
could thereafter determine that RACT does not include controls that
would not otherwise be necessary to meet RFP requirements or to attain
the PM2.5 NAAQS as expeditiously as practicable.\23\ Under
this approach, RACT would be determined as part of the broader RACM
analysis and identification of all measures--for stationary, mobile,
and area sources--that are technically and economically feasible, and
that would collectively contribute to advancing the attainment
date.\24\ Because RACT and RACM are considered together under this
alternative, we did not propose emissions threshold options for
evaluation of stationary source RACT. In addition, consistent with
existing policies, States would be required to evaluate the combined
effect of reasonably available measures to determine whether
application of such measures could advance the attainment date by at
least one year.\25\
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\23\ Under the Tribal Air Rule (TAR), requirements for RACT and
RACM may be considered to be severable elements of implementation
plan requirements for Tribes.
\24\ In Sierra Club v. EPA, 294 F.3d 155 (D.C. Cir. 2002), the
court stated in upholding EPA's statutory interpretation of RACM
that the Act does not compel a state to consider a measure without
regard to whether it would expedite attainment.
\25\ In this notice, where we use the shorthand phrase ``advance
the attainment date,'' it means ``advance the attainment date by one
year or more.''
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The third proposed alternative, EPA's preferred option in the
proposal, combined the first two options and is similar to the RACT
approach adopted in the final implementation rule for the 8-hour ozone
program. Under the third option, EPA would require States to conduct a
RACT analysis and to require reasonably available controls for all
affected stationary sources in
[[Page 20612]]
nonattainment areas with attainment dates more than 5 years from the
date of designation. For areas with an attainment date within 5 years
of designation (e.g. by April 5, 2010 for areas with an effective date
for designation of April 5, 2005), EPA would require RACT as under the
second proposed alternative, in which RACT would be determined as part
of the broader RACM analysis. For these areas, States could determine
that RACT does not include controls that would not otherwise be
necessary to meet RFP requirements or to attain the PM2.5
NAAQS as expeditiously as practicable. The same proposed suboptions
with respect to the size of sources for consideration under the first
alternative were also included under this alternative.
c. Proposed Approach for RACM
The EPA proposed and asked for comment on one approach for
interpreting the RACM requirement for PM2.5. The EPA based
the proposal on the approach that we adopted for other NAAQS
implementation programs. Under this approach, a State provides a
demonstration in its SIP that it adopted all reasonably available
measures needed to meet RFP requirements and to attain the standard as
expeditiously as practicable and that no reasonably available
additional measures would advance the advance the attainment date by at
least 1 year or would be necessary to meet the RFP requirement for the
area.\26\
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\26\ In the context of the PM10 NAAQS, EPA has
concluded that ``advancement of the attainment date'' should mean an
advancement of at least one calendar year. See State Implementation
Plans; General Preamble for the Implementation of Title I of the CAA
Amendments of 1990, 57 FR 12498 (April 16, 1992). See also Sierra
Club v. EPA, 294 F.3d 155 (D.C. Cir. 2002).
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Under section 172(a)(2), the state implementation plan must provide
for a nonattainment area to attain as expeditiously as practicable, but
no later than 5 years after the effective date of designation of the
area (e.g., no later than April 2010 for the final designations
effective April 2005). The statute thus creates a presumption for
attainment within 5 years of designation unless certain statutory
criteria are met for an extension of the attainment date. Under the
proposed approach to RACM for PM2.5, each State would
evaluate available measures for sources of PM2.5 or its
regulatory precursors in the area to determine if reasonable measures
were needed to meet the RFP requirement or to achieve attainment as
expeditiously as practicable. If modeling of all RACM and other state,
regional and federal measures indicates that the State will not be able
to demonstrate attainment within 5 years after designation based upon
the severity of nonattainment in that area or the availability or
feasibility of implementing controls in that area, then the State may
request an attainment date extension. We proposed that under these
circumstances, the EPA could extend the attainment date for a period of
1 to 5 years, when the State shows that it will implement all RACT and
RACM as expeditiously as practicable, has met its obligation to address
intrastate pollution transport from sources within its jurisdiction,
and still needs additional time to attain.
In the proposed rule, the EPA also took comment on the following
overall steps for implementing the statutory requirement for RACM.
(1) Identification of measures. The State would begin the process
of determining RACM by identifying all available control measures for
all sources of PM2.5 and its precursors in the nonattainment
area. The RACM can apply to mobile sources, area sources, and
stationary sources.
(2) Evaluation of measures. After the State identifies the universe
of available measures for the sources in the area, the State would
evaluate them to determine whether implementation of such measures is
technically and economically feasible, and whether the measure will
contribute to advancing the attainment date.
(3) Adoption of measures. The State would adopt all reasonably
available measures for the area consistent with meeting the applicable
RFP requirements and attaining the NAAQS as expeditiously as
practicable, in accordance with applicable policy and guidance for
attainment demonstrations. We would then approve or disapprove the
State's plan through notice and comment rulemaking. We also noted that
in reviewing the State's selection of measures for RACM, or determining
that certain measures are not RACM, EPA may independently supplement
the rationale of the State or provide an alternative reason for
reaching the same conclusion as the State.
c. Final Rule
The EPA carefully considered our interpretation of section
172(c)(1) for the PM2.5 NAAQS. Because of the variable
nature of the PM2.5 problem in different nonattainment
areas, which may require States to develop attainment plans that
address widely disparate circumstances (e.g., different source types
and mixes, different precursors and mixes of precursors, and different
meteorological conditions), we determined that the regulations
implementing the PM2.5 NAAQS should provide for a great
degree of flexibility with respect to the RACT and RACM controls.
Selected approach to RACT and RACM. The final rule reflects EPA's
decision to select option 2 for RACT and to require a combined approach
to RACT and RACM. Under this approach, RACT and RACM are those measures
that a State finds are both reasonably available and contribute to
attainment as expeditiously as practical in the specific nonattainment area.
By definition, measures that are not necessary either to meet the
RFP requirement, or to help the area attain the NAAQS as expeditiously
as practicable, are not required RACT or RACM for such area. The EPA
believes that this approach provides the greatest flexibility to a
State to tailor its SIP control strategy to the needs of a particular
PM2.5 nonattainment area, but it may require the State to
conduct a more detailed analysis to identify the most effective RACT/
RACM strategy to attain the NAAQS.
During the comment period, commenters raised concerns that this
approach may be overly burdensome on States because of the number of
potential control measures a State would need to consider. Today, we
clarify that although the State must conduct a thorough analysis of
reasonably available measures, States need not analyze every
conceivable measure, as explained in the guidance below. Instead,
``reason'' should drive States identification of potential measures,
but States should remain mindful of the public health risks of
PM2.5. As long as a State's analysis is sufficiently robust
in considering potential measures to ensure selection of all
appropriate RACT and RACM, and the State provides a reasoned
justification for its analytical approach, we will consider approving
that State's RACT/RACM strategy.
Guidance on State analysis to identify RACT, RACM and appropriate
attainment date. A State must consider RACT and RACM for all of its
nonattainment areas. However, EPA believes that if the State projects
that an area will attain the standard within 5 years of designation as
a result of existing national measures (i.e. projected to have a design
value of 14.5 or lower), then the State may conduct a limited RACT and
RACM analysis that does not involve additional air quality modeling. A
limited analysis of this type would involve the review of reasonably
available measures, the estimation of potential emissions
[[Page 20613]]
reductions, and the evaluation of the time needed to implement these
measures. If the State could not achieve significant emissions
reductions during 2008 due to time needed to implement the potential
measures or other relevant factors, then the State and EPA could
conclude that there are no further reasonably available control
measures for that area that would advance the attainment date by one
year or more relative to the presumptive outer limit for attainment
dates, i.e., 5 years from designation. In lieu of conducting air
quality modeling to assess the impact of potential RACT and RACM
measures, States may consider existing modeling information to
determine the magnitude of emissions reductions that could
significantly affect air quality and potentially result in attaining
prior to 2010 (e.g. in 2009 based on 2006-8 air quality data). If the
State, in consultation with EPA, determines from this initial, limited
RACT and RACM analysis that the area may be able to advance its
attainment date through implementation of reasonable measures, then the
State would conduct a more detailed RACT and RACM analysis, including
appropriate air quality modeling analyses, to assess whether it can
advance the attainment date.
In general, the combined approach to RACT and RACM in the final
rule includes the following steps: (1) Identification of potential
measures that are reasonable; (2) modeling to identify the attainment
date that is as expeditious as practicable; and (3) selection of RACT
and RACM.
Identification of potential measures. The State's review of
potential measures must be sufficient to identify all appropriate RACT
and RACM. As stated previously, inherent to RACT/RACM is the basic
requirement that the measure be ``reasonable.'' A State need not
evaluate measures in its RACM/RACT analysis that it determines are
unreasonable such as measures that are ``absurd, unenforceable, or
impractical'' or that would cause ``severely disruptive socioeconomic
impacts, (e.g. gas rationing and mandatory source shutdowns); such
measures are not required by the Act. 55 FR 38327.
As we also stated earlier, a State's RACT/RACM analysis not only
involves an assessment about what emissions sources to control and to
what level, but also a judgment as to when it is reasonable to require
a sector to comply with a given measure. Accordingly, if the State or
Federal rules already heavily regulate a given sector, it is reasonable
for the State to first look to unregulated parts of the sector for
RACT/RACM measures, especially, in light of costs already realized by
the regulated sector. A State may conclude that it is unreasonable to
further regulate the industry, or that it is only reasonable to impose
measures in the latter years of the attainment plan.
Finally, the State should use reason in the extent of its efforts
to identify potential control measures. For example, if a review of
monitoring data and modeling studies indicates that reductions in
SO2 are much more effective in reducing ambient
PM2.5 than reductions in other pollutants, we expect that
the State will more vigorously identify RACT/RACM measures for
SO2 than for other pollutants. Conversely, if reductions in
a given pollutant, even in large quantities, would have trivial impacts
on PM2.5, less rigor is needed in the State's assessment of
controls for that pollutant, because such controls could not contribute
to advancing the attainment date. Likewise, where reducing emissions of
a pollutant is effective in reducing ambient PM2.5, if the
emissions inventory for that pollutant is dominated by a given type of
emissions source, then it would be appropriate to focus the analysis on
measures for that segment of the inventory. No RACT/RACM analysis is
needed for pollutants that are not attainment plan precursors for a
particular PM2.5 nonattainment area.
As supporting information for identification of RACT and RACM, the
State ordinarily provides data on technologically feasible control
measures:
--A list of all emissions source categories, sources and activities in
the nonattainment area (for multi-State nonattainment areas, this would
include source categories, sources and activities from all states which
make up the area)
--For each source category, source, or activity, an inventory of direct
PM2.5 and precursor emissions;
--For each source category, source, or activity, a list of technologically
feasible emission control technologies and/or measures \27\
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\27\ The EPA believes that it is not necessary to identify every
possible variation of every type of control measure, or all possible
combinations of technologies and measures that would apply to a
given source or activity if the State has properly characterized the
potentially available emissions reductions and their costs. For
example, EPA believes that the State can conduct a thorough analysis
of VMT reduction measures without including every possible level or
stringency of implementation of certain possible measures or
combinations of measures for reducing VMT, so long as those measures
would not affect the overall assessment of VMT reduction
capabilities and the associated costs.
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--For each technologically feasible emission control technology or
measure, the State should provide the following information: (1) The
control efficiency by pollutant; (2) the possible emission reductions
by pollutant; (3) the estimated cost per ton of pollutant reduced; and
(4) the date by which the technology or measure could be reasonably
implemented.
Based on this and other relevant information, the State will
identify the reasonable measures (potential RACT and RACM) to be
included in air quality modeling. (At its option, the State may prefer
not to make a judgment on whether certain measures are technically and
economically feasible, if it believes they will not contribute to
earlier attainment. In that case, the State could include those
measures in the modeling, and later exclude them from RACT and RACM by
showing that all the excluded measures together would not advance the
attainment date by at least 1 year.) As previously mentioned, in
determining the attainment date that is as expeditious as practicable,
the State should consider impacts on the nonattainment area of
intrastate transport of pollution from sources within its jurisdiction,
and potential reasonable measures to reduce emissions from those sources.
Modeling to determine the attainment date that is as expeditious as
practicable. Second, for purposes of determining the attainment date
that is as expeditious as practicable, the State will need to conduct
modeling to show the combined air quality impact of all of the
potential measures identified in the first step with a modeling
analysis for the year 2009. A base case scenario for the year 2009
would project future air quality given implementation of existing
measures (Federal, State and local). If this base case scenario
demonstrates attainment by 2010, then the State must demonstrate why
attainment could not be achieved in an earlier year. (As noted above,
given the April 2008 due date for SIP submissions, it may be difficult
to achieve earlier attainment in many cases).
If the base case scenario does not demonstrate attainment, then a
control case scenario (described below) is needed to examine whether
the reasonable, technically and economically feasible measures
identified by the State would result in attainment in 2009. The control
case scenario would add potential SIP measures--e.g. potential RACT/
RACM, plus any candidate intrastate transport measures that the State
has identified
[[Page 20614]]
and would be feasible to implement by that year. States in multi-State
nonattainment areas are strongly encouraged to collaborate on their
modeling analyses. This modeling, along with other information known as
weight of evidence considerations, would inform a judgment as to
whether reasonable measures could lead to attainment of the standards
within 5 years after designation. If the analysis does not demonstrate
attainment by April 2010 (2009 analysis year), then the analysis would
serve as the technical basis for the State to seek an extension of the
attainment date for that area. Further analysis would then be necessary
and is required to identify the specific attainment date.
The choice of future years to model beyond 2010 may vary from area
to area. Often, modeling potential controls in two different future
years may be necessary to support a judgment that a projected
attainment year is as expeditious as practicable. If the area is
projected to remain over the standard in the early projection year
(e.g., 2009) despite the emission reductions from the modeled control
measures, but is projected to be well below the standard in the later
projection year (e.g., 2012), interpolation and emission inventory
analysis could identify an intermediate year as the appropriate
attainment date. There may be cases in which modeling a single year is
sufficient because modeling of all technically and economically
feasible controls results in attainment by a narrow margin in that year.
For many areas, EPA modeling analysis for CAIR and other modeling
analyses that have been performed suggest a number of nonattainment
areas will have a modest amount (in some cases only a few tenths of a
microgram) of needed reductions in ambient levels after 2010 to reach
attainment. For any such area, and for areas otherwise expected to
attain relatively soon after 2010 (for example, due to substantial
reductions in a dominant local source), EPA believes that this analysis
should be for a year no later than 2012. A later date (e.g., 2014) may
be appropriate for areas with very high PM2.5 levels that
face difficulty attaining within 10 years.
The EPA believes that it is not reasonable to require States to
model each and every year between 2009 and 2014 to determine the
appropriate attainment date. Modeling future year inventories is a time
consuming and resource intensive process. Multiple models and pre-
processors are needed in order to generate year specific emissions for
the various emissions sectors (e.g. mobile, non-road, non-EGU point,
EGU point, etc.). Because it is not reasonable to model every year, a
logical choice often may be to model a year in the middle of the
period. As such, we recommend modeling an emissions year no later than
2012 as the initial extension date (which translates to a 2013
attainment date). If this modeling indicates that the area can reach
attainment by 2012, then the State can further analyze emissions and
strategies to determine if the attainment date can be advanced to an
earlier year. If the modeling indicates that the area cannot reach
attainment by 2012, then the modeling will serve as further
justification for granting a longer attainment date extension (e.g.,
attainment date of 2015 with modeling for 2014). In that case,
additional modeling of 2014 with further emissions controls would be
required in order to show attainment. Again, the State should then
further analyze emissions and strategies to determine if the attainment
date can be advanced to an earlier year between 2012 and 2015.
Additionally, in the discussion of air quality modeling issues in
section II.E above, we discuss the benefits of addressing control
strategies for multiple pollutants. Part of the challenge of multi-
pollutant modeling is coordinating the future modeling years for
different pollutants in order to minimize the number of required future
year model runs. As part of the requirements of the 8-hour ozone
implementation rule, States are currently working on modeling analyses
for 2009 and in some cases for 2012 (serious nonattainment areas). For
an area that cannot attain the PM2.5 NAAQS by 2010, this may
be reason to select 2012 as the year to model, so that the State could
conduct the modeling for both ozone and PM2.5 in tandem.
This would, in some cases, allow the pooling of resources (e.g.,
inventories, model runs, etc.) and provide for faster development of a
PM2.5 attainment demonstration.
It may also be possible for the State to look at 2009 and 2014
only. In this instance, the State may find sufficient data to
interpolate results for the years in between based on estimated changes
in emissions.
We emphasize that when a State models later years, that this
analysis must take into account potential controls that the State may
have determined would not be RACT or RACM for an earlier year. For
example, some measures that are impractical to implement by 2009 could
be reasonable if implemented by 2010, 2011 or 2012. Thus, when the
State models later years, the list of potential controls should be
expanded to include technically and economically feasible measures that
can be implemented by the analysis year.
Selection of RACT & RACM. Based on this analysis, the State should
make decisions on RACT, RACM, intrastate measures, and the attainment
date that is as expeditious as practicable. Because EPA is defining
RACT and RACM as only those reasonable, technically and economically
feasible measures that are necessary for attainment as expeditiously as
practicable, the State need not adopt all feasible, reasonable
measures. The State may exclude those reasonable measures that,
considered collectively, would not advance the attainment date.
Comments and Responses
Comment: A number of commenters generally supported EPA's second
proposed alternative to RACT (option 2). Most of these commenters
expressed concern that the other options would require the imposition
of controls whether or not they were needed to attain the
PM2.5 standards as expeditiously as practicable. Some State
and local commenters also urged EPA to select option 2 as the best
interpretation of the RACT requirement for PM2.5 because
they believe that it will be the most appropriate approach for
designing attainment strategies for their particular nonattainment area
or areas.
Response: The EPA agrees that these two points are important
considerations. After carefully considering the options, we concluded
that Option 2 was the most suitable approach for the PM2.5
NAAQS. Options 1 and 3 do not reduce the States' burden to analyze
potential control measures as the States would still be required to
look beyond the mandated RACT for reasonably available control measures
(RACM). Moreover, Options 1 and 3 could require imposition of controls
on some sources that would not strictly be necessary to attain the
NAAQS as expeditiously as practicable. Given the nature of the
PM2.5 nonattainment problem, EPA concluded that an
interpretation that provides the maximum flexibility is a better approach.
Comment: Some commenters recommended that EPA modify proposed
option 2 to include a tons-per-year threshold. Under such an approach,
the States and EPA would only require RACT for sources whose emissions
were above the threshold. Most of these comments recommended a RACT
threshold of 100 tons per year. These commenters expressed concern that
if option 2 were implemented
[[Page 20615]]
without such a threshold, States would be burdened with conducting RACT
analyses for very small sources or source categories with low emissions.
Response: The EPA believes that under the approach chosen for the
final rule in which RACT is considered to be a part of the overall RACM
process, it would be difficult to define a threshold that would apply
for all types of sources and for all types of control measures in all
nonattainment areas. It has not been common practice under past EPA
policy to establish or use an emissions threshold when considering
sources for possible emission reductions as part of a RACM analysis to
show attainment as expeditiously as practicable. Indeed, many of the
control technique guidelines for VOC RACT do not recommend an emissions
threshold. A state needing significant emission reductions to attain
the standards in a given area even by 2015 would likely conclude that
controls should be considered on smaller sources. In contrast, a State
with an area that exceeds the standard by only a few tenths of a
microgram per cubic meter may not need to consider controls on smaller
source to reach attainment as expeditiously as practicable. The EPA has
selected option 2 for interpretation of the RACT requirement for
PM2.5, in part, specifically because that approach
contemplates that States will conduct an appropriate analysis of the
spectrum of source categories and potential controls available. To cut
off such analysis at a set emissions-based cut point for all sources
and all areas would undermine one of the key benefits of the approach.
Accordingly, EPA disagrees with comments that option 2 should include a
nationally-defined threshold for the size of sources or source
categories that require RACT analyses.
Comment: A number of commenters supported EPA's first and third
proposed alternative approaches to RACT (option 1 and option 3).
Commenters supporting these two options used similar reasoning.
Commenters cited the statutory language in section 172(c)(1) requiring
that the attainment plan provide for ``at a minimum'' the adoption of
RACT. Accordingly, these commenters argued that RACT is an independent,
minimum requirement of attainment plans irrespective of the attainment
demonstration and that option 2, which would not require the adoption
of RACT for all sources, has no policy or legal justification. Other
commenters noted that option 1 would be much easier to implement,
because RACT would be defined according to technical reasonableness and
would not hinge on complicated determinations involving attainment
demonstrations. Some commenters argued that option 1 provides for
greater equity, because similar measures would be required for similar
sources for all nonattainment areas. Finally, some commenters believed
that it is inherently inconsistent to assert that plans have met the
requirement for attainment ``as expeditiously as practicable'' without
applying RACT to all major sources.
Response: The EPA disagrees with these comments. The EPA believes
that option 2 is fully consistent with section 172(c)(1). Section
172(c)(1) requires that attainment plans must provide for the
implementation of RACM as expeditiously as practicable (including such
reductions in emissions from existing sources in the area as may be
obtained through the adoption, at a minimum, of RACT). Contrary to the
commenters' assertions, this language does not demonstrate that RACT is
required for all sources, independent of RACM and attainment
demonstrations. Moreover, this provision does not require RACT whether
or not imposition of technology would advance the attainment date.
Instead, section 172(c)(1) explicitly provides that RACT is included
within the definition of RACM, and EPA has previously determined that
the CAA only requires such RACM as will provide for attainment as
expeditiously as practicable. (See 57 FR 13498, 13560). The courts have
deferred to this interpretation and concluded that EPA interprets RACM
as a collection of reasonable measures that would advance the
attainment date. See Sierra Club v. EPA, 294 F.3d 155, 162 (D.C. Cir.
2002); see also Sierra Club v. EPA, 314 F.3d 735, 744 (5th Cir. 2002).
The CAA does not ``compel [ ] a State to consider whether any measure
is `reasonably available' without regard to whether it would expedite
attainment in the relevant area.'' Sierra Club v. EPA, 294 F.3d at 162.
The EPA concludes that because section 172(c)(1) establishes that RACT
is a part of RACM, EPA is reasonably applying the same interpretation
to the RACT requirement for PM2.5. The RACT is a part of the
collection of measures that are necessary to reach attainment as
expeditiously as practicable. It is thus directly related to what a
specific area needs to attain the NAAQS, and States need not implement
reasonably available measures that would not advance the attainment
date as part of the PM2.5 RACT requirement.
The EPA also finds that option 2 is consistent with the statutory
language providing that a State must apply RACT to existing sources,
``at a minimum,'' to meet its requirement to apply RACM. We interpret
the ``at a minimum'' clause to mean that when a State determines that
control of a specified existing stationary source(s) is necessary to
attain, the State must apply RACT to that source. Further, EPA believes
this requirement for RACT applies to stationary sources as a group, and
not to each stationary source.
The EPA finds sound policy reasons for choosing option 2. While an
approach that provided for application of the same controls in all
areas would provide for more equity across areas, EPA emphasizes that
equity is only one of many factors considered by EPA when deciding
between options 1, 2 and 3. The EPA believes that it is also important
to ensure that control strategies focus on the most effective measures
with the greatest possibility for significant air quality improvements.
In addition, while EPA agrees that options 1 and 3 could provide for
greater ease of implementation, this is also only one of the factors
EPA considered when deciding between the proposed options. Under option
2, States have a greater burden and responsibility to identify the
local strategy that is tailored to their particular air quality
problem. At the same time, the States have the ability to identify the
sources with the greatest impact on nonattainment and to identify a
sound strategy that achieves attainment in the most sensible manner.
The EPA believes that approaching RACT and RACM in this manner is
consistent with the overall philosophy imbedded in the SIP program
since its inception in the late 1960s and early 1970s.
Comment: Some commenters believed that the proposed RACM
requirement was too broad. These commenters believed that the
requirement to analyze the entire ``universe'' of possible measures was
too burdensome for States. Commenters felt this was especially true in
light of the lack of federally issued CTG and ACT documents for
PM2.5 and its precursors for all potential source categories.
Response: As explained earlier, States should apply ``reason'' in
identifying measures to evaluate as potential RACM/RACT. We recognize
that States are implementing the PM2.5 standard for the
first time, and do not have the long history and experience in
implementing PM2.5 as they have in implementing the
PM10 and ozone standards. Accordingly, we expect that both
the States and EPA will expend extra effort in developing and
evaluating attainment plans that contain appropriate controls. A number
[[Page 20616]]
of resources exist to provide States with information on potential
control measure costs and emissions reductions. We intend to facilitate
the sharing of information through a control measure website and other
efforts, and expect that States will develop screening methods to
reduce the burden of analysis.
Comment: One commenter asserted that EPA should not require the
analysis for, or implementation of, RACT and RACM for sources
throughout the entire nonattainment area, and should permit States to
focus only on sources located in smaller specific ``problem areas''
within the nonattainment area.
Response: The EPA designated areas nonattainment based upon
analysis of the geographic area with sources that ``contribute'' to the
violation of the NAAQS in the area, in accordance with section 107(d).
These designations are based upon, among other things, a network of
monitors that the State and EPA previously agreed represented the
ambient air concentrations throughout the area. Additional analysis of
information during the designation process indicated those areas that
contributed to the violations at the violating monitor because of,
among other things, the amount of emissions in such adjoining areas.
Accordingly, the State in which a nonattainment area is located must
evaluate the full range of sources of PM2.5 and its
precursors throughout the designated nonattainment area during the
development of the SIP. The EPA agrees that there are some
nonattainment areas where one or a few large emissions sources may be
causing localized concentrations at a monitor that are much higher than
those within the remainder of the nonattainment area. For such areas,
the nonattainment strategy will likely not succeed without addressing
those sources. The EPA does not, however, believe it is acceptable that
the nonattainment strategy focus only on those sources, because
additional reductions within the nonattainment area would still have
the potential to advance the attainment date. Exempting portions of the
nonattainment area could expose a portion of the public residing
downwind in the area to exposure to levels of PM2.5 that
exceed the NAAQS for longer than necessary, and the health detriments
from such exposure, merely to minimize the impact of having to impose
control strategies on sources upwind. Moreover, to the extent that
monitoring in one portion of a nonattainment area indicates violations
in multiple portions of the area, a strategy that solely focused upon
the sources in the immediate vicinity of the monitor might fail to
assure that the NAAQS is achieved throughout the area. Because NAAQS
violations generally reflect a combination of regional scale,
metropolitan scale, and local scale impacts, and all three scales must
be addressed, EPA requires RACT/RACM submittals to address sources
throughout the nonattainment area.
Comment: Some commenters agreed with EPA's view that State's RACM
analysis must address those measures that a State declines to adopt and
must show whether the combined measures would cumulatively advance the
attainment date by at least 1 year. One commenter questioned the legal
basis for EPA's determination that the only controls necessary to
attain the PM2.5 NAAQS as expeditiously as practicable are
those that would cumulatively advance an area's projected attainment
date by at least one calendar year. The commenter suggested that
control measures that would advance attainment by a smaller increment
``would meet the criteria endorsed in Sierra Club [Sierra Club v. EPA,
294 F.3d 155 (D.C. Cir 2002)] by `expedit[ing] attainment in the
relevant area.' ''
Response: The EPA has consistently interpreted RACM as a collection
of measures that would advance the attainment date by at least 1 year,
and the courts have determined that the statutory RACM requirement is
ambiguous and deferred to EPA's interpretation of the requirement. See
Sierra Club v. EPA, 314 F.3d 735, 744 (5th Cir. 2002); see also Sierra
Club v. EPA, 294 F.3d, 155 162 (D.C. Cir. 2002). Contrary to the
commenter's suggestion, the court in Sierra Club v. EPA, did not
endorse specific criteria for identifying control measures that
expedite attainment, but instead deferred to EPA's interpretation of an
ambiguous statutory term. The courts deferred to EPA's interpretation
after reviewing EPA's approval of State SIP submissions. The EPA
conducts such reviews consistent with its determination that the CAA
only requires such RACM as will provide for attainment as expeditiously
as practicable, and its belief that it would be unreasonable to require
implementation of measures that would not in fact advance attainment.
See 57 FR 13498, 13560 (April 15, 1992); see also 44 FR 20372, 20374
(April 4, 1979). In considering whether a collection of measures would
advance the attainment date of an area, EPA has previously interpreted
the phrase ``advance the attainment date'' as meaning that the
attainment date would be advanced by at least 1 year. See e.g., 66 FR
57160, 57182 (Nov. 14, 2001) (approval of Houston SIP); 66 FR 586 (Jan
3. 2001) (approval of DC area SIP). Further, EPA's use of a one-year
increment in determining whether a collection of measures would advance
the attainment date is reasonable and consistent with the fact that all
areas will be designing attainment demonstrations for the annual
PM2.5 standard. Section 172(a)(2)(C) statute uses 1 year as
the increment by which attainment date extensions can be granted. Thus,
requiring evaluation of whether control measures would advance
attainment by an increment of 1 year is a reasonable approach for the
PM2.5 NAAQS.
Comment: Some commenters recommended that EPA consider not
requiring a RACM analysis for areas projected to attain the standards
within 5 years of designation, i.e., by April 2010 for the areas
currently designated nonattainment. One commenter suggested that
practical considerations would make it impossible for any State
projected to attain by 2010 to advance the attainment date by a year.
This commenter noted that because measures to provide for attainment by
2010 must be implemented by the beginning of 2009, and SIPs are not
submitted until April 2008, it would impossible to advance the
implementation of measures by 1 year (that is, the beginning of 2008).
Response: The EPA generally agrees that given the time constraints
it will be difficult for States with areas currently designated
nonattainment to devise, adopt, and implement RACM measures to advance
the attainment date before 2010. At the same time, however, we note
that nothing precludes States from taking early action and we encourage
States to take actions to reduce PM2.5 concentrations where
feasible even before the SIPs are submitted. RACM is required by the
CAA and thus EPA cannot waive the requirement for the analysis. At the
same time, EPA recognizes that a streamlined analysis may be
appropriate given the short time periods involved.
3. Observations and Considerations in Determining RACT and RACM
a. Background
The preamble to the proposed rule included a discussion of general
considerations for RACT (70 FR 66020 and 66021, latter part of section
III.I.6) and RACM (70 FR 66028, section III.1.15). The preamble to the
final rule retains this discussion with some modifications and
restructuring to
[[Page 20617]]
reflect the combined approach to RACT and RACM
b. Final Rule
General considerations. Once the State has identified measures and
technologies that are available for implementation in the nonattainment
area, then it must evaluate those measures to determine whether
implementation of such measures are reasonable, and would collectively
advance attainment. Many of the factors that the State should take into
consideration in determining whether a measure is ``reasonable'' are
related to the measure's technical and economic feasibility. Since RACM
applies to area and mobile sources as well as stationary sources, the
State should consider other factors as well in conducting its RACM
analysis. For example, in many cases obtaining emissions reductions
from area and mobile sources is achieved not by adding control
technology to a specific emissions source, but by reducing the level of
activity of a fleet of vehicles or by modifying a type of commercial
process. In these situations, the State should also consider local
circumstances such as infrastructure, population, or workforce and the
time needed to implement the measure in light of the attainment date.
The EPA believes that while areas projected to attain within 5
years of designation as a result of existing national measures should
still be required to conduct a RACT and RACM analysis, such areas may
be able to conduct a limited RACT and RACM analysis that does not
involve additional air quality modeling. A limited analysis of this
type could involve the review of available reasonable measures, the
estimation of potential emissions reductions, and the evaluation of the
time needed to implement these measures. If the State could not achieve
significant emissions reductions by the beginning of 2008 due to time
needed to implement reasonable measures or other factors, then it could
be concluded that reasonably available local measures would not advance
the attainment date. In lieu of conducting air quality modeling to
assess the impact of potential RACT and RACM measures, existing
modeling information could be considered in determining the magnitude
of emissions reductions that could significantly affect air quality and
potentially result in earlier attainment. If the State, in consultation
with EPA, determines from this initial, more limited RACT and RACM
analysis that the area may be able to advance its attainment date
through implementation of reasonable measures, then the State would
conduct a more detailed RACT and RACM analysis.
Observations on control opportunities. The implementation of the
PM2.5 NAAQS is in its initial stages, and many of the
designated PM2.5 nonattainment areas are not current or
former PM10 nonattainment areas. Thus, some existing
stationary sources in these areas may currently be uncontrolled or
undercontrolled for PM2.5 or PM2.5 precursors.
Further, to this point in time, emissions controls for existing sources
in these areas may have focused primarily on particulate matter that is
filterable at stack temperatures and thus may not adequately control
condensable emissions. In addition, States should bear in mind that the
controlled sources may have installed emission controls 15 years ago or
more, and there may now be cost-effective opportunities available to
reduce emissions further through more comprehensive and improved
emissions control technologies, or through production process changes
that are inherently lower in emissions.
Moreover, improved monitoring methods may enhance the ability of
sources to maintain the effectiveness of installed emissions controls
and to reduce emissions by detecting equipment failures more quickly.
For example, State imposition of requirements for more frequent
monitoring (e.g., continuous opacity monitors, PM continuous emissions
monitors, etc.) may provide greater assurance of source compliance and
quicker correction of inadvertent upset emissions conditions than
existing approaches.
Even in former or current PM10 nonattainment areas,
existing requirements for controlling direct PM emissions (e.g., with a
baghouse or electrostatic precipitator) may not have been revised
significantly since the 1970's. When EPA established the
PM10 standards in 1987, we stated in the preamble that it
was reasonable to assume that control technology that represented RACT
and RACM for total suspended particulates (TSP) should satisfy the
requirement for RACT and RACM for PM10. 52 FR 24672 (July 1,
1987). The basis for EPA's belief was that controls for PM10
and TSP would both focus on reducing coarse particulate matter, and
specifically that fraction of particulate matter that is solid (rather
than gaseous or condensable) at typical stack temperatures. However,
emission controls to capture coarse particles in some cases may be less
effective in controlling PM2.5. For this reason, there may
be significant opportunities for sources to upgrade existing control
technologies \28\ and compliance monitoring methods to address direct
PM emissions contributing to fine particulate matter levels with
technologies that have advanced significantly over the past 15 years.
---------------------------------------------------------------------------
\28\ For example, see past EPA guidance on PM2.5
control technologies: Stationary Source Control Techniques Document
for Fine Particulate Matter (EPA-452/R-97-001), EPA Office of Air
Quality Planning and Standards, October 1998.
---------------------------------------------------------------------------
Precursor Controls. It will be important for States to conduct RACT
and RACM determinations for stationary sources of PM2.5
precursors as well as direct PM2.5 emissions although, as
noted above, the known atmospheric chemistry of the area may dictate
the necessary rigor of this analysis. A significant fraction of
PM2.5 mass in most areas violating the standards is
attributed to secondarily-formed components such as sulfate, nitrate,
and some organic PM, and EPA believes that certain stationary sources
of precursors of these components in nonattainment areas currently may
be poorly controlled. Accordingly, to address these precursors, States
should review existing sources for emission controls or process changes
that could be reasonably implemented to reduce emissions from activities
such as fuel combustion, industrial processes, and solvent usage.
Multi-State Nonattainment Areas. States in multi-State
nonattainment areas will need to consult with each other on appropriate
level of RACT and RACM for that area. We anticipate that States may
decide upon RACT and RACM controls that differ from State to State,
based upon the State's determination of the most effective strategies
given the relevant mixture of sources and potential controls in the
relevant nonattainment areas. So long as each State can adequately
demonstrate that its chosen RACT and RACM approach will provide for
meeting RFP requirements and for attainment of the NAAQS as
expeditiously as practicable for the nonattainment area at issue, we
anticipate approving plans that may elect to control a somewhat
different mix of sources or to implement somewhat different controls as
RACT and RACM. Nevertheless, States should consider RACT and RACM
measures developed for other areas or other States. EPA may consider
such measures in assessing the approvability of a State's SIP.
c. Comments and Responses
Comment: In the proposed rule, EPA indicated that States could
consider the ``social acceptability'' of measures as a
[[Page 20618]]
factor in the determination of what constitutes RACM in a given area. A
number of commenters recommended that EPA eliminate use of this factor.
Some commenters questioned whether States or EPA had the legal
authority to exclude measures from consideration based on social
acceptability or popularity, if the measures are technically and
economically available, and are needed to attain the NAAQS for
protection of public health. Others expressed concerns that inclusion
of such a factor would inevitably result in the elimination of controls
for area and mobile sources and for this reason would unfairly focus
emissions reduction strategies on industrial sources of
PM2.5 and precursors.
Response: The EPA believes that in developing RACM measures, it is
important that States not rely unduly on measures that would be very
difficult to enforce in practice. We discourage States from relying on
measures that on paper may seem reasonably available but in practice
might fail to achieve benefits due to the problems and costs of
effectively enforcing these measures. However, we recognize that the
CAA does not identify ``social acceptability'' as a factor in the
definition of what may constitute RACT or RACM, and more generally the
CAA does not establish a preference for measures that affect industrial
sources instead of the general public and are therefore more likely to
be ``socially acceptable.'' Therefore, given the concerns raised by
commenters that establishment of ``social acceptability'' as a factor
in the RACM analysis is without basis in the CAA and might result in
inappropriate skewing of control strategies, we have removed this term
from the final rule. We reiterate, however, that capability of
effective implementation and enforcement are relevant considerations in
the RACM analysis, even though public ``unpopularity'' is not.
Moreover, in assessing the efficacy of measures and the credit they
should be given in the context of attainment demonstrations or RFP
calculations, EPA believes that such considerations are important.
4. What Factors Should States Consider in Determining Whether an
Available Control Technology or Measure Is Technically Feasible?
a. Background
The following provides guidance for States to consider in
determining whether an available control technology is technologically
feasible.
b. Final Rule
The technological feasibility of applying an emission reduction
method to a particular source should consider factors such as the
source's process and operating procedures, raw materials, physical
plant layout, and any other environmental impacts such as water
pollution, waste disposal, and energy requirements. For example, the
process, operating procedures, and raw materials used by a source can
affect the feasibility of implementing process changes that reduce
emissions and the selection of add-on emission control equipment. The
operation and longevity of control equipment can be significantly
influenced by the raw materials used and the process to which it is
applied. The feasibility of modifying processes or applying control
equipment also can be influenced by the physical layout of the
particular plant. The space available in which to implement such
changes may limit the choices and will also affect the costs of control.
Reducing air emissions may not justify adversely affecting other
resources by increasing pollution in bodies of water, creating
additional solid waste disposal problems or creating excessive energy
demands. An otherwise available control technology may not be
reasonable if these other environmental impacts cannot reasonably be
mitigated. For analytic purposes, a State may consider a
PM2.5 control measure technologically infeasible if,
considering the availability (and cost) of mitigating adverse impacts
of that control on other pollution media, the control would not, in the
State's reasoned judgment, provide a net benefit to public health and
the environment. However, in many past situations, States and owners of
existing sources have adopted PM2.5 control technologies
with known energy penalties and some adverse effects on other media,
based on the reasoned judgment that installation of such technology
would result in a net benefit to public health and the environment.
States should consider this in determining technical feasibility. The
costs of preventing adverse water, solid waste and energy impacts
should be included in assessing the economic feasibility of the
PM2.5 control technology.
One particular cross-media issue relates to concentrated animal
feeding operations (CAFOs). Should a State determine that reductions of
direct PM2.5 or PM2.5 precursors from CAFOs are
necessary for attainment in a nonattainment area, EPA strongly suggests
that the State address these reductions from a cross-media perspective.
Since 2003, EPA and many stakeholders have been interested in
developing a framework to enable CAFOs to pursue superior environmental
performance across all media. We are aware that today some CAFOs
voluntarily conduct whole-farm audits to evaluate releases of
pollutants to all media through Environmental Management Systems, self-
assessment tools, performance track, ISO 14001 certification, and
State-approved trade offs in meeting regulatory thresholds between air
and water that accomplish the best overall level of environmental
protection given State and local conditions. The EPA continues to
believe the development of new and emerging technologies offers the
potential to achieve equivalent or greater pollutant reductions than
achieved solely by effluent guidelines and standards. Many of these are
superior from a multimedia perspective, and EPA would like to encourage
superior multimedia solutions. SIPs which need to address ammonia may
provide a unique opportunity to encourage multimedia approaches at
CAFOs. For example, the addition of animal by-products provides a
valuable source of nutrients for crops, improves soil structure which
enhances soil permeability, and adds valuable organic matter that
improves soil health. However, inappropriate application can lead to
air and water quality concerns or the improvement of one media at the
cost of another. Optimal application technologies and rates reduce
potential air and water quality standards violations. The EPA does not
want to discourage approaches that are superior from a cross media
perspective.
The EPA recommends that States evaluate alternative approaches to
reducing emissions of particulate matter by reviewing existing EPA
guidance \29\ and other sources of control technology information. The
EPA's 1998 guidance presents information on topics such as the design,
operation and maintenance of general particulate matter control systems
such as electrostatic precipitators, fabric filters, and wet scrubbers.
The filterable particulate matter collection efficiency of each system
is discussed as a function of particle size. The guidance document also
provides information concerning
[[Page 20619]]
other relevant considerations such as energy and environmental
considerations, procedures for estimating costs of particulate matter
control equipment, and evaluation of secondary environmental impacts.
Because control technologies and monitoring approaches are constantly
being improved, the State should also consider more updated or advanced
technologies not referenced in this 1998 guidance when conducting a
RACT determination. Emissions reductions may also be achieved through
the application of monitoring and maintenance programs that use
critical process and control parameters to verify that emission
controls are operated and maintained so that they more continuously
achieve the level of control that they were designed to achieve.\30\
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\29\ Stationary Source Control Techniques Document for Fine
Particulate Matter (EPA-452/R-97-001), EPA Office of Air Quality
Planning and Standards, October 1998. See also: Controlling
SO2 Emissions: A Review of Technologies (EPA/600/R-00/
093), EPA Office of Research and Development, November 2000.
\30\ See EPA's Web site for more information:
http://www.epa.gov/ttn/emc/monitor.html.
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c. Comments and Responses
Comment: One commenter noted that the guidance for ``technical
feasibility'' implies that States look at individual sources with a
BACT-like case-by-case analysis. The commenter recommended that source
owners conduct such a site-specific analysis and submit the analysis to
the State through the permitting process.
Response: While the analytical analysis to identify RACT is similar
to BACT, as noted above, EPA in the past has issued CTGs that describe
the presumptive norm for RACT controls for a given industry, but that
allow for case-by-case considerations for a given source. Where States
wished to require source owners to conduct such a site-specific
analysis as part of the control technology review, EPA supports this
type of process. On the other hand, EPA does not believe it would be
appropriate to require all RACT-eligible sources to conduct such an
analysis, given that States have the primary responsibility for
identifying and analyzing measures for such sources.
5. What Factors Should States Consider in Determining Whether an
Available Control Technology or Measure Is Economically Feasible?
a. Background
The follow provides guidance for States to consider in determining
whether an available control technology is economically feasible for
purposes of identifying reasonably available control measures. This
guidance is slightly modified from our proposal.
b. Final Rule
Economic feasibility encompasses considerations such as whether the
cost of a potential measure is reasonable considering attainment needs
of the area and the costs of other measures, and whether the cost of a
measure is reasonable for the regulated entity to bear, in light of
benefits.
While many States generally establish RACT requirements for a
category of sources, the Act does not require the same level of control
on all sources in a category, nor does the Act require that each source
be controlled individually. Similar sources may have different marginal
costs, profit margins and abilities to pass costs through to the
consumer. These factors are appropriate to consider in determining
whether a given level of control is appropriate for an individual
source or category of sources. Accordingly, there is no presumption
that a given source must bear a cost similar to any other source.
States should consider the capital costs, annualized costs, cost
effectiveness of an emissions reduction technology, and effects on the
local economy in determining whether a potential control measure is
reasonable for an area or State. One available reference for
calculating costs is the EPA Air Pollution Control Cost Manual,\31\
which describes the procedures EPA uses for determining these costs for
stationary sources. The above costs should be determined for all
technologically feasible emission reduction options if such measure is
inherently ``reasonably available'' (e.g., not absurd or clearly
impractical). States may give substantial weight to cost effectiveness
in evaluating the economic feasibility of an emission reduction
technology. The cost effectiveness of a technology is its annualized
cost ($/year) divided by the emissions reduced (i.e., tons/year) which
yields a cost per amount of emission reduction ($/ton). Cost
effectiveness provides a value for each emission reduction option that
is comparable with other options and other facilities. Where multiple
control options exist for a given source or source category, States
should consider both the cost effectiveness (dollars per ton) of each
option, and the incremental cost effectiveness per ton between the
options (incremental increase in cost between options divided by the
incremental tons reduced).
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\31\ EPA Air Pollution Control Cost Manual--Sixth Edition (EPA
452/B-02-001), EPA Office of Air Quality Planning and Standards,
Research Triangle Park, NC, Jan 2002.
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In determining whether a given measure is reasonable, States may
consider costs per ton of other measures previously employed to reduce
that pollutant, but similar costs are not conclusive. As discussed
above, States may evaluate equity considerations in weighing the economic
feasibility of imposing a measure on a given source or source category.
We anticipate that States may decide upon RACT and RACM controls
that differ from State to State, based on the State's determination of
the most effective strategies given the relevant mixture of sources and
potential controls in the relevant nonattainment areas, and differences
in the difficulty of reaching attainment.
In considering what level of control is reasonable, EPA is not
proposing a fixed dollar per ton cost threshold for RACT, consistent
with the views of multiple commenters. Areas with more serious air
quality problems typically will need to obtain greater levels of
emissions reductions from local sources than areas with less serious
problems. Where essential reductions are more difficult to achieve
(e.g., because many sources are already controlled), the cost per ton
of control may necessarily be higher.
It is not appropriate to assume that the same cost per ton range is
reasonable for direct PM2.5 and different precursors,
because an equal amount of emission reduction in different pollutants
has a different impact on PM2.5 ambient levels. For example,
in a given nonattainment area, reductions of direct PM2.5
emissions may prove more expensive than reductions of NOX
emissions, but the resulting benefits of reductions of direct
PM2.5 might warrant the higher costs. A State should
consider this differential impact on ambient PM2.5 in
considering RACT for controlling different pollutants. During the SIP
process, States and regional planning organizations typically conduct
sensitivity modeling that can provide this information. Also, the PM
NAAQS RIA provides information on the differential impact of
PM2.5 and PM precursor reductions on ambient
PM2.5 levels in various areas.\32\
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\32\ See: U.S. EPA 2006. Regulatory Impact Analysis for the
Particulate Matter National Ambient Air Quality Standards. Air
Benefits and Cost Group, Office of Air Quality Planning and
Standards, Research Triangle Park, NC, October 6, 2006. Appendix A
provides an analysis of estimated benefits and costs of attaining
the 1997 PM NAAQS standards in 2015.
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One of the factors that could affect estimated compliance costs of
an emission reduction measure is the timing of its implementation.
Hypothetically, if a short compliance period were contemplated for a
set of sources, and if the short compliance
[[Page 20620]]
period resulted in high demand for a limited supply of labor or other
resources, compliance costs could be higher than if the same measure
were implemented by a later compliance date. In such a case it may be
reasonable for the State to find that the measure is reasonable only if
implemented by the later date.
If a source contends that a source-specific RACT level should be
established because it cannot afford the technology that appears to be
RACT for other sources in its source category, the source can support
its claim with such information as:
--Fixed and variable production costs ($/unit)
--Product supply and demand elasticity,
--Product prices (cost absorption vs. cost pass-through),
--Expected costs incurred by competitors,
--Company profits once the technology or measure is in operation
(considering the annualized costs and the marginal costs of alternative
technologies and measures),
--Employment costs, and
--Any other unique factor(s) particular to the individual source.
Finally, the EPA clarifies that if the State demonstrates through
economic analysis that the imposition of the measure would cause
unacceptable economic disruption for the local economy, that is, a
plant shutdown or a severe curtailment in plant employment or output, a
State may reject the measure as not reasonable to reach attainment as
expeditiously as practicable.
c. Comments and Responses
Comment: Some commenters agreed with EPA's proposal not to
establish presumptive cost-effectiveness thresholds.
Response: The EPA agrees with the commenters.
Comment: A number of commenters expressed concerns over the
references to health benefits as a consideration in whether measures
are technically or economically available. Some commenters believed
this is a consideration not authorized by the CAA. Others believed that
consideration of benefits, in combination with EPA's estimates of
benefits per ton, would have the effect of converting RACT to more
stringent LAER levels. Some commenters expressed concerns whether
States had the resources or expertise to conduct cost-benefit analyses
for this purpose.
Response: The EPA wishes to clarify that the reference to health
benefits does not mean that a cost-benefit, or a detailed health
benefits assessment, is a necessary part of a control strategy
demonstration. We also wish to clarify that EPA is not requiring that
the costs of all technologies and measures for PM2.5 and
precursors be deemed acceptable at any dollar/ton levels at or below
the calculated monetized benefits per ton of reduction. We do, however,
continue to believe that the significant benefits associated with
PM2.5 ambient reductions is a relevant consideration in
control strategy development. The EPA disagrees that this limited
consideration of benefits would convert the RACT process to the
equivalent of LAER.
Comment: One commenter objected to EPA's proposed requirement that
States consider competitive factors such as production costs, demand
elasticity, product prices, and cost incurred by competitors in the
determination of RACT. The commenter believed that this information is
generally not accessible to States or industrial facility owners, and
is not necessary for a RACT determination.
Response: The EPA generally disagrees that this type of information
is unavailable. For example, EPA calculates or reviews this type of
data on a regular basis as part of our work on MACT, NSPS, and other
emissions standards. A document that describes these types of analyses
and the data used to prepare them is the OAQPS Economic Resource Manual
found at http://www.epa.gov/ttn/ecas/analguid.html. EPA believes that
this issue is most relevant to category-wide RACT rules where a source
seeks a case-by-case exemption. Further, EPA believes most RACT
determinations will be developed through case-by-case analyses rather
than rules affecting entire source categories. Accordingly, this
analysis likely will be relevant in few cases.
6. What Specific Source Categories and Control Measures Should a State
Evaluate When Determining RACT and RACM for a Nonattainment Area?
a. Background
Section 172 does not provide a specific list of source categories
and control measures that must be evaluated for RACT and RACM for
PM2.5. However, section 172(c)(3) indicates that the
attainment plan must include a ``comprehensive, accurate, current,
inventory of actual emissions from all sources of the relevant
pollutant.'' This indicates that States should look broadly at the
different types of sources in the nonattainment area. We recognize that
PM2.5 is a new NAAQS without a long history of
implementation as with ozone. Therefore, we included a list of
potential RACM measures in the preamble to the proposed rule, based
upon a review of information about the contribution of various sources
to emissions inventories and a review of potential control measures for
such sources. We requested comment on the specific sources and
potential control measures recommended for RACM analysis on this list.
Based on comments received and additional information available to EPA
since the proposal, we have made some changes to the list. We also
refer to this list of potential ``RACT and RACM'' measures for the
combined approach to RACT and RACM in the final rule.
In the preamble to the proposed rule, EPA indicated that due to the
short time available, it does not plan to develop new control
techniques guidance (CTG) or ACT documents specifically for purposes of
PM2.5 implementation. The EPA indicated that other
information was available on control technologies, and EPA also
indicated its intention to maintain an updated list of references for
new PM2.5 control technology information.
b. Final Rule
Emission reduction measures constituting RACM should be determined
on an area-by-area basis. We believe that a State should consider each
of the measures listed in this section to determine if each measure is
reasonably available in the applicable nonattainment area. However, we
do not presume that each of these measures is reasonably available in
each nonattainment area.
We recommend that each State use the list of source categories in
this section as a starting point for identifying potentially available
control strategies (regulatory and voluntary) for a nonattainment area.
States are encouraged and expected to add other potentially available
measures to the list based on its knowledge of the particular universe
of emissions sources in the area and comments from the general public.
We expect that, depending on the potential measure being analyzed, the
State's degree of evaluation will vary as appropriate. Detailed
information on emission control technologies is available from a number
of sources.\33\ The EPA intends to maintain a website with links to
sources of information for
[[Page 20621]]
controlling emissions of direct particulate matter and PM precursors.
---------------------------------------------------------------------------
\33\ There are a number of sources of information on
technologies for reducing emissions of PM2.5 and its
precursors. Links are provided to a number of national, state and
local air quality agency sites from EPA's PM2.5 Web site:
http://www.epa.gov/pm/measures.html.
---------------------------------------------------------------------------
As discussed in section II.J.5. above, EPA recognizes that control
technology guidance for certain source categories has not been updated
for many years. Section 183(c) of the CAA, which addresses control
technologies to address ozone nonattainment problems, requires EPA to
``revise and update such documents as the Administrator determines
necessary.'' As new or updated information becomes available States
should consider the new information in their RACT determinations. A
State should consider the new information in any RACT determinations or
certifications that have not been issued by the State as of the time
such updated information becomes available.
Stationary Source Measures
--Stationary diesel engine retrofit, rebuild or replacement, with
catalyzed particle filter
--New or upgraded emission control requirements for direct
PM2.5 emissions at stationary sources (e.g., installation or
improved performance of control devices such as a baghouse or
electrostatic precipitator; revised opacity standard; improved
compliance monitoring methods)
--Improved capture of particulate emissions to increase the amount of
PM2.5 ducted to control devices, and to minimize the amount
of PM2.5 emitted to the atmosphere, for example, through
roof monitors
--New or upgraded emission controls for PM2.5 precursors at
stationary sources (e.g., SO2 controls such as wet or dry
scrubbers, or reduced sulfur content in fuel; desulfurization of coke
oven gas at coke ovens; improved sulfur recovery at refineries;
increasing the recovery efficiency at sulfuric acid plants)
--Energy efficiency measures to reduce fuel consumption and associated
pollutant emissions (either from local sources or distant power providers)
--Measures to reduce fugitive dust from industrial sites
Mobile Source Measures
--Onroad diesel engine retrofits for school buses,\34\ trucks and
transit buses using EPA-verified technologies
---------------------------------------------------------------------------
\34\ See Clean School Bus USA program at http://www.epa.gov/cleanschoolbus/.
See also: ``What You Should Know About Diesel
Exhaust and School Bus Idling,'' (June 2003, EPA420-F-03-021) at
http://www.epa.gov/otaq/retrofit/documents/f03021.pdf.
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--Nonroad diesel engine retrofit, rebuild or replacement, with
catalyzed particle filter \35\
---------------------------------------------------------------------------
\35\ See EPA's voluntary diesel retrofit program Web site at
http://www.epa.gov/otaq/retrofit/overfleetowner.htm.
---------------------------------------------------------------------------
--Diesel idling programs for trucks, locomotive, and other mobile
sources \36\
---------------------------------------------------------------------------
\36\ See EPA's voluntary diesel retrofit program Web site at
http://www.epa.gov/otaq/retrofit/idling.htm.
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--Transportation control measures (including those listed in section
108(f) of the CAA as well as other TCMs), as well as other
transportation demand management and transportation systems management
strategies \37\
---------------------------------------------------------------------------
\37\ See EPA's Web site on transportation control measures at
http://www.epa.gov/otaq/transp/traqtcms.htm.
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--Programs to reduce emissions or accelerate retirement of high
emitting vehicles, boats, and lawn and garden equipment
--Emissions testing and repair/maintenance programs for onroad vehicles
--Emissions testing and repair/maintenance programs for nonroad heavy-
duty vehicles and equipment \38\
---------------------------------------------------------------------------
\38\ See EPA's Web site on nonroad engines, equipment, and
vehicles at http://www.epa.gov/otaq/nonroad.htm.
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--Programs to expand use of clean burning fuels \39\
---------------------------------------------------------------------------
\39\ Fuels adopted in SIPs must be consistent with the Energy
Policy Act of 2005 and EPA guidance on SIP-approved boutique fuels
at 71 FR 78192 (December 28, 2006).
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--Low emissions specifications for equipment or fuel used for large
construction contracts, industrial facilities, ship yards, airports,
and public or private vehicle fleets
--Opacity or other emissions standards for ``gross-emitting'' diesel
equipment or vessels
Area Source Measures
--New open burning regulations and/or measures to improve program
effectiveness such as programs to reduce or eliminate burning of land
clearing vegetation
--Programs to reduce emissions from woodstoves and fireplaces including
outreach programs, curtailments during days with expected high ambient
levels of PM2.5, and programs to encourage replacement of
woodstoves when houses are sold
--Controls on emissions from charbroiling or other commercial cooking
operations
--Reduced solvent usage or solvent substitution (particularly for
organic compounds with 7 carbon atoms or more, such as toluene, xylene,
and trimethyl benzene)
Category-Specific Guidelines on innovative approaches. The EPA has
issued a number of category specific guidelines on approaches to taking
into account innovative approaches to emissions reductions for purposes
of SIPs. Categories currently covered by these guidelines include: (1)
Electric-sector Energy Efficiency and Renewable Energy Measures; (2)
Long Duration Switch Yard Locomotive Idling; (3) Long Duration Truck
Idling; (4) Clean Diesel Combustion Technology; and (5) Commuter Choice
Programs. See http://www.epa.gov/ttn/airinnovations/measure_specific.html.
c. Comments and Responses
Comment: Some commenters recommended that EPA provide new CTGs or
other control technology review documents for purposes of assisting
States to address PM2.5 and its precursors, because the
information in some current documents is out-dated.
Response: The EPA recognizes that issuance of new or updated CTGs
specifically tailored for PM2.5 would be useful.
Unfortunately, limitations on time and resources preclude EPA from
developing such CTGs in advance of the SIP submission date. The EPA
cannot delay the statutorily specified outer date for SIP submission.
However, EPA believes that there are already many sources of
information and guidance on key source categories. To the extent that
States need to examine potential control measures for sources never
addressed before in any area or other context for a previous NAAQS, EPA
anticipates that it will work closely with States during the process of
plan development and approval to ensure an appropriate approach.
Comment: A number of commenters expressed concerns with references
to the STAPPA and ALAPCO Menu of Options document. Some commenters
believed that this document must be subject to formal review and
comment to ensure appropriate stakeholder input.
Response: The language in the final preamble has been changed to
refer to a Web site EPA maintains that provides access to a variety of
information sources regarding control technologies that may be useful
to States to consider in developing their PM2.5 SIPs. These
links include evaluations developed by government and nongovernment
organizations. One such source with potentially useful information is
the STAPPA and ALAPCO Menu of Options. However, EPA is not specifically
endorsing any of the specific evaluations as being appropriate in any
specific situation. Rather, we think documents such as the
[[Page 20622]]
Menu of Options provide potentially useful ideas. Specifically, States
would need to assess which items on the menu are applicable in their
areas, and will have to assess the costs of applying controls locally.
Accordingly, there would be ample opportunity for public review of the
State's analysis of the local cost and air quality impacts of any
measure listed in the document which is included in a State's SIP. The
EPA is not requiring that States adhere to the list of measures in the
Menu of Options. The EPA does not in any way mean to imply that the
measures in the Menu of Options are presumed to be RACM, merely that
they are potential controls for areas to consider. The Menu of Options
has no regulatory significance and thus need not be issued through
notice-and-comment rulemaking. The EPA notes, however, that the Menu of
Options does provide a broad list of potential sources and measures
that can help inform States in the development of their plans.
Similarly, our own list of potential measures is not intended to be a
categorical list of measures which States must adopt, rather it is
intended to provide guidance about the types of sources and measures
that States can consider in constructing their attainment plans. The
EPA emphasizes that whether a source category or potential measure is
or is not on this list is simply not conclusive as to whether a given
measure is appropriate to consider in the RACT and RACM analysis. That
can be determined only through the State's development of the
attainment plan, and EPA's evaluation of such plan.
Comment: A commenter representing the paper industry interpreted
the proposed rule as requiring electrostatic precipitator and tighter
sulfur-in-fuel requirements for the forest products industry. The
commenter believed that EPA was creating limits for such sources
without adequate rulemaking process.
Response: The EPA disagrees that the listing of control
technologies in the table in the rule creates a ``rebuttable
presumption.'' Rather, the table identifies potential opportunities for
emissions reductions which should be reviewed in light of technical and
economic feasibility, and which a State should consider in a list of
possible RACT and RACM measures for purposes of attaining the standards
as expeditiously as practicable. The EPA is currently conducting a
sector-based approach to the paper industry. One of the goals of the
sector initiative on pulp and paper is to work with the industry to
identify reductions in SO2 and PM2.5 that will
assist us in meeting the NAAQS, considering facility locations,
magnitude of emissions, emission stream characteristics, and cost
effectiveness of controls.
Comment: A number of commenters believed that EPA should develop
not only a list of measures to consider for RACM, but should develop a
list of mandatory measures that States should include, particularly for
areas with attainment dates more than 5 years after designation.
Response: See discussion in section II.D.3 regarding rule
requirements for attainment date extensions and the issue of whether
certain measures should be mandatory in order for an area to receive an
extension.
Comment: Some commenters believed that the list of possible
measures was deficient in not including sources of PM2.5 and
PM2.5 precursors from agricultural sources. One commenter
believed the list is incomplete without identifying the contribution of
ammonia emissions associated with livestock, poultry, and crop fertilizers.
Response: As we indicated in the proposal, we included a list of
potential RACM measures in the preamble to the proposed rule, based
upon a review of information about the contribution of various sources
to the emissions inventories and a review of potential control measures
for such sources. We did not identify emissions from agricultural
sources in this review. Because ammonia is not presumed to be a
PM2.5 precursor unless identified for a specific area by the
State or EPA, regulation of ammonia emissions from agricultural sources
may not be necessary.
We also note that the agricultural industry presents unique
challenges to regulators given the nature of relevant emissions
sources. Moreover, we currently lack good methods to quantify
agricultural emissions, and we do not fully understand their
contribution to nonattainment problems. We have entered into an
agreement with several animal producer sectors to monitor animal
feeding operations to develop better tools to assess emissions from
this industry. Hopefully, these tools will enhance our knowledge of
agricultural emissions and their contribution to nonattainment
problems. Until emissions from these sources are better understood,
States should be judicious in determining whether any specific measure
is RACT/RACM for this industry.
The EPA recognizes that the United States Department of Agriculture
(USDA) has been working with the agricultural community to develop
conservation systems and activities to control coarse particle
emissions. Based on current ambient monitoring information, these USDA-
approved conservation systems and activities have proven to be
effective in controlling these emissions in areas where coarse
particles emitted from agricultural activities have been identified as
a contributor to a violation of the PM10 NAAQS. The EPA has
found that where USDA-approved conservation systems and activities have
been implemented, these systems and activities have satisfied the
Agency's reasonably available control measure and best available
control measure requirements for areas needing to attain the
PM10 standards.
The EPA believes that in the future, certain USDA-approved
conservation systems and activities that reduce agricultural emissions
of fine particles may be able to satisfy the requirements of applicable
sources to implement reasonably available control measures for purposes
of attaining the PM2.5 NAAQS. The EPA will work with States
to identify appropriate measures to meet their RACM requirements,
including site-specific conservation systems and activities. The EPA
will continue to work with USDA to prioritize the development of new
conservation systems and activities; demonstrate and improve, where
necessary, the control efficiencies of existing conservation systems
and activities; and ensure that appropriate criteria are used for
identifying the most effective application of conservation systems and
activities.
Comment: Some commenters raised concerns about a statement in the
proposal that ``[i]n addressing a nonattainment area having military
training, testing and operational activities occurring within it, the
State should not need to target these activities for emission
reductions.'' Some commenters interpreted this statement as an
exemption from any emission reduction requirements for military sources.
Response: The statement in the proposal was not intended as an
exemption for all military activities. Emissions potentially
contributing to PM2.5 concentrations at military
installations originate from a variety of sources: basic operational
activities (such as power generation, other fuel combustion, and
transportation to and from residences, offices, and schools); and from
field training and testing activities (such as personnel training,
obscurants used in training, operation of nonroad vehicles and
equipment, and related prescribed burning operations). The EPA believes
that in evaluating emissions for a specific nonattainment
[[Page 20623]]
area having military activities occurring within it, the State should
consult with DOD for information on the nature of these activities and
their associated emissions.
With regard to military training activities specifically, such
activities are periodic in nature, and when they do occur, the
principal type of emissions generated by these activities is dust (i.e.
inorganic direct PM emissions) from field operations. Other pollutants
may be emitted to a lesser degree from certain onroad and nonroad motor
vehicles. While military training activities may contribute some degree
of primary PM2.5 emissions to certain nonattainment area
inventories, the fugitive dust generated from military training
activities is predominantly composed of coarse PM rather than fine PM.
Based on data from the PM2.5 speciation monitoring
network operated by EPA and the States, the contribution of inorganic
dust to total PM2.5 mass on an annual average basis is
relatively low in most nonattainment areas, on the order of 0.5 to 1.5
micrograms per cubic meter (generally 10% or less of total
PM2.5 mass). Dust from military training activities would be
a subset of these levels. Depending on the available information and
specific circumstances for a particular area, a State could find in its
SIP development analyses that direct PM2.5 emissions from
military training activities do not significantly contribute to
PM2.5 concentrations in the nonattainment area, and
therefore would not need to target military training activities for
emission reductions in its attainment plan.\40\
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\40\ Windblown dust from agricultural tilling activities also
can be a periodic source of inorganic PM in some areas. In some
cases such dust would be expected to be predominantly composed of
coarse PM rather than fine PM. Depending on the available
information and specific circumstances for a particular area, it is
possible that a State could find in its SIP development analyses
that direct PM2.5 emissions from agricultural tilling
activities do not significantly contribute to annual average
PM2.5 concentrations in the nonattainment area, and
therefore would not need to require emission reductions from
agricultural tilling activities in the plan for attaining the annual
standard. However, States should be mindful of the contribution of
these sources to 24-hour fine particle concentrations.
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7. How Should States Consider EGU Reductions for CAIR in Meeting RACT/
RACM Requirements?
a. Background
In section III.I.11 of the preamble to the proposed rule, we
discussed the nature of the SO2 and NOX RACT
obligations of electric generating unit (EGU) sources in states subject
to the CAIR emission reduction requirements. The CAIR rulemaking was
finalized in March 2005 and published at 70 FR 25221 (May 12, 2005).
CAIR requires 28 states and the District of Columbia to significantly
reduce emissions of SO2 and/or NOX. The 26
jurisdictions in the CAIR PM2.5 region are required to
reduce annual emissions of SO2 and NOX, and the
26 jurisdictions in the CAIR ozone region are required to reduce
seasonal emissions of NOX. These jurisdictions also have the
option of participating in EPA-administered annual SO2,
annual NOX, and seasonal NOX cap-and-trade
programs (the CAIR trading programs) to meet these emission reduction
requirements. In addition, in March 2006, EPA promulgated a Federal
implementation plan (FIP) to implement CAIR in these jurisdictions
until they have EPA approved CAIR SIPs in place (71 FR 25328, April 28,
2006). The FIP adopts, as the control measure, the CAIR trading
programs slightly modified to allow for Federal instead of State
implementation. When fully implemented, CAIR will reduce SO2
emissions in these jurisdictions by over 70 percent and NOX
emissions by over 60 percent from 2003 levels. This will result in $85
to $100 billion in health benefits and nearly $2 billion in visibility
benefits per year by 2015 and will substantially reduce premature
mortality in the eastern United States. The benefits will continue to
grow over time as the program is fully implemented (i.e., the
SO2 emission bank is depleted and the final cap is met), and
as growth in populations and the aging of the population continues
(which increases the susceptible population).
Sources subject to cap-and-trade programs such as the CAIR trading
programs generally have the option of installing emissions control
technology, adopting some other strategy to reduce emissions, or
purchasing emissions allowances and thereby effectively paying other
sources covered by the cap to reduce emissions. In the proposal, we
noted that a number of EGUs expected to be covered by the CAIR trading
programs are located in nonattainment areas. Based on emissions
projections for 2010 and 2015 using the Integrated Planning Model
(IPM), some of these EGUs are expected to comply with CAIR by
purchasing allowances under the trading program and some are expected
to comply by installing emission controls.
The proposal also described our past experience with the
implementation of the NOX SIP Call and our belief that many
power companies will develop their strategies for complying with CAIR
based, in part, on consultations with State and local air quality
officials in order to address local PM2.5 and ozone
attainment planning needs. The EPA suggested that consultations on
location of CAIR controls would be timely during State development of
the CAIR SIP, which is due in 2006, prior to the April 2008 deadline
for submitting PM2.5 nonattainment area SIPs.
The EPA proposed a determination that in States that fulfill their
CAIR SO2 emission reductions entirely through EGU emission
reductions (i.e. without reductions from non-EGU sources or allowing
non-EGU sources to opt-in to the CAIR SO2 trading program),
participation in the CAIR SO2 trading program would satisfy
the SO2 RACT requirement for the EGU sources. The EPA also
proposed that in states that fulfill their CAIR NOX emission
reductions entirely through EGU emission reductions, CAIR would satisfy
NOX RACT for the EGU sources, provided that those sources
with existing selective catalytic reduction (SCR) emission control
technology installed on their boilers operate that technology on a
year-round basis beginning in 2009. Note that direct PM2.5
emissions are not addressed by the CAIR program, and EPA did not
propose any determination that compliance with CAIR would satisfy RACT
for direct PM2.5 emissions. The proposal included a
discussion of the rationale for these proposed determinations for
SO2 and NOX, and requested comments on the issue.
b. Final Rule
As discussed in section II.F.2 on our overall policy for RACT and
RACM, we consider an area's obligation to implement RACT to be part of
the area's overall RACM obligation--to adopt those reasonably available
measures needed to reach PM2.5 attainment as expeditiously
as practicable. The final rule also reflects this combined RACT/RACM
approach regarding EGU control obligations under CAIR and the extent to
which meeting CAIR also satisfies a source's RACT and RACM requirements
for attainment.
Specifically, the final rule includes a presumption that in States
that fulfill their CAIR SO2 emission reduction requirements
entirely through EGU emission reductions (i.e. without reductions from
non-EGU sources or allowing non-EGU sources to opt in to the CAIR
SO2 trading program), compliance by EGU sources with an EPA-
approved CAIR SIP or a CAIR FIP would satisfy their SO2
RACT/RACM requirements for attaining the fine particle NAAQS. This
section also includes a presumption that in States
[[Page 20624]]
that are subject to CAIR annual NOX emission reduction
requirements and fulfill these requirements entirely through EGU
emission reductions (i.e. without reductions from non-EGU sources or
allowing non-EGU sources to opt in to the CAIR annual NOX
trading program), compliance by EGU sources with an EPA-approved CAIR
SIP or a CAIR FIP would satisfy the NOX RACT/RACM
requirement for the PM2.5 NAAQS, provided that the sources
with existing selective catalytic reduction (SCR) emission control
technology installed on their boilers operate that technology on a
year-round basis beginning in 2009. This final position is based on a
number of factors identified in the proposal and discussed below.
Many PM2.5 nonattainment areas are projected to achieve
significant SO2 and NOX reductions under the CAIR
program. We do not believe that requiring source-specific RACT/RACM
controls on specified EGUs in nonattainment areas would reduce total
SO2 and NOX emissions from sources covered by
CAIR below the regionwide levels that will be achieved under CAIR
alone. Nor do we believe that ``beyond CAIR'' EGU controls for
SO2 and NOX are ``reasonably available'' control
measures for most areas within the CAIR Region. Accordingly, most
States need not evaluate additional control measures on EGUs to satisfy
RACT/RACM requirements as explained above.
As discussed previously, we are not requiring that States impose
RACT on any specific size or type of source. Instead, States must
conduct a RACT/RACM analysis considering measures that are ``reasonably
available'' to meet the overarching requirement to attain the standards
as expeditiously as practicable. Thus, the final rule imposes no
specific requirement on States to impose RACT/RACM on EGUs.
Nonetheless, in evaluating RACT/RACM for EGUs, EPA believes it is
appropriate for States (states that achieve all reductions from EGUs)
to consider the special attributes of that group of facilities
including the unique interrelated nature of the power supply network,
and their participation in the CAIR program. For EGUs in the CAIR
region, based upon the presumption explained here, States may define
RACT/RACM as the CAIR level of control on the collective group of
sources in the region rather than impose a specific level of control on
an individual source. This approach is similar to the Agency's past
``bubble'' policy, as discussed in section (c) addressing comments on
the proposal.
As discussed more fully in the CAIR final rulemaking notice, EPA
has set the 2009 and 2010 CAIR caps for SO2 and
NOX at a level that will require EGUs to install emission
controls on the maximum total capacity on which it is feasible to
install emission controls by those dates. The EPA concluded that the
CAIR compliance dates represent an aggressive schedule that reflects
the limitations of the labor pool, and equipment/vendor availability,
and need for electrical generation reliability for installation of
emission controls.
Although the actual SO2 cap does not become effective
until 2010, we designed banking provisions in CAIR so that covered EGUs
will begin to reduce their SO2 emissions almost immediately
after CAIR is finalized, and will continue steadily to reduce their
emissions in anticipation of the 2010 cap and the more stringent cap
that becomes effective in 2015. The 2015 SO2 and
NOX caps are specifically designed to eliminate all
SO2 and NOX emissions from EGUs that are highly
cost effective to control (the first caps represent an interim step
toward that end).
Moreover, we predicted that the majority of large coal-fired
utilities will install advanced control technologies under CAIR because
the larger and higher emitting source offer an opportunity to obtain
more cost-effective emissions reductions. We expect that the largest-
emitting sources will be the first to install SO2 and
NOX control technology and that such control technology will
gradually be installed on progressively smaller-emitting sources until
the ultimate cap is reached. As a result, few, if any coal-fired units
with greater than 600 MW of operating capacity should operate in
PM2.5 nonattainment areas without advanced control after
full implementation of CAIR. Of the remaining units operating without
advanced pollution controls, a great many of these units will have
operating capacities below 300 MW. We predict that these units ``will
be utilized less often,'' and ``typically have baghouses and
electrostatic precipitators for particulate control, have combustion
controls for NOX control, and burn low-sulfur coal.'' See
``Contributions of CAIR/CAMR/CAVR to NAAQS Attainment: Focus on Control
Technologies and Emission Reductions in the Electric Power Sector,''
Office of Air and Radiation, U.S. Environmental Protection Agency,
April 18, 2006 (available at http://www.epa.gov/airmarkets/cair/analyses/
naaqsattainment.pdf). In light of these expected results, we
generally believe that the cost to install additional controls on these
smaller units would be unreasonable.
We are also concerned that if States require specific EGUs to
install advanced pollution control measures, it could interfere with
the market-based incentives inherent in the cap and trade program. This
could increase the cost of compliance and shift the location of the
units that would otherwise opt to install advanced emissions controls.
Such a result may be counterproductive to that State's attainment
efforts, as the State may forego a larger quantity of more beneficial
reductions in transported pollutants, in exchange for a smaller
quantity and less beneficial reduction in local emissions. Moreover, it
may reduce the benefits expected in other nonattainment areas as well.
Accordingly, even if a State found the cost to control an individual
unit acceptable on a cost per ton basis, the potential overall
disbenefit of control may nonetheless make imposition of the control
not ``reasonably available.''
The EPA finds that the control installations projected to result
from CAIR NOX and SO2 caps in 2009 and 2010 are
as much as feasible from EGUS across the CAIR Region by those dates. In
fact, if states chose to require smaller-emitting sources in
nonattainment areas to meet source-specific RACT requirements by 2009,
they would likely use labor and other resources that would otherwise be
used for emission controls on larger sources. Because of economies of
scale, more boiler-makers may be required per megawatt of power
generation for smaller units than larger units. In this case, the
imposition of source-specific RACT/RACM on smaller emitting sources by
2009 could actually reduce the amount of banking that would otherwise
occur and result in higher SO2 emissions in 2009 as compared
to the level that would result from implementation of CAIR alone.
In any event, the imposition of source-specific control
requirements on a limited number of sources also covered by a cap-and-
trade program would not reduce the total regionwide emissions from
sources subject to the program. Under a cap-and-trade program such as
CAIR, a given number of allowances are issued in order to achieve a
given emission level. Source-specific control requirements within the
CAIR program may affect the temporal distribution of emissions (by
reducing banking and thus delaying early reductions) or the spatial
distribution of emissions (by moving them around from one place to
another), but they would not affect total regional emissions under the
program. If source-specific requirements were targeted at the units
[[Page 20625]]
that could be controlled most cost-effectively, then the imposition of
source-specific controls would likely achieve the same result as the
cap-and-trade program. If not, however, the imposition of source-
specific requirements would make any given level of emission reduction
more costly than it would be under the cap-and-trade program alone.
Thus, the imposition of source-specific RACT on EGUs covered by CAIR
would not reduce total regionwide emissions, but would likely achieve
emission reductions under the program in a more costly way.
Given the considerations described above, we think that in many
areas additional controls on EGUs generally would not be ``reasonably
available.'' Notwithstanding these conclusions, we recognize that
States are in the best position to determine how best to achieve
attainment with the PM2.5 NAAQS in light of local needs and
conditions. As we acknowledged in our proposed rule, power plant
operators typically have ongoing relationships with the State and local
officials involved in air quality planning. We expect that power plants
will continue to collaborate with State officials to determine how best
to address multiple air quality goals, and which plant locations to
control under CAIR, considering local PM2.5 and ozone
attainment needs.
The EPA expects States and local air agencies to identify
reasonably available control measures that are necessary and reasonable
to attain the standards as expeditiously as practicable; and that after
consulting with power companies, the State may conclude that
establishing additional ``beyond CAIR'' emission control requirements
on specific sources in nonattainment areas is warranted to provide for
attainment as expeditiously as practicable. Nevertheless, in preparing
the overall attainment demonstration, States should be aware of the
expected benefits of the market-based incentives of the CAIR program,
the cost effectiveness of control, feasibility of implementation, and
any disbenefits that would result from requiring ``beyond CAIR''
controls on any specific EGU before concluding that additional controls
on EGUs are ``reasonably available'' and necessary to satisfy RACT/RACM
requirements.
Year-round NOX controls. In the CAIR final rulemaking
notice, EPA found that the operation of existing SCRs on a year-round
basis, instead of operating them only during the ozone season, could
achieve NOX reductions at low cost relative to other
available NOX controls. The EPA projected that power
generators would employ this control measure to comply with CAIR SIPs.
Based on this control opportunity, EPA estimated the average cost of
non-ozone-season NOX control at $500/ton. These
considerations support a finding that RACT should include year-round
operation of existing SCRs that are located in PM2.5
nonattainment areas. Because all PM2.5 nonattainment areas
violate the annual form of the PM2.5 standard and public
health can be affected by high PM2.5 levels in the winter as
well as the summer, we believe that year-round operation of existing
SCR that are located in nonattainment areas where NOX is an
attainment plan precursor will provide additional health benefits for
relatively low dollar cost per ton of pollutant reduced.
In the proposal notice, EPA proposed to define ``existing'' SCRs as
those units that were in place by the date of the proposed rule
(November 1, 2005). We selected this date rather than the final date to
avoid creating an incentive to delay installation of new SCR. Today, we
finalize our proposed approach with one clarification. To avoid
confusion over the proper interpretation of the phrase ``in place,'' we
are clarifying that an existing SCR is one which is fully installed and
capable of operation by November 1, 2005.
We also proposed that these existing SCR begin year-round
operations no later than January 1, 2009 to qualify as RACT/RACM under
our presumptive approach. We noted that year round operation of
existing SCR involves little to no alteration of existing equipment,
and that EGUs could conduct any required work during normal outages.
Today, after taking these factors into account, we finalize our
proposed rule. The year-round operation requirement, however, will not
be federally enforceable to individual EGUs until EPA approves a
State's SIP including the requirement.
c. Comments and Responses
Comment: Some commenters supported the proposed determination
described in section (a) that in States that fulfill their CAIR
SO2 emission reduction requirements entirely through EGU
emission reductions (i.e. without reductions from non-EGU sources or
allowing non-EGU sources to opt in to the CAIR SO2 trading
program), compliance by EGU sources with an EPA-approved CAIR SIP or a
CAIR FIP would satisfy the SO2 RACT requirement for the
sources; and in States that are subject to CAIR annual NOX
emission reduction requirements and fulfill these requirements entirely
through EGU emission reductions (i.e. without reductions from non-EGU
sources or allowing non-EGU sources to opt in to the CAIR annual
NOX trading program), compliance by EGU sources with an EPA-
approved CAIR SIP or a CAIR FIP would satisfy the NOX RACT
requirement for the sources, provided that the sources with existing
selective catalytic reduction (SCR) emission control technology
installed on their boilers operate that technology on a year-round
basis beginning in 2009. One commenter supported EPA's approach so long
as States may pursue additional reductions from EGUs if needed for
attainment as expeditiously as practicable. A number of other
commenters opposed the proposed determination regarding RACT for EGUs
based on a number of issues.
Response: Based on the rationale described in the sections above,
the final rule includes a presumption that compliance with CAIR
satisfies SO2 and NOX RACT/RACM requirements for
EGUs in many areas. Nonetheless, States can require ``beyond CAIR'' EGU
controls if a State determines that it is a necessary and reasonable
means to attain the PM2.5 standards. Comments opposing this
approach are addressed in more detail below.
Comment: A number of commenters objected to the proposed
determination, arguing that it would result in greater control
requirements and economic burden on non-EGU sources located in
nonattainment areas. These commenters urged EPA to adopt a final rule
that provides for implementing the most cost-effective controls
necessary to attain the standard. They assert that with the proposed
finding that compliance with CAIR satisfies RACT for EGUs, the proposed
rule would not provide for the most cost-effective approach to
attainment. They argue EPA and States should develop cost-effectiveness
guidance that includes all stationary source control measures and they
should develop SIPs based on the most economic means to attain the
standard. They make several arguments to support this position. The
commenters asserted that if an EGU control is more cost-effective than
a non-EGU control, the EGU should be subject to ``beyond-CAIR''
controls. They also asserted that if EPA chooses to consider the CAIR
rule as satisfying SO2 and NOX RACT for EGUs,
then other sources should not be subjected to control costs greater
than those found reasonable under CAIR (i.e., $800/ton). They believe
it would be inequitable to require smaller sources to pay a higher cost
for emissions reductions than larger sources, which are a more significant
[[Page 20626]]
contributor to the problem and which may be able to make more cost-
effective emission reductions. One commenter also suggested that EPA
should authorize a presumption that emissions reductions required on
electric utilities under the CAIR will be equivalent to RACT only if a
particular source in a CAIR State has installed controls that achieve
the average level of control that EPA has projected will occur for the
particular pollutant under the CAIR requirements.
Response: The EPA has determined that implementation of the CAIR
trading program represents highly cost-effective controls that will
achieve widespread regional SO2 and NOX emissions
reductions from EGUs and will provide significant air quality benefits
for ozone and PM2.5 nonattainment areas. In developing
attainment SIPs and identifying RACM, States will need to consider
additional cost-effective and reasonable controls to reach attainment
as expeditiously as practicable. The EPA does not agree with the
commenter's argument that controls on non-EGUs should be no more than
the projected cost of EGU controls under CAIR. The EPA expects that in
order to achieve attainment as expeditiously as practicable, some
States may need to adopt control measures for some sources which cost
more per ton but which still are considered to be reasonable and cost-
effective.
In addition, States must consider the economic feasibility of
implementing a given control measure. Because of facility-specific
factors, EPA believes it would be inappropriate to establish a
threshold of control effectiveness (e.g. dollars per ton) based on
control of EGUs and apply this threshold to all source categories. The
ability of a source to cost-effectively reduce emissions is dependent
on case-specific factors, including the ability of the given source to
sustain the cost of control, and prevailing costs in the specific
geographical location. A direct correlation between the size of an
emissions source and the economic feasibility of controls for that
source and location does not necessarily exist.
We also disagree with the commenter who suggests that RACT
requirements should only be satisfied if a source achieves an average
level of control that EPA projects to occur under CAIR. The EPA
maintains that the presumption that CAIR satisfies SO2 and
NOX RACT/RACM for EGUs in most areas is an appropriate
policy. As discussed further below, we have always recognized that
States could determine RACT for a single source or group of sources.
Comment: A number of commenters opposed the proposed determination
that CAIR would satisfy the SO2 and NOX RACT
requirement for EGUs. The commenters argued that this determination is
unlawful, that it does not comply with section 172(c)(1) of the CAA
which requires RACT (i.e. controls that are technologically and
economically feasible) ``at a minimum'' for all existing sources in the
nonattainment area, that it would allow very large stationary sources
to escape cost-effective controls entirely, and that it is largely
based on the legally-irrelevant contention that CAIR will reduce
emissions more cost-effectively than RACT. They claim that EPA has no
authority to displace the Congressionally-mandated RACT requirement,
that CAIR was designed to address regional pollution transport (not to
be an attainment strategy), and that EPA should remove these proposed
provisions in the final rule. Commenters claim that the EPA's proposed
approach to allow EGU emissions to be addressed solely through CAIR
would undermine states' efforts to meet the Federal PM2.5
health standard, particularly when EGU sources are among the most cost-
effective to control. Another commenter claimed that EPA's proposal
allowing States that choose to fulfill their CAIR requirements entirely
through emission reductions from EGUs to also use CAIR to satisfy their
SO2 and NOX PM2.5 RACT requirements,
thereby equating these two requirements for the EGU sector, is flawed.
This commenter argued that allowing a cap-and-trade program, such as
the CAIR, to substitute for the RACT requirement undermines the
effectiveness of the controls by allowing facilities to use allowances
to offset emissions, rather than control them at the source. The
purchase of allowances, they assert, does not satisfy RACT requirements.
Response: The EPA disagrees with these comments. The final rule
does not displace the RACT requirement for any sources. Instead, EPA is
exercising its authority to interpret the section 172 RACT and RACM
requirements for the purposes of implementing the 1997 PM2.5
standards. For the reasons described in section (b) above, we believe
that States can rely on EPA's presumption that compliance with a CAIR
SIP or FIP, meeting certain requirements, will satisfy the RACT/RACM
requirement for certain EGU sources. The EPA historically issued
control technology guidelines setting forth presumptive levels of
emissions control that satisfy the RACT requirement for a given
industry. The final rule is similar to this practice in establishing a
presumption that SO2 and NOX reductions under the
CAIR program satisfy the RACT/RACM requirement for EGUs in CAIR States.
In identifying reasonably available control measures to ensure
attainment as expeditiously as practicable, States will need to take
CAIR reductions into account as well as any additional cost-effective
reductions that are technologically and reasonably available.
We further find that the attempt by many commenters to characterize
CAIR as a strategy to address only regional pollution transport and not
an attainment strategy as overly simplistic. The EPA analyses for CAIR
show that there are significant air quality benefits projected for
individual nonattainment areas as a result of SO2 and
NOX reductions across the multistate CAIR region. The Act
does not prevent States from properly crediting measures that achieve
multiple objectives (e.g. regional transport or local nonattainment).
Moreover, Section 110(a)(2)(D) requires SIPs to contain adequate
provisions to assure that sources in the State do not contribute
significantly to nonattainment in any other State. The CAIR rule is an
integral element in meeting the States' Section 110 attainment
obligations. Accordingly, it is reasonable to incorporate this
consideration in determining what measures qualify as RACT/RACM.
Finally, EPA does not interpret the provisions of Section 172(c)(1)
related to the RACT requirement as precluding States' use of a cap and
trade approach as a means of regulating existing sources and achieving
RACT/RACM reductions, especially in light of Congresses' expressed
authorization to auction emission rights in Section 172(c)(6).
The EPA has long recognized that RACT need not apply to individual
sources. As stated earlier, our early guidance on RACT requirements
stated that States could establish RACT for an ``individual sources or
a group of sources.'' (emphasis added) See Memo. Strelow (Dec. 1976)
and 44 FR 71779. Importantly, Congress ratified the early
interpretations of RACT and RACM when it enacted the 1990 Amendments.
See 42 U.S.C. Section 7515 (Clean Air Act section 193). Our 1986
emissions trading policy also recognized a number of advantages offered
through application of a ``bubble'' approach including faster
compliance with RACT limits and earlier reductions. Moreover, Courts
have upheld EPA's approval of States' use of ``bubbling'' multiple
units to meet RACT requirements. See e.g.
[[Page 20627]]
Natural Resources Defense Council v. EPA, 941 F.2d 1207 (finding that
EPA need not adhere to a source specific RACT determination to satisfy
RACT requirements and acknowledging EPA's special knowledge and
expertise in the area.)
Comment: The EPA's proposal to allow EGU emissions to be addressed
solely through CAIR undermines prospectively States' efforts to meet
the Federal PM2.5 health standard. EGU sources are among the
most cost-effective to control.
Response: For the reasons described in section (b) above, EPA
believes that States can rely on EPA's presumption that compliance with
a CAIR SIP or FIP, meeting certain requirements, satisfies the
SO2 and NOX RACT/RACM requirement for certain EGU
sources. Areas can require ``beyond CAIR'' EGU controls if a State
determines that it is a necessary and reasonable means to attain as
expeditiously as practicable. Nonetheless, as discussed above, EPA
believes that implementation of the CAIR requirements will provide for
substantial progress in attaining the PM2.5 standards and
that States may presume that RACT/RACM requirements are equal to the
CAIR level of control.
Comment: CAIR fails to address the need for short-term reductions
in PM2.5 and precursor emissions on high pollution days.
While RACT restricts emissions over a 1-hour to 24-hour period, CAIR
only provides for an annual or seasonal cap. Reliance on CAIR therefore
fails to recognize the importance of reducing short-term emissions,
which was recently highlighted by the EPA's own proposal to tighten the
24-hour PM2.5 health standard. Local and short-term adverse
air quality effects of PM2.5, must be addressed in the final
rule by requiring RACT for all major facilities in addition to CAIR.
Response: The CAIR program is oriented toward reducing
SO2 and NOX emissions in order to reduce air
quality concentrations on an annual and seasonal basis. Because all
PM2.5 nonattainment areas were designated due to violations
of the annual standard (and the two designated areas in California also
violated the 24-hour standard), the focus of this implementation rule
is attainment of the annual standard. CAIR is projected to provide
significant air quality benefits in 2010 and 2015 for eastern
PM2.5 nonattainment areas on both an annual basis and on a
98th percentile 24-hour basis.\41\
---------------------------------------------------------------------------
\41\ See the regulatory impact analysis chapter on air quality
for the 2006 PM NAAQS review at
http://www.epa.gov/ttn/ecas/regdata/RIAs/Chapter%204-Air%20Quality.pdf.
---------------------------------------------------------------------------
Comment: The proposal is silent on the issue of whether EGUs are
subject to direct PM2.5 emissions RACT requirements. It is
critical that RACT be required for all facilities with respect direct
PM2.5 emissions, regardless of a facility's participation in CAIR.
Response: In the final rule and preamble, EPA has clarified that
all EGUs in nonattainment areas are subject to RACT/RACM for direct
PM2.5 emissions. The presumption described above applies
only to SO2 and NOX RACT/RACM, not RACT/RACM for
direct PM2.5 emissions from EGUs.
Comment: The EPA fails to consider the geographical distributional
impacts of the emission reductions. Equating CAIR with RACT fails to
take into account the substantial contribution that emissions from EGUs
within a nonattainment area may make toward that area's
PM2.5 nonattainment problem. The EPA does not attempt to
explain how such a generalized determination satisfies RACT for PM2.5.
Response: The establishment of recommended levels for RACT/RACM is
an area Congress delegated to the specific expertise of the Agency.
Based on our analysis, we conclude that the CAIR emissions caps
presumptively represent the level of emissions control achievable
through application of ``reasonably available'' control technologies.
Nonetheless, in developing attainment plans, each State will evaluate
the impact of stationary sources located within the nonattainment area
in developing its attainment strategies for the local area.
Comment: A few commenters stated that EPA should explain how this
proposal would be implemented for States that request an extension of
an attainment date because attaining in 5 years or less is
impracticable; i.e., whether EPA would still hold to its interpretation
that CAIR equals RACT for EGUs and not require additional reductions
from EGUs even if an area cannot attain in 5 years and controls on EGUs
could lead it to attain more expeditiously. These commenters argue
that, in considering if additional RACT is needed in states that obtain
extensions of the attainment deadline after 2010, EPA cannot ignore
potential RACT for electric generating units any more than they would
be allowed legally to avoid consideration of any other RACT candidates.
One commenter is particularly concerned that States would not include
EGUs in their RACT determinations and instead require smaller
industrial boilers or process heaters to control emissions.
Response: The EPA's determination regarding CAIR and RACT is not
limited to areas attaining within five years. The Agency's rationale is
presented in the ``final rule'' section above. We disagree that the
CAIR-RACT presumptions necessarily shift emission control burdens from
EGUs to smaller industry boilers and process heaters because, in
implementing the RACM requirement, the State may include an evaluation
of control options on those sources as part of their RACT/RACM
analyses. As stated above, EPA concluded that the CAIR compliance dates
represent an aggressive schedule that reflects the limitations of the
labor pool, and equipment/vendor availability, and need for electrical
generation reliability for installation of emission controls.
Accordingly, additional controls on EGUs may not be a reasonably
available control measure that can be effectively implemented in a
manner that advances an area's attainment date.
Comment: The EPA designated many partial counties nonattainment for
PM2.5 solely because the areas contained EGU emission
sources thought to cause or contribute to violations of the NAAQS. In
implementing attainment plans, it makes sense to consider further
control of these sources, and because they are located in nonattainment
areas, the ability to do so is provided for and legal under the CAA.
Response: The EPA designated PM2.5 nonattainment
counties because they either had a violating monitor or they
contributed to a nearby air quality problem. Importantly, EPA
designated these areas without considering the air quality benefits
expected in the future from CAIR. Accordingly, the fact that an EGU is
located in a partial county and we included the partial county in the
nonattainment area because we believe that the EGU was causing or
contributing to the nonattainment violations, does not equate with a
finding that more than CAIR is required to remedy the nonattainment
problem. Nonetheless, EPA believes that States should evaluate the
impact of stationary sources in all designated counties, including
those partial counties noted by the commenter, in its assessment of
reasonably available control strategies to ensure attainment as
expeditiously as practicable.
Comment: The EPA should adopt the Ozone Transport Commission's
(OTC's) approach to cap-and-trade programs. When the OTC developed its
NOX
[[Page 20628]]
Budget Program (which was the basis for EPA's NOX SIP call
and subsequently CAIR), it assumed that RACT was applied first. Thus
the cap-and-trade program operated in an environment that assumed RACT
was in force, not in lieu of RACT.
Response: Under the ozone national ambient air quality standards,
NOX and VOC RACT have been implemented progressively for the
past 30 years or more, prior to development of the NOX SIP
call regional control program. In contrast, the PM2.5
implementation program is the first instance in which we have required
RACT/RACM specifically for fine particle pollution. For this reason,
the CAIR program is not operating with SO2 and
NOX RACT limits already in place for attainment of the
PM2.5 standards. Nonetheless, as discussed above, EPA
believes that implementation of the CAIR requirements will provide for
substantial progress in attaining the PM2.5 standards and
that States may presume that RACT/RACM requirements are equal to the
CAIR level of control.
Comment: A few commenters stated that EPA should clarify and modify
the part of its proposal that explains why a State cannot rely on EPA's
determination that CAIR can satisfy the NOX RACT requirement
for PM2.5 if the State ``elect[s] to allow non-EGU sources
to voluntarily enter the EPA-administered CAIR trading program through
an opt-in provision in the CAIR model rule.'' (70 FR 66025 col. 3).
These commenters believe that this part of the proposal might be
construed to preclude States subject to both the NOX SIP
Call and included in the CAIR region for ozone from relying on the
NOX RACT determination for PM2.5 if the States
choose ``to bring their non-CAIR [including non-EGU] NOX SIP
Call trading sources into the CAIR ozone season NOX cap and
trade program.'' (70 FR 49708, 49728 col. 3) (August 24, 2005). The
commenters assert that EPA gave States the option of bringing non-EGU
NOX SIP Call sources into the CAIR seasonal NOX
trading program to ensure that non-CAIR sources, including non-EGUs,
that are subject to the NOX SIP Call rule would not be
``stranded,'' starting in 2009, by being left in an ozone season
NOX control program with no EGU trading partners. The
commenters argued that ``EGUs should not be penalized, in the form of
denial of CAIR-RACT treatment, as a result of States exercising their
option to avoid financial and compliance difficulties for non-EGUs that
otherwise would be left without allowance trading partners in the EGU
sector after the NOX SIP Call trading program ends in
2008.'' These commenters point to EPA's determination in the final
Phase 2 ozone implementation rule, that participation in the CAIR
trading programs can satisfy NOX RACT for ozone even if a
State brings non-EGUs in the NOX SIP Call trading program
into the trading program after 2008, see 70 FR 71657 col. 2, provided
the State retains an ``EGU [emission] budget under CAIR that is at
least as restrictive as the EGU budget that was set in the State's
NOX SIP call SIP,'' id. At 71658 col. 1. These commenters
argue that EPA should make a similar determination here regarding
NOX RACT for purposes of PM2.5 NAAQS implementation.
Response: All states with EPA approved CAIR SIPs or subject to a
CAIR FIP implementing the annual NOX emission reduction
requirements, and obtaining those reductions solely from EGUs may rely
on EPA's determination that CAIR presumptively satisfies NOX
RACT/RACM for PM2.5 for these sources. This determination is
unaffected by whether or not a State permits NOX SIP Call
non-EGUs to participate in the CAIR ozone season trading program. In
the final rule, we have included the presumption that NOX
RACT/RACM for PM2.5 is satisfied for EGUs complying with a
CAIR SIP or CAIR FIP implementing the annual CAIR NOX
emission reduction requirements (provided the State implementation of
the CAIR NOX annual trading program includes EGUs only).\42\
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\42\ EPA's CAIR-RACT presumption also would not apply if a State
required sources other than EGUs to achieve a portion of the
reductions required by CAIR (e.g., the State's CAIR SIP achieved
some reductions from EGUs but took credit for non-EGU reductions
achieved under new, more stringent requirements implemented to meet
NOX SIP call caps). Under the CAIR rule such a State would not
be eligible to participate in the EPA-administered CAIR trading system.
---------------------------------------------------------------------------
In the final ozone implementation rule, EPA addressed numerous
issues relating to the transition from the NOX SIP Call to
the CAIR ozone season trading program, including the impact of bringing
NOX SIP Call non-EGUs into the CAIR ozone season trading
program. Commenters' suggestion that these determinations are relevant
to this PM2.5 implementation rule ignores the fact that both
the NOX SIP Call and the CAIR ozone season trading program
are seasonal, not annual, trading programs. The NOX SIP Call
EGU and non-EGU budgets are seasonal NOX budgets and do not
address annual NOX emissions. As discussed above,
PM2.5 levels year-round contribute to an area's annual
average concentration, and NOX emissions during non-summer
months contribute to nitrate concentrations, which are typically
highest in cooler temperatures. For these reasons, EPA believes it
would be inappropriate to accept commenters' suggestion.
8. What Are the Required Dates for Submission and Implementation of RACT?
a. Background
The EPA requested comment on a general approach for the dates for
submission and implementation of RACT rules. The final rule retains the
proposed approach, as described in the following section.
b. Final Rule
The final rule requires the following:
(1) Date of submission. States must submit adopted RACT rules to
EPA within 3 years of designation, at the same time as the attainment
demonstration due in April 2008.
(2) Dates for implementation of control measures. States should
also implement any measures determined to be RACT expeditiously, as
required by section 172. Implementation of RACT measures should in no
case start later than the beginning of the year before the nominal
attainment date. For example, if an area has an attainment date of
April 2010, then any required RACT measures should be in place and
operating no later than the beginning of 2009. This is intended to help
provide for clean air in calendar year 2009. As discussed in section
II.D, if other criteria are also met, EPA could then grant the area a
1-year attainment date extension if the air quality level in the 3rd of
the 3 years was below the level of the standard. If the area observes a
second year of clean air, EPA could grant a second 1-year attainment
date extension. In this case, the 2009 to 2011 period would then be
reviewed to assess whether the area attains the standards.
(3) Provisions for a demonstration that additional time is needed.
While EPA expects that States will implement required RACT controls by
January 2009 in most situations, there may be cases where additional
time is needed to implement an innovative control measure or to achieve
a greater level of reduction through a phased approach. If a State has
provided an adequate demonstration showing that an attainment date
extension would be appropriate for an area, then the State may consider
phasing-in certain RACT controls after January 2009. The EPA would
allow the implementation of selected RACT controls after January 2009
if the State can show why additional time is needed for
[[Page 20629]]
implementation, and such delayed implementation still would need to be
on a schedule that provides for expeditious attainment. In no event
could the State wait to implement RACT controls until the last few
years prior to the attainment date without an adequate rationale for
why earlier implementation was not feasible.
c. Comments and Responses
Comment: One commenter supported EPA's position that implementation
of RACT and RACM by January 1, 2009 is necessary to achieve the effect
on air quality for calendar year 2009.
Response: The EPA agrees with this comment.
Comment: Some commenters supported allowing for an implementation
schedule that allowed for implementation of RACT and RACM for a time
frame extending beyond 2009. These commenters favored such an approach
if States provided an adequate demonstration of why the measures cannot
be implemented earlier. Commenters noted that a phased approach to
emissions reductions in some cases could lead to additional reductions
that could not occur by 2009.
Response: The EPA agrees with these comments.
Comment: One commenter believed that so long as a State
demonstrates attainment by 2015, EPA should not require implementation
of any RACT measures. The commenter further asserted that it would be
bad policy to require costly emissions reductions through imposition of
RACT on areas expected to attain the standards through other means by 2015.
Response: The EPA disagrees with this comment. The CAA requires
States to demonstrate that the attainment plan will attain the
standards as expeditiously as practicable and must include RACT and
RACM. The requirement for ``reasonable'' measures does not require that
any theoretical measure be implemented, but does require implementation
of those reasonable measures which could advance the attainment date by
at least 1 year. Given the health effects associated with
PM2.5, EPA believes this approach is sound public policy.
9. Which Pollutants Must Be Addressed by States in Establishing RACT
and RACM Limits in Their PM2.5 Attainment Plans?
a. Background
In the proposed rule, and in the final rule as discussed in detail
in section II.A above, EPA discusses the pollutants which States must
address in the attainment plans, in particular with respect to RACT,
RACM and NSR. These pollutants include not only direct
PM2.5, but also gaseous precursors to the formation of
PM2.5. In general, the decisions that States and EPA make
with respect to which precursors are significant contributors to an
area's PM2.5 nonattainment problem define the pollutants and
sources to be addressed by States in developing RACT and RACM.
b. Final Rule
In the final rule, in establishing RACT and RACM limits, those RACT
and RACM limits must address:
--Direct emissions of PM2.5
--SO2, a precursor to PM2.5 formation, and
--NOX, unless a State makes a finding that NOX
emissions from sources in the State do not significantly contribute to
the PM2.5 problem in a given nonattainment area.
The EPA generally presumes that RACT and RACM limits are not needed
for ammonia or VOC unless that State or EPA determines otherwise for a
given nonattainment area. RACT and RACM limits are needed for ammonia
if a State or EPA makes a finding that ammonia emissions significantly
contribute to the PM2.5 problem in a given nonattainment
area, and thus finds that control of ammonia would help address the
PM2.5 problem. RACT and RACM limits are needed for VOC only
if a State or EPA makes a finding that VOC emissions significantly
contribute to the PM2.5 problem in a given nonattainment
area. (As a point of clarification, ``VOCs,'' which are gaseous organic
precursors to the chemical formation of secondary organic aerosol, are
treated differently from semivolatile or nonvolatile organic compounds
which are addressed as directly emitted PM2.5). Issues
related to the finding of ``significant contribution'' for these
pollutants are discussed in Section II.A above.
10. Under the PM2.5 Implementation Program, When Does a
State Need To Conduct a RACT Determination for an Applicable Source
That Already Has a RACT, BACT, LAER, or MACT Determination in Effect?
a. Background
For PM2.5 nonattainment areas, States are required to
implement the RACT requirement to reduce emissions of direct
PM2.5 and PM2.5 precursors from applicable
sources. The EPA anticipates that for some sources located in
PM2.5 nonattainment areas, the State would have previously
conducted RACT determinations for VOC or NOX under the 1-
hour ozone standard, or for direct PM10 emissions under the
PM10 standards. Some of the RACT determinations established
under these other programs would be relatively recent while other
determinations may be more than 10 years old. In some cases, a new RACT
determination might reach the conclusion that the preexisting
determination is still valid and would require the installation of
similar control technology because the relevant pollutant was
addressed, the same emission points were reviewed, and the same
fundamental control techniques would still have similar costs. In other
cases, however, a new RACT analysis could determine, for example, that
better technology has become available, and that cost-effective
emission reductions are achievable.
In the proposed rule, the EPA requested comments on a general
approach to taking prior RACT determinations into account, and within
the general approach, invited comments on two specific questions: (1)
Should new RACT determinations be required for all existing
determinations that are older than a specified amount of time (such as
10 years old)?; and (2) what supporting information should a State be
required to submit as part of its certification to demonstrate that a
previous RACT analysis meets the RACT requirement currently for
purposes of the PM2.5 program?
In the proposed rule, EPA also noted that sources subject to RACT
may also have been subject to other prior technology determinations
such as BACT, LAER or MACT determinations. The proposed rule requested
comment on approaches to taking these prior technology determinations
into account.
b. Final Rule
The EPA has determined that it is appropriate to follow the
approach in the proposed rule, which is described below. State RACT
SIPs for PM2.5 must assure that RACT is met, either through
a new RACT determination or a certification that previously required
RACT controls represent RACT for PM2.5.
Where a State adopted and EPA approved a control measure as RACT
for a pollutant emitted from a specific stationary source or source
category under another NAAQS program, the State may submit as part of
its SIP revision a certification, with appropriate supporting
information, that the previous determination represents a current RACT
level of control for those emissions for purposes of the PM2.5
program. Otherwise, the State should revise the SIP to reflect a modified
[[Page 20630]]
RACT requirement for specific sources or source categories.
In cases where the State's prior RACT analysis under another NAAQS
program concluded that no additional controls were necessary, a new
RACT determination is required for that source. In cases where the
previous RACT determination did not require any controls on the source,
it is more likely that a new review might find that emission controls
are now economically and technically feasible. This is because
emissions reductions from a potential control measure are likely to be
greater, and the cost per ton of emission reduction is likely to be
lower, than in the case of a source that previously installed controls
to meet RACT under another program.
A RACT determination for a source or source category subject to a
prior RACT determination is also required for any pollutants that were
not the subject of the prior RACT determination, but which the State
has determined should be regulated for purposes of PM2.5.
The EPA advises that the State should closely review any existing RACT
determinations established under another NAAQS program. For RACT
certifications and determinations, States are to consider new
information that has become available since the earlier RACT
determination. For example, where updated information on control
technologies is presented as part of notice-and-comment rulemaking,
including a RACT SIP submittal for sources previously controlled,
States (and EPA) must consider the additional information as part of
that rulemaking. Existing EPA guidance on control technologies can be
used to help inform RACT decisions. However, EPA believes it may not be
sufficient for a State to rely on technology guidance that is several
years old and issued to provide recommendations on control measures and
levels for a different NAAQS in evaluating RACT for PM2.5.
With respect to prior technology determinations other than RACT,
the final rule provides that:
(1) Prior BACT and LAER Determinations. In many cases, but not all,
best available retrofit technology (BACT) or lowest achievable emission
rate (LAER) provisions for new sources would assure at least RACT level
controls on such sources. The BACT/LAER analyses do not automatically
ensure compliance with RACT since the regulated pollutant or source
applicability may differ and the analyses may be conducted many years
apart. States may, however, rely on information gathered from prior
BACT or LAER analyses for the purposes of showing that a source has met
RACT to the extent the information remains valid. We believe that the
same logic holds true for emissions standards for municipal waste
incinerators under CAA section 111(d) and NSR/PSD settlement
agreements. Where the State is relying on these standards to represent
a RACT level of control, the State should present its analysis with its
determination during the SIP adoption process.
(2) Compliance With MACT Standards Affecting VOC. In situations
where the State has determined VOC to be a significant contributor to
PM2.5 formation in an area, compliance with MACT standards
may be considered in VOC RACT determinations. For VOC sources subject
to MACT standards, States may streamline their RACT analysis by
including a discussion of the MACT controls and relevant factors such
as whether VOCs are well controlled under the relevant MACT air toxics
standard, which units at the facility have MACT controls, and whether
any major new developments in technologies or costs have occurred
subsequent to establishment of the MACT standards. We believe that
there are many VOC sources that are well controlled (e.g., through add-
on controls or through substitution of non-VOC non-HAP materials for
VOC HAP materials) because they are regulated by the MACT standards,
which EPA developed under CAA section 112. Any source subject to MACT
standards must meet a level that is as stringent as the best-controlled
12 percent of sources in the industry. Examples of these HAP sources
that may effectively control VOC emissions include organic chemical
plants subject to the hazardous organic NESHAP (HON), pharmaceutical
production facilities, and petroleum refineries.\43\ We believe that,
in many cases, it will be unlikely that States will identify VOC
emission controls more stringent than the MACT standards that are not
prohibitively expensive and are thus unreasonable. We noted our view
that this will allow States, in many cases, to conclude that the
control measures implemented to meet MACT standards satisfy any
requirement for VOC RACT.
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\43\ There are some MACT categories for which it may not be
possible to determine the degree of VOC reductions from the MACT
standard without additional analysis; for example, the miscellaneous
metal parts and products (40 CFR part 60, subpart MMMM) due to the
uncertainty of the compliance method that will be selected.
---------------------------------------------------------------------------
(3) Compliance With MACT Standards Affecting PM2.5
Emissions. Compliance with MACT standards may be considered in direct
PM2.5 RACT determinations. For direct PM2.5
sources subject to MACT standards, States may streamline their RACT
analysis by including a discussion of the MACT controls and relevant
factors such as whether PM2.5 emissions are well controlled
under the relevant MACT air toxics standard, which units at the
facility have MACT controls, and whether any major new developments in
technologies or costs have occurred subsequent to the MACT standards.
We believe that there are many direct PM2.5 sources that are
well controlled (e.g., through add-on controls that represent state-of-
the-art measures for PM2.5 reduction) because they are
regulated by the MACT standards which EPA developed under CAA section
112. For some MACT standards, PM2.5 is used as a surrogate
for achieving MACT for HAPs such as heavy metals. Any source subject to
MACT standards must meet a level that is as stringent as the best-
controlled 12 percent of sources in the industry. We believe that there
will be sources for which it will be unlikely that States will identify
emission controls more stringent than the MACT standards that are not
prohibitively expensive and are thus unreasonable. In addressing
whether a MACT standard represents best controls for PM2.5,
it is important that the State consider all PM2.5 sources at
a given facility and the nature of the PM limit (i.e., whether the
limit ensures control of the fine fraction of particulate matter).
Also, the State should evaluate the degree of capture of
PM2.5--that is, the amount of PM2.5 that is
collected and sent to a pollution control device in addition to the
efficiency of the device itself. This evaluation should consider the
PM2.5 emissions reductions that could be achieved by
improving the degree of capture.
(4) Year-Round Controls for NOX. In some cases, sources
subject to NOX RACT for PM will also be subject to controls
under the NOX SIP Call. In the 8-hour ozone implementation
rule, EPA concluded that certain sources which have installed emission
controls to comply with the NOX SIP call would be deemed to
meet NOX RACT for the purposes of the 8-hour ozone
implementation program. Some of these sources subject to the
NOX SIP call may choose to control NOX emissions
only or primarily during the ozone season. For purposes of
PM2.5, however, EPA concludes that the operation of emission
controls only or primarily during the ozone season would not constitute
RACT for PM2.5 purposes. Indeed PM2.5 control
programs must address annual average concentrations, and in many
[[Page 20631]]
areas nitrate concentrations are generally highest in the winter.
Therefore, RACT for PM2.5 is year-round operation of
controls. For sources subject to both the NOX SIP call and
NOX RACT for PM, we believe that, in most cases, the
additional costs of running the NOX SIP call controls year-
round would impose only modest, reasonable additional costs and the
cost effectiveness would be better than the average cost effectiveness
for many other sources subject to PM RACT. (See further discussion in
section F.7 above related to EGU sources subject to CAIR requirements
for NOX).
c. Comments and Responses
Comments: A number of commenters agreed with the requirement for
the State to conduct a new RACT determination for any source for which
the State's prior RACT analysis under another NAAQS program concluded
that RACT was defined as no additional controls. One commenter noted
that for a source having a previous RACT determination for ozone or
PM10 to show that its level of control currently meets RACT
for PM2.5 purposes, the source must provide supporting
documentation showing that the previous RACT determination was based on
the same universe of controls that are ``reasonably available'' for the
source in the present day.
Response: The EPA agrees with these comments.
Comments: A few commenters recommended that EPA clarify that RACT
determinations resulting only in ``operational changes'' should be
treated in an equivalent manner as those resulting in no controls. The
commenters suggested that, unlike ``physical modification,'' such
operational changes should always be revisited with a new RACT
determination.
Response: The EPA does not agree with the implicit recommendation
to impose different RACT review requirements based on the types of
control previously implemented. The EPA believes that a reassessment of
RACT is warranted, irrespective of the type of control previously
implemented, to consider the reasonableness of modifying or adding
controls in the particular circumstances. Furthermore, we are concerned
that making such a distinction based upon the fairly broad term
``operational change'' would be difficult to interpret and implement, and
would invite unnecessary disputes concerning the application of the term.
Comment: Commenters differed on whether new RACT determinations
should be required for all existing determinations made before a
specific date, and on what that date should be. Some commenters
recommended that EPA allow States to rely on any previous RACT
determinations made after 1990, and one commenter recommended that EPA
require States to review only those older than 10-15 years, another
recommended 10 years. One commenter believed that a 15-year period
would be reasonable where previous controls were installed, to allow
for a 15-year amortization of the cost of those controls. Other
commenters recommended that new RACT determinations be made for any
RACT determinations older than 5 years. Another commenter recommended
that all RACT determinations should be reviewed.
Response: The EPA has not included any specific time frame in the
final rule. The EPA agrees that the more recent the RACT determination,
the greater the probability that technology advances or decreases in
control cost will not have occurred. At the same time, technology
advances and decreases in control cost can and have occurred
frequently. Accordingly, we believe it is necessary for States to
review whether such technology advances or decreases in control cost
have occurred before relying on previous RACT determinations. We do not
believe there is any specific date or age that could be identified
after which States could ensure that no technology advances or
decreases in control cost will have occurred.
Comment: A number of commenters expressed concerns with the
resources required to conduct the certifications required by the
proposed approach, and argued that expending the resources required to
review and to certify previous RACT determinations would not be
productive. One commenter recommended that EPA provide guidance on the
previous RACT categories for which old RACT determinations are believed
to be out of date. Another commenter asserted that the only possible
exception to the acceptability of previous RACT measures for purposes
of the ozone standards would be when the new RACT is year-round for an
existing ozone-season RACT measure.
Response: The EPA believes that the proposed certification approach
strikes an appropriate balance in requiring States to verify whether
previous RACT determinations currently represent an appropriate RACT
level of control for PM2.5 purposes, while stopping short of
requiring an exhaustive re-analysis for all RACT sources. The EPA
believes that much of the resource concerns expressed in comments were
based upon concerns that VOC sources are very numerous, and that this
approach would require detailed review for these sources. As noted
previously, a RACT analysis for VOC sources is required only if a State
makes a finding that VOC sources significantly contribute to
nonattainment in the State. We believe the commenters likely
overestimate the resource implications of the certification process for
prior RACT determinations. Another mitigating factor is that many of
these same sources would be reviewed for purposes of implementing the
eight-hour ozone standard. On the other hand, where a State or EPA
determines that it is appropriate to regulate VOC sources for
PM2.5, EPA believes that it likely would be productive to
review the previous determination for such sources, some of which have
not been reviewed for many years.
Comment: One commenter believed that EPA should acknowledge
detailed RACT and RACM analyses for the South Coast and San Joaquin
Valley in California prepared during the 1990s for purposes of
implementing the ozone and PM10 standards. The commenter
believes that EPA acceptance of these determinations as RACT for
PM2.5 would enable States to focus resources on developing
new measures needed for attainment.
Response: The EPA agrees that States should focus resources on new
technologies and new developments. At the same time, EPA recognizes
that for most source categories, new technology continues to be
developed, and new information continues to be generated. Thus, even
recent RACT determinations for a given source category may be outdated.
Hence, the certification approach in the rule for the relevant sources
or source categories is a reasonable approach which is designed to
provide for the type of focused efforts suggested by the commenter.
Comment: One commenter believed that a State certification should
only have to identify the existing RACT levels in a SIP and pollutants
affected, but the State should not be required to provide any
additional information.
Response: The EPA disagrees with this comment. The EPA believes
that prior technology determinations should be taken into account in
the RACT determination process. In reviewing existing RACT
determinations, the State should provide supporting information to show
that the existing technology in use should still be considered RACT, or
it should show that there have been technology advances or cost
reductions that have occurred since the previous
[[Page 20632]]
RACT limits were developed that make lower emissions technically and
economically feasible in the context of RACT and would contribute to
advancing the attainment date by at least one year.
Comment: Some commenters supported EPA's requirement for year-round
operation of NOX pollution control devices as RACT, given
that PM2.5 is an annual standard, while ozone is a
summertime problem.
Response: The EPA agrees with these comments.
Comment: One commenter concluded that BACT and LAER determinations
should be considered to satisfy RACT, regardless of the date they were
made, because BACT and LAER by definition are more stringent than RACT.
Response: The EPA disagrees with this comment. The EPA believes
that in many cases, but not all, BACT and LAER would assure RACT level
of controls. Reasons that BACT and LAER might not satisfy RACT include:
The pollutant of concern could have been different, the applicability
threshold for BACT and LAER may have excluded smaller sources
potentially subject to RACT controls, and technology advances or
reductions in control costs may have occurred since the old
determination was conducted.
Comment: One commenter recommended that EPA allow States to use
information gathered from prior BACT or LAER analyses to complete the
RACT determination, as was allowed in the 8-hour ozone NAAQS
implementation rule.
Response: The final rule allows for use of such information, to the
extent it remains valid, to inform a certification by the State that
BACT or LAER technology continues to exceed what would currently be
considered RACT.
Comment: Some commenters argued that any MACT determination that
controls the pollutants of concern should be more than sufficient to
satisfy RACT. Some commenters made similar recommendations regarding
specific standards where PM limits were developed as a surrogate for
HAPs, such as the MACT standard for integrated iron and steel mills,
the MACT standard for iron and steel foundries, and the section 129
standards for waste to energy facilities.
Response: While agreeing that MACT controls are relevant, the EPA
disagrees that all MACT determinations should be automatically
considered to satisfy RACT. Reasons include: A MACT standard aimed at
toxics might not ensure that the relevant PM2.5 pollutant(s)
are well controlled, MACT applicability provisions might have excluded
units potentially subject to RACT, and technology advances or
reductions in control costs might have occurred since EPA conducted the
MACT analysis. The EPA believes that the State should review whether
technology advances have occurred including available ``beyond the MACT
floor'' technologies that may be reasonable in the context of RACT for
PM2.5 nonattainment, but which were not selected as MACT for
purposes of implementing section 112. The EPA believes that RACT
analyses should evaluate whether increased capture of PM2.5
could be achieved, and whether an increased efficiency in controlling
the fine fraction of particulate matter is reasonably available. The
EPA has, however, added a specific recognition that MACT standards can
reduce PM2.5 as well as VOC, and that PM2.5
information gathered for MACT standards development may inform a State's
conclusions on available technologies for direct PM2.5 emissions.
Comment: One commenter expressed a concern that EPA should not
presume that MACT represents RACT where the MACT rule allows for a
risk-based exemption from the control technology requirement.
Response: The EPA agrees with this comment.
11. How Should Condensable Emissions Be Treated in RACT Determinations?
a. Background
Certain commercial or industrial activities involving high
temperature processes (fuel combustion, metal processing, cooking
operations, etc.) emit gaseous pollutants into the ambient air which
rapidly condense into particle form. The constituents of these
condensed particles include, but are not limited to, organic material,
sulfuric acid, and metals. In general, condensable emissions are taken
into account wherever possible in emission factors used to develop
national emission inventories, and States are required under the
consolidated emissions reporting rule (CERR) \44\ to report condensable
emissions in each inventory revision. Currently, some States have
regulations requiring sources to quantify condensable emissions and to
implement control measures for them, and others do not. In 1990, EPA
promulgated Method 202 in Appendix M of 40 CFR Part 51 to quantify
condensable particulate matter emissions. In the proposed rule, EPA
discussed and requested comment on issues related to condensable
emissions in RACT determinations.
---------------------------------------------------------------------------
\44\ The consolidated emissions reporting rule was published in
the Federal Register on June 10, 2002, pages 39602-39616.
---------------------------------------------------------------------------
In the proposed rule, we noted that EPA is in the process of
developing detailed guidance on a new test method which quantifies and
can be used to characterize the constituents of the PM2.5
emissions including both the filterable and condensable portion of the
emissions stream. We also noted that when a source implements either of
these test methods addressing condensable emissions, the State will
likely need to revise the source's emissions limit to account for those
emissions that were previously unregulated. For the purposes of
determining RACT applicability and establishing RACT emission limits,
EPA indicated in the proposal that it intends to require the State to
adopt the new test method once EPA issues its detailed guidance. This
guidance would be for use by all sources within a PM2.5
nonattainment area that are required to reduce emissions as part of the
area's attainment strategy.
b. Final Rule
Issues and comments related to test method and emissions limit
issues for direct PM2.5 for RACT, including discussion of
test methods for condensable PM2.5, are discussed in section
II.L.3 of this preamble. The EPA recognizes that in some cases
condensable emissions are more difficult to control than filterable
emissions. However, condensable emissions may be assumed to be almost
entirely in the 2.5 micrometer range and smaller, so these emissions
are inherently more significant for PM2.5 than for prior
particulate matter standards addressing larger particles. Therefore,
EPA encourages States to consider the potential for reducing
condensable emissions when evaluating potential measures for RACT.
12. What Criteria Should Be Met To Ensure Effective Regulations To
Implement RACT and RACM?
a. Final Rule
After the State has identified a RACT or RACM measure for a
particular nonattainment area, it must then implement that measure
through a legally enforceable mechanism (e.g., a State rule approved
into the SIP). The legally enforceable mechanism must meet four
important criteria.
First, the baseline emissions from the source or group of sources
and the future year projected emissions must be quantifiable so that
the projected emissions reductions from the sources can be attributed
to the specific
[[Page 20633]]
measures being implemented. It is important that the emissions from the
source category in question are accurately represented in the baseline
inventory so that emissions reductions are properly calculated. In
particular, it is especially important to ensure that both the
filterable and condensable components of PM2.5 are
accurately represented in the baseline since traditional Federal and
State test methods have not included the condensable component of
particulate matter emissions and have not required particle sizing of
the filterable component.
Second, the control measures must be enforceable. This means that
they must specify clear, unambiguous, and measurable requirements. When
feasible, the measurable requirements for larger emitting facilities
should include periodic source testing to establish the capability of
such facilities to achieve the required emission level. Additionally,
to verify the continued performance of the control measure, specific
monitoring programs appropriate for the type of control measure
employed and the level of emissions must be included to verify the
continued performance of the control measure. The control measures and
monitoring program must also have been adopted according to proper
legal procedures.
Third, the measures must be replicable. This means that where a
rule contains procedures for interpreting, changing, or determining
compliance with the rule, the procedures are sufficiently specific and
nonsubjective so that two independent entities applying the procedures
would obtain the same result.
Fourth, the control measures must be accountable. This means, for
example, that source-specific emission limits must be permanent and
must reflect the assumptions used in the SIP demonstration. It also
means that the SIP must establish requirements to track emission
changes at sources and provide for corrective action if emissions
reductions are not achieved according to the plan.
b. Comments and Responses
There were no comments on this section. The language above is very
similar to the language in the proposal.
G. Reasonable Further Progress (RFP)
1. Background
Clean Air Act Section 172(c)(2) requires that plans for
nonattainment areas ``shall require reasonable further progress,''
which as defined in Section 171(1) ``means such annual incremental
reductions in emissions of the relevant air pollutant as are required
by this part or may reasonably be required by the Administrator for the
purpose of ensuring attainment of the applicable national ambient air
quality standard by the applicable date.'' This section describes the
requirements the Administrator is establishing for states to achieve
reasonable further progress.
In general terms, the goal of these RFP requirements is for areas
to achieve generally linear progress toward attainment. The RFP
requirements were included in the Clean Air Act to assure steady
progress toward attaining air quality standards, as opposed to
deferring implementation of all measures until the end date by which
the standard is to be attained.
2. Requirements for Areas With Attainment Dates of 2010 or Earlier
a. Background
In 40 CFR 51.1009(b)(1) of the proposed rule, EPA proposed that a
State which submits an implementation plan that demonstrates that an
area will achieve attainment by 2010 (i.e., achieves attainment level
emissions during 2009) would not be required to submit a separate
reasonable further progress plan for that area. In such cases, EPA
proposed that the attainment demonstration would also be considered to
demonstrate that the area is achieving RFP.
b. Final Rule
In the final rule, EPA is maintaining the approach described in the
proposed rule. An area that demonstrates attainment by 2010 will be
considered to have satisfied the RFP requirement and need not submit
any additional material to satisfy the RFP requirement. The EPA will
view the attainment demonstration as also demonstrating that the area
is making reasonable further progress toward attainment.
c. Comments and Responses
Comment: A number of commenters supported EPA's view that a
demonstration of attainment by 2010 would also demonstrate that the
area is making reasonable further progress toward attainment.
Response: The EPA appreciates the support and is adopting the
supported approach.
Comment: A set of commenters objects to EPA's proposal, arguing
that EPA cannot waive RFP requirements for areas where the state
purports to demonstrate attainment. These commenters believe that
Subpart 4 of Part D requires milestones prior to 2009, and these
commenters believe that even Subpart 1 requires a demonstration of
interim progress that EPA cannot waive.
Response: In brief, EPA is not waiving the RFP requirements for any
area. Instead, EPA is concluding that a demonstration of attainment by
2010 also serves to demonstrate achievement of RFP. If the state
submittal purports to demonstrate attainment but does not adequately
make this demonstration, then the submittal also would not demonstrate
achievement of RFP. The nature of the RFP requirement would then depend
on whether the remedied attainment demonstration provides for
attainment by 2010. Finally, as discussed above, EPA believes that
Subpart 4 requirements do not apply to PM2.5 plans. More
detailed discussion of this comment and EPA's response are provided in
the response to comments document.
3. Requirements for Areas With Attainment Dates Beyond 2010
a. Background
The proposed rule required a State to submit an RFP plan along with
its attainment demonstration and SIP due in April 2008 for any area for
which the State demonstrates that 2011 or later is the most expeditious
attainment date. EPA proposed that the 2008 RFP plan must provide
adequate emission reductions by 2009 \45\ and, in some cases, by 2012.
The plan must demonstrate that emissions will decline in a manner that
represents generally linear progress from the 2002 baseline year to the
attainment year.
---------------------------------------------------------------------------
\45\ The RFP test uses inventories for the full year, e.g. the
year of 2009 or the year of 2012. EPA does not specifically require
that the relevant measures be implemented by the beginning of the
year, but RFP inventories must reflect the fact that measures that
are implemented later in the year have correspondingly less impact
on the year's annual total emissions.
---------------------------------------------------------------------------
b. Final Rule
The final rule requires a State to submit an RFP plan along with
its attainment demonstration and SIP due in April 2008 for any area for
which the State justifies an extension of the attainment date beyond
2010. The RFP plan must provide emission reductions such that emissions
in 2009 represent generally linear progress from the 2002 baseline year
to the attainment year. Where the State justifies an extension of the
attainment deadline to 2014 or 2015, the state must additionally provide
emission reductions such that emissions in 2012 represent generally
linear progress from the 2002 baseline year to the attainment year.
[[Page 20634]]
If the State demonstrates that attainment will occur by 2010 or
earlier, EPA will consider the attainment demonstration to demonstrate
achievement of reasonable further progress, and the State will not be
required to submit an additional RFP plan for the area.
c. Comments and Responses
Comment: For areas that demonstrate attainment by 2015 without
adopting additional measures, a commenter recommended that the
attainment demonstration be viewed as also demonstrating that the area
is achieving RFP. The commenter therefore recommended that the state
not be required to submit an RFP plan for such an area.
Response: A submittal that demonstrates attainment at the latest
allowable date and does not address interim air quality fails to show
that the path to attainment will yield interim incremental air quality
improvements. States have ample opportunity to adopt measures that
would provide interim air quality improvement long before 2015. Indeed,
as discussed elsewhere as part of the discussion of attainment dates, a
submittal that only addresses 2015 would also fail the attainment
demonstration requirement, insofar as it would not be addressing
whether attainment is as expeditious as practicable, because the
submittal would fail to assess whether attainment could be achieved
earlier. Therefore, irrespective of whether additional measures are
needed to attain by 2015, the Clean Air Act mandates assessing progress
at reasonable interim dates as well as mandating attainment.
4. Generally Linear Progress and Associated Timeline
a. Background
The EPA proposed that states with areas needing an extension of the
attainment deadline beyond 2010 would be required to submit a plan
demonstrating that emissions would be sufficiently reduced by 2009 to
achieve a generally linear incremental improvement in air quality. The
notice of proposed rulemaking provided an example calculation for an
area with a 2013 attainment date, i.e. an area that achieves attainment
level emissions in 2012. (See section III.G.4.b.iv of the proposal, 70
FR 66013.) In this example, the 2009 emissions year represents 7/10 of
the period extending from the baseline year of 2002 to the 2012 year of
attainment level emissions. Therefore, for this example, EPA's proposed
requirement would be for this area to achieve emission reductions by
2009 representing approximately 7/10 of the emission reductions needed
to attain the standards. For states with areas needing the attainment
deadline extended to 2014 or 2015, EPA proposed to require achievement
of generally linear emission reductions at two RFP milestone years--the
2009 and 2012 emission years.
The EPA received several comments on various elements of its
proposed approach. Several commenters objected to EPA's proposed
requirement to achieve linear progress toward attainment, asserting
that EPA cannot reasonably expect states to achieve a significant
amount of progress within a short time after plan submittals are due.
Some commenters recommended requiring a specific emission reduction
percentage, similar to the rate of progress requirement for ozone.
These comments are addressed below.
b. Final Rule
The EPA is requiring States with areas needing an extension of the
attainment deadline to submit RFP plans. These plans must demonstrate
that generally linear reductions in emissions will occur by 2009, i.e.
that emissions in 2009 will be reduced to the extent represented by a
generally linear progression from 2002 base year emissions to
attainment-level emissions. For any area that needs an extension of the
attainment deadline to 2014 or 2015, the State's RFP plan would also
need to demonstrate that generally linear reductions will be achieved
in the 2012 emissions year as well.
c. Comments and Responses
Comment: Several commenters objected to EPA's proposed requirement
that states demonstrate linear progress toward attainment. For example,
a commenter stated that a ``generally linear reduction process may not
be practicable.'' A commenter stated that it ``agrees that areas should
be able to take credit for reductions from 2002 forward, [but] EPA
should allow for fewer reductions (as opposed to linear reductions)
prior to 2008.''
A commenter noted that EPA's ``proposed approach ignores several
important realities about PM NAAQS implementation. First, * * * [n]ot
until SIP submittal in April 2008, some 6 years after the RFP baseline
date, will any local measures be finally adopted and approved. Under
[the example EPA provided in its proposed rulemaking], states will be
required to play `catch-up' by achieving 70 percent of the required
reductions in 2009. * * * Second, the `generally linear' approach
ignores that EPA intends for states to rely in large part on mobile
source reductions and reductions in NOX and SO2
from CAIR implementation to achieve attainment in many areas. These
measures fail a `generally linear' test since most of the reductions
they provide will not be realized until after 2009.'' This commenter
continues that the incremental reductions in emissions required in the
Clean Air Act need not be equal increments, that the absence of a
specific statutorily mandated increment (such as the 3 percent per year
requirement for ozone) allows EPA to be more flexible and to rely more
heavily on later reductions. The commenter also argues that EPA's
proposal is more stringent than the ozone RFP requirement, insofar as
the ozone RFP requirement provides for averaging over 3 years. Similar
comments were submitted by other commenters.
Another commenter supported EPA's proposal. This commenter
supported requiring demonstrations that areas achieve emission
reductions that will yield incremental improvement in air quality on a
path toward expeditious attainment.
Response: The EPA believes that the requirement for generally
linear reductions is reasonable because it allows States to take credit
for early reductions achieved due to federal, State, and local
programs. We find that it appropriately implements the RFP requirement
in the Clean Air Act. For these reasons, EPA is finalizing the
requirement that RFP plans for areas needing an attainment deadline
extension show generally linear progress in reducing emissions from the
base year through the 2009 emissions year. EPA is also requiring that
areas needing an attainment deadline extension to 2014 or 2015 (i.e.
attainment level emissions projected to start in 2013 or 2014) show
generally linear progress in reducing emissions through the 2012
emissions year.
The commenters objecting to the requirement for generally linear
progress appear to be assuming that only minimal emission reductions
can be expected before 2008, so that a requirement for generally linear
progress would require plans submitted in 2008 to compensate by
achieving unrealistically high levels of emission reductions. The EPA
disagrees with this assumption.
In fact, substantial emission reductions have occurred in the past
few years and can be expected to occur through the 2009 emissions year.
The EPA has promulgated significant mobile source rules recently that
will yield
[[Page 20635]]
substantial benefits in the coming years, and these benefits follow a
series of prior rules that provide a steady progression of emission
reductions as newer, cleaner vehicles replace older, dirtier vehicles.
For utilities, significant NOX reductions occurred in 2004
under the NOX SIP call, and substantial SO2
reductions are expected to occur under the CAIR trading program prior
to 2010 due to incentives for early reductions and the banking of
allowances.
The EPA has also promulgated many other regulations that will
reduce particulate matter and particulate matter precursor emissions
before as well as after 2009. States have also been implementing a
variety of measures. With use of a 2002 baseline, the assessment of RFP
allows credit for these measures. The following is a partial list of
the measures that have been adopted and will contribute to achieving
generally linear reductions:
? NOX SIP Call.
? Tightened emission limits for new gasoline and diesel vehicles.
? Numerous regulations requiring Maximum Achievable Control
Technology, including regulations for:
--Iron and steel plants, including coke plants
--Industrial boilers
--Cement plants
--Lime plants
--Primary aluminum plants
? Numerous consent decrees for refineries.
? Numerous consent decrees for power plants.
? The Clean Air Interstate Rule for utilities.
? Retrofitted controls on diesel vehicles, and related
programs for reducing diesel vehicle emissions.
? Closures of coke plants and other facilities (and, from a
national perspective, replacement with cleaner new facilities).
While different control measures require various timelines for
implementation, EPA believes that many of the additional measures that
states might adopt for attainment planning purposes can be implemented
in a timely fashion for addressing RFP requirements. Thus, EPA believes
that states can reasonably be expected to assure that the combination
of existing measures and additional measures as necessary will provide
for generally linear progress in reducing emissions. Furthermore,
particularly with respect to the 2009 RFP milestone year, when EPA
evaluates whether the emission levels in a state plan represent
generally linear progress, EPA will consider the availability of
measures that can be implemented by 2009.
It is difficult to compare the stringency of this RFP requirement
to the RFP requirement for ozone. The RFP requirement for ozone
measures one form of progress that occurs after 3 years, and the
requirement for PM2.5 measures a different form of progress
that occurs after 7 years (and for some areas also after 10 years).
That is, the ozone RFP requirement applies a fixed, universally
applicable emission reduction percentage for one pollutant (VOC),
whereas EPA is defining the PM2.5 RFP requirement as an
area-specific combination of emission reductions for multiple
pollutants, defined on the basis of each area's attainment demonstration.
The EPA believes that the Clean Air Act mandates not merely
eventual attainment by 2015 but also that states demonstrate that
emissions are being incrementally reduced in earlier years. (As
discussed elsewhere, states must also demonstrate attainment by earlier
than 2015 if feasible.) The requirement for RFP reflects Congressional
intent that areas make steady progress toward attainment in the years
before attainment occurs, and states have ample opportunity to assure
that reductions occur well before 2015.
Comment: A commenter observes that the PM2.5
nonattainment areas in its state also violate the ozone standard. The
commenter observes, ``[i]n setting plan requirements, U.S. EPA should
choose options that best facilitate harmonization of fine particulate
and ozone control programs. This includes using a fixed percentage of
emission reductions per year for reasonable further progress (RFP). We
recommend the ozone RFP metric of three percent annual emission
reductions averaged over three years.'' Another commenter also supports
a more prescriptive RFP requirement, and comments that ``As suggested
by EPA, nonattainment areas must be required to achieve `a fixed
percentage reduction of the emissions of direct PM2.5 and
regulated PM2.5 precursors and in specific milestone years'
between the base year and the attainment year proposed in the
attainment demonstration.'' A third commenter supported establishing a
requirement for a fixed emission reduction percentage, set at ``no less
than the 3 percent rate'' in Section 182, with the possibility of
higher rates in areas with more severe air quality problems.
Other commenters prefer the approach that EPA proposed. For example
one commenter states that it agrees with EPA's approach of using the
attainment demonstration to define the parameters for determining what
constitutes RFP, and the commenter supports the flexibility of EPA's
proposed approach ``rather than requiring fixed linear percentage
reductions.'' Regarding the proposed option to require 3 percent per
year emission reductions for areas classified as serious, some
commenters recommended against establishing classifications and a fixed
emission reduction percentage for any area.
Response: Requiring a fixed annual emission reduction percentage
would impose a ``one-size-fits-all'' approach to address a range of
circumstances. Requiring a fixed annual emission reduction percentage
would overstate the reductions needed to achieve timely attainment in
some areas and would understate the reductions needed to achieve timely
attainment in other areas. The EPA believes that defining the RFP
requirement in terms of achieving generally linear progress toward the
emission reductions needed for timely attainment assures that each area
will achieve a steady rate of progress most appropriate for the area to
achieve timely attainment.
The EPA recognizes that many areas are nonattainment for both
PM2.5 and ozone and that the control programs for the two
pollutants are sufficiently intertwined that harmonization of planning
for meeting requirements applicable to the two pollutants is important.
However, because the statutory requirements set forth in section 182 do
not apply to PM2.5 RFP plans, EPA believes it is neither
necessary nor appropriate to impose these requirements for
PM2.5. Indeed, given the multiple pollutants that contribute
to PM2.5 and the variations that exist in the nature and
composition of PM2.5 across the country, EPA believes that
the PM2.5 RFP requirements for generally linear reductions
are better defined to reflect these variations and thus better targeted
toward the emission reductions that in each area can be expected to
lead toward timely attainment. Further, EPA believes that application
of a different form of the RFP requirement does not cause conflicts in
implementation planning for the two standards. For example, reductions
of NOX emissions will generally reduce concentrations of
both ozone and PM2.5, and NOX emission reductions are
creditable for meeting both the ozone and the PM2.5 RFP requirements.
An important distinction between PM2.5 and ozone is that
fine particle formation is in general a more complex process, affected
by both direct emissions and numerous precursor pollutants. The EPA
does not believe
[[Page 20636]]
that RFP targets for PM2.5 should be the same as those used
for the ozone implementation program, nor should the same percentage
reduction be used for all PM2.5 related pollutants. Instead,
EPA believes that RFP plans should reflect an appropriate combination
of pollutant reductions that most effectively provides for attainment.
Therefore, EPA has defined an RFP requirement in which target emission
reductions are established in conjunction with the area's attainment plan.
5. Geographic Coverage of Emissions Sources
a. Background
PM2.5 concentrations reflect a combination of impacts
over a wide range of geographic scales. For some components of
PM2.5, observed concentrations typically arise predominantly
from sources within the nonattainment area. For other components,
PM2.5 concentrations may be influenced by sources across a
broad area extending outside the nonattainment area. The EPA's intent
is to define the RFP requirement in terms of emissions reductions that
can be expected to provide generally linear improvements in air quality
in the nonattainment area. For this purpose, EPA continues to believe
that RFP requirements for PM2.5 are best defined such that
states evaluate emissions of each pollutant throughout the area in
which the emissions substantially influence PM2.5
concentrations in the nonattainment area.
As described in the proposed rulemaking, EPA expects each area's
attainment demonstration to identify many of the parameters used to
define the emission reductions that would represent RFP. First, the
attainment plan will identify the pollutants that are being reduced to
achieve attainment. Second, the attainment plan will identify the
amount of reduction of each pollutant and the date by which attainment
can be achieved. This information suffices to calculate a baseline set
of reductions to be achieved by 2009 to provide for RFP. Third, where a
state chooses to achieve RFP by reducing some pollutants earlier than
others, the attainment plan will provide the information needed to
assess whether the intended set of reductions can be expected to
provide a comparable level of air quality improvement. Fourth, if the
State intends to include emissions sources located outside the
nonattainment area in its RFP plan, the information necessary to justify
inclusion of such sources will likely be found in the attainment plan.
The EPA's proposed rulemaking identified several expectations
regarding regional versus local impacts. For directly emitted
PM2.5 (including organic and other carbonaceous particles as
well as miscellaneous inorganic particles and including condensable
particulate matter), EPA recognized that impacts are commonly
localized, and that direct emissions of PM2.5 outside the
nonattainment area should not be included in the RFP plan. Conversely,
EPA recognized the regional nature of secondarily-formed sulfate and
nitrate, and proposed that states could justify inclusion in the RFP
plan of SO2 and NOX emissions sources located
within 200 kilometers of the nonattainment area.
The EPA recognizes that fine particles travel over long distances,
and that distant emissions of SO2 and NOX
emissions can influence a nonattainment area's air quality. At the same
time, distant sources can be expected to have less impact than sources
closer to the nonattainment area. EPA's procedures for assessing RFP
rely on a general assumption that all the sources included in the
assessment have a comparable impact per ton of emissions. For this
reason, it would be inappropriate to include distant emission sources
in the assessment. Indeed, limiting the consideration of SO2 and NOX
emissions to a 200 kilometer range is intended to assure that only sources
with comparable impacts are included in the assessment.
b. Final Policy
The policy for addressing direct PM2.5 emissions in RFP
plans remains unchanged from the proposal: only emissions from within
the nonattainment area may be included. Conversely, for SO2
and NOX, EPA believes that states could be able to justify
considering not only all emissions in the nonattainment area but also
emissions within a distance that may be up to 200 kilometers from the
nonattainment area. States may also be able to justify consideration of
VOC and ammonia emissions outside the nonattainment area on a case-by-
case basis. As we explain more fully below in responding to comments,
in situations where the state demonstrates that VOCs are a significant
contributor to PM2.5 concentrations in the area, it may be
appropriate to include VOC emission sources within a distance of up to
100 kilometers of the nonattainment area. Given the uncertainties
regarding ammonia emission inventories and the effects of reducing
ammonia, EPA is not establishing a policy on this issue with respect to
ammonia. States that expect to regulate ammonia should consult with
their regional offices to determine appropriate approaches for those
areas. The justification for considering emissions outside the
nonattainment area shall include justification of the state's
recommended definition of the area used in the RFP plan for each pollutant.
The EPA received comments objecting to the possibility that RFP
inventories for areas outside the nonattainment area could include
selected sources expecting substantial emission reductions while
excluding other nearby sources expecting emission increases. Based on
its review of these comments, EPA is revising its approach for
considering regional emissions. If the state justifies consideration of
precursor emissions for an area outside the nonattainment area, EPA
will expect state RFP assessments to reflect emissions changes from all
sources in this area. The State cannot include only selected sources
providing emission reductions in the analysis. The inventories for
2002, 2009, 2012 (where applicable) and the attainment year would all
reflect the same source domain (i.e. the same set of sources except for
the addition of any known new sources or removal of known, creditably
and permanently shut down sources).
In cases where the state justifies consideration of emissions of
specified precursors from outside the nonattainment area, the state
must provide separate information regarding on-road mobile source
emissions within the nonattainment area for transportation conformity
purposes. The EPA's transportation conformity regulations (40 CFR Part
93.102(b)) only require conformity determinations in nonattainment and
maintenance areas, and these regulations rely on SIP on-road motor
vehicle emission budgets that address the designated boundary of the
nonattainment area. For this reason, if the state addresses emissions
outside the nonattainment area for a pertinent precursor (i.e. a
precursor for which mobile sources are significant, as discussed in the
May 6, 2005 transportation conformity rule on PM2.5
precursors at 72 FR 24280), the on-road mobile source component of the
RFP inventory will not satisfy the requirements for establishing a SIP
budget for transportation conformity purposes.
In such a case, the state must supplement the RFP inventory with an
[[Page 20637]]
inventory of onroad mobile source emissions to be used to establish a
motor vehicle emissions budget for transportation conformity purposes.
This inventory must address on-road motor vehicle emissions that occur
within the designated nonattainment area, must be provided for the same
milestone year or years as the RFP demonstration (i.e. 2009 and 2012 as
applicable), and must satisfy other applicable requirements of the
transportation conformity regulations. So long as the state provides
this separate emissions budget EPA believes that this approach will
optimally address both the RFP and the transportation conformity
provisions of the Act.
The EPA is restricting the geographic area for RFP assessments to
include only areas within the state or states represented in the
nonattainment area. For a single state nonattainment area, only
emissions within that state would be considered, even if other states
may be within 200 kilometers of the nonattainment area. For multi-state
nonattainment areas, only regions within states represented in the
nonattainment area shall be included in the RFP assessment. This
restriction is intended to address commenters' concerns about the
enforceability of emission reductions included in the RFP assessment
and helps assure accountability for these reductions. This topic is
discussed further in the discussion below about multi-state
nonattainment areas.
The EPA is retaining the approach that RFP assessments may not
include direct PM2.5 emissions from sources outside the
nonattainment area. If a State regulates VOC or ammonia emissions as
part of its attainment strategy, the RFP plan must include emissions of
these pollutants. In the event that a State technical demonstration
indicates that emissions of VOC or ammonia from sources outside the
nonattainment area contribute significantly to PM2.5
concentrations in the nonattainment area, EPA will consider on a case-
by-case basis whether it would be appropriate to include emissions from
such sources in the RFP plan.
c. Comments and Responses
The EPA received numerous comments on its proposal regarding how
regional versus local impacts would be addressed. Multiple commenters
objected to EPA's proposal that states could consider sources reducing
emissions but ignore neighboring sources increasing emissions. Other
commenters recommended that EPA support granting credit for reductions
of direct PM2.5 emissions that occur outside nonattainment
areas. A few commenters also recommended different treatment of
selected pollutants.
Comment: Several commenters object to the methods by which EPA
proposed to account for reductions outside the nonattainment area.
According to a set of commenters, if indeed sources outside the
nonattainment area contribute to nonattainment, ``then EPA cannot
lawfully or rationally allow the state to claim RFP credit from a
single source's reductions without including in the baseline emissions
from all sources (mobile, area and stationary) within the same distance
from the nonattainment area, and without calculating the impacts of
increases and decreases in such emissions on RFP. Viewing reductions
from a single `outside the area' source in isolation will invariably
provide an incomplete and inaccurate picture of the actual increase or
decrease in emissions contribution to the nonattainment area from all
`outside the area' sources. Moreover, EPA's proposal creates numerous
opportunities to game and undermine the system. By allowing
nonattainment areas to rely on RFP reductions made outside the
nonattainment area, the proposed rule strays from the Act's focus on
achieving emissions reductions from sources within the nonattainment
area.'' Another commenter insisted that states should not be allowed to
consider emissions from sources outside the area unless they can demonstrate
the impacts of these sources on nonattainment area concentrations.
In addition, a commenter objects to consideration only of sources
that are reducing emissions and recommends that EPA allow credit for
upwind source reductions only ``on the condition that all other major
sources in the 200 kilometer boundary are also not allowed to increase
emissions.'' Another commenter supports an option which states would
only consider emissions within the nonattainment area, observing that
to consider emissions outside the nonattainment area would be difficult
to administer and might inappropriately ``dilute the reductions needed
in the nonattainment area.'' This commenter also observes that a 200
kilometer limit does not include much of the emissions that yield long
range transport. Another commenter supports crediting reductions
outside the nonattainment area but requests that EPA define the area to
be considered.
Response: The EPA agrees that examining emissions reductions of
only selected sources outside the nonattainment area gives an
inaccurate assessment of the progress that an area is making. For
example, if a state took credit for emission reductions at Source A but
ignored equal emission increases at neighboring Source B, the state
would claim emission reductions in its RFP plan when in fact no net
emission reductions had occurred.
The commenters suggest various remedies for this problem. One
suggestion is to include all sources within the area that is used.
Another suggestion is to allow no consideration of emissions outside
the nonattainment area. Yet another suggestion is to allow
consideration of selected sources so long as other sources do not
increase emissions.
The EPA is adopting the first of these suggestions: for the
pertinent area outside the nonattainment area, the RFP assessment must
include emissions (for all years evaluated) for all sources. The EPA
believes that inclusion of all sources is needed to ensure that the RFP
plan reflects the actual net emissions changes that are occurring in
the relevant area.
In cases where the state justifies consideration of emissions of
specified precursors from outside the nonattainment area, EPA is
accepting the recommendation of various commenters that the inventories
of these precursors used for RFP purposes shall include mobile source
emissions as well as stationary and area source emissions. However, in
cases where onroad mobile source emissions are significant and are
therefore included, the state would need to submit additional
information for transportation conformity purposes. As discussed above,
in accordance with existing transportation conformity regulations (40
CFR Part 93), the SIP's motor vehicle emissions budget(s) must reflect
an emissions inventory of on-road mobile source emissions for the
nonattainment area. Consequently, in these cases, the state would need
to supplement its RFP inventory with information identifying the
inventory of on-road mobile source emissions within the nonattainment
area for the pertinent precursor(s) for the applicable year or years
(i.e. 2009 and potentially 2012) to be used to establish a motor
vehicle emissions budget for transportation conformity purposes.
The relevant comments in general did not address the dimensions of
spatial domain of the sources outside the nonattainment area that would
be used in assessing RFP. EPA agrees with a commenter urging, as a
prerequisite to including sources of the pertinent pollutants outside
the nonattainment
[[Page 20638]]
area in the assessment, that states must justify the inclusion of
sources outside the nonattainment area. This justification would need
to demonstrate that these emissions have a substantial impact on
nonattainment concentrations that warrants including these emissions
along with nonattainment area emissions in assessing RFP. Another
commenter recommends that EPA define the area to be included. Since the
demonstrations of impact are best done by states, in conjunction with
their attainment planning, EPA intends to allow States to justify the
area to be included, within distance limits discussed above.
Comment: Numerous commenters recommend that EPA allow credit for
reductions of direct PM2.5 emissions outside the
nonattainment area. Some of these commenters also recommend that EPA
allow credit for mobile source emission reductions outside the
nonattainment area. Other commenters support EPA's proposed approach,
in which states may justify considering precursor emissions outside the
nonattainment area but must evaluate direct PM2.5 emissions
based solely on emissions within the nonattainment area.
Response: Under Section 107 of the Clean Air Act, EPA is to
designate nonattainment areas that include areas nearby to the
violations that contribute to the violations. Given the spatial scale
of the impacts of direct PM2.5 emissions, EPA believes that
any direct PM2.5 emission source that demonstrably
influences nonattainment area violations (and thus would contribute to
these violations) would also be considered to be nearby to the
violations for designation purposes. The EPA believes that it has
properly defined the nonattainment areas to include all nearby
contributing sources. Nevertheless, EPA asks anyone with evidence that
an additional source or source area contributes to violations in a
nonattainment area to submit that information to EPA and to recommend
incorporation of that source or source area into the nonattainment area.
The EPA has commented on consideration of mobile source emissions
above. For direct PM2.5 emissions, EPA believes that the
nonattainment area properly defines the area of consideration, and
emissions from mobile sources outside the nonattainment area, like
emissions from stationary sources outside the nonattainment area,
should not be considered. For precursors for which consideration of
emissions outside the nonattainment area is justified, the applicable
inventories would include emissions from all sources including mobile
sources as well as stationary sources.
Comment: A commenter states that ``RFP credits for VOC should be
granted for reductions achieved within the nonattainment area as well
as [within] geographical limits outside of the nonattainment area.''
This commenter supports consistency with the ozone policy, which allows
credit for NOX reductions within 200 kilometers and VOC
reductions within 100 kilometers of the nonattainment area. Another
commenter makes similar comments regarding VOC and comments that ``[a]s
the science and understanding of PM2.5 formation increases,
EPA must revisit the 200 kilometer parameter and develop a possible
proposal for ammonia.''
Response: Conceptually, EPA agrees that in areas where
anthropogenic VOC emissions outside the nonattainment area are shown to
be a significant contributor to nonattainment area PM2.5
concentrations, presumably by formation of organic particles that
influence nonattainment area concentrations, reduction of these VOC
emissions could help improve air quality in the nonattainment area.
Therefore, EPA is revising its policy to accommodate consideration of
these potential impacts. The EPA believes that as the impacts of
anthropogenic VOC on PM2.5 concentrations are better
understood, it may in some cases be appropriate to consider sources
outside the nonattainment area in RFP plans if the impacts from such
sources can be properly quantified and justified.
Nevertheless, EPA must highlight the technical challenges involved
in assessing the impacts of VOC emission reductions. First, it is
essential that the impacts of secondary organic particle formation from
anthropogenic VOC emissions be differentiated from the impacts caused
by biogenic VOC emissions and from the impacts of direct organic
particle emissions. Second, the process of organic particle formation
is highly complex, and currently available atmospheric models typically
perform poorly in assessing the mass of particles thus formed. Third,
the distance range of impacts, and to be more precise the distance
range over which source impacts are comparable, is especially
uncertain. While the distance range for organic particle formation is
not necessarily the same as for the influence of VOC on ozone
formation, it may be appropriate to include sources within 100
kilometers of the nonattainment area for both purposes, as the
commenter recommended. However, any state wishing to include such
sources outside the nonattainment area must justify the distance range
that is appropriate for the area.
The EPA is not prepared at this time to establish generally
applicable guidance with respect to how RFP plans should address
ammonia in cases where that precursor is found to be significant.
States that expect to regulate ammonia emissions should consult their
regional office regarding appropriate approaches for their particular areas.
Finally, EPA agrees with the commenter that EPA should revisit the
range of issues regarding geographic distances of impacts as more
information and understanding become available.
6. Pollutants To Be Addressed in the RFP Plan
a. Background
A number of commenters appeared to be confused by the discussion in
the notice of proposed rulemaking regarding the pollutants to be
included in the RFP assessment. The EPA proposed that the attainment
demonstration would provide the key parameters of the RFP
demonstration, and that the list of pollutants to be addressed in the
RFP demonstration would match the list of pollutants regulated as part
of the attainment demonstration. However, the notice of proposed
rulemaking also suggested that the presumptions regarding whether
different pollutants are to be regulated under NSR and RACM (including
RACT) would also apply to RFP. This led some commenters to recommend
different treatment of specific pollutants.
In fact, the presumptions of applicability that EPA is promulgating
for RACM are not germane to RFP. The pollutant coverage of RFP
assessments is determined on an area-specific basis according to each
area's attainment demonstration, and EPA need not establish
presumptions as to what pollutants are included in the RFP assessment.
For example, if a state includes no NOX emission reductions
in its attainment plan, then the RFP plan would not include NOX,
irrespective of whether the (uncontrolled) NOX emissions
contribute significantly to the areas PM2.5 concentrations.
The contrast between establishment of presumptions for RACM and
having no such presumptions for RFP (or for attainment demonstrations)
reflects differences in regulatory context. For RACM, at issue is
whether the impact of the pollutant is sufficient to warrant full
implementation of the RACM requirements. In contrast, for RFP (as for
attainment plans), EPA is establishing
[[Page 20639]]
an overall progress requirement that may be met by applying various
control levels to various pollutants, so long as overall emission
reductions are adequate. Indeed, if the state chooses not to control a
particular pollutant in its attainment plan, then the presumption is
that that pollutant would not be reduced in the RFP plan either.
Furthermore, states have the flexibility to meet the overall progress
with any adequate combination of control of relevant pollutants,
regardless of the significance or insignificance of these pollutants'
impacts. For these reasons, EPA is making no presumptions as to what
pollutants will be included in RFP plans.
b. Final Policy
As proposed, the pollutants to be addressed in the RFP plan are
those pollutants that are subject to control measures in the attainment
plan.
c. Comments and Responses
Comment: A commenter states that ``VOC should be considered a
presumptive PM2.5 precursor.'' Another commenter recommends
presuming that VOC and ammonia are included in the RFP plan.
Response: The EPA's approach to RFP does not rely on presumptions
as to whether a pollutant does or does not warrant regulation as a
precursor. Instead, pollutants are to be included or excluded according
to whether the attainment demonstration includes emission controls for
the pollutant that yield quantitative air quality benefits. Thus,
irrespective of the presumptions applicable to RACM, the RFP plan would
not include VOC unless the attainment plan reflects air quality
improvements from VOC emission controls. The challenges of addressing
VOC as part of an RFP plan were discussed earlier in this section.
Similarly, ammonia would not be included in the RFP plan if the
attainment plan does not regulate ammonia emissions.
7. Equivalent Air Quality Improvement
a. Background
The EPA proposed that states could use alternative combinations of
various types of emission control programs to meet RFP requirements if
the alternative would be expected provide air quality improvements that
are approximately equivalent to those of the benchmark emission
reductions. Some control programs for some pollutants can be
implemented more quickly than other control programs. EPA believes that
it is unnecessary to require that all pollutants be reduced at the same
rate or by the same fraction of the ultimate attainment plan
reductions. The EPA believes instead that the states should have
flexibility to ``mix and match'' control strategies, so long as they
provide a demonstration that the adopted approach can be expected to
yield approximately the same air quality progress as an approach in
which the state achieves an identical fraction of the attainment
strategy for all pollutants by the RFP milestone date.
The notice of proposed rulemaking presented examples of the
assessment of RFP, illustrating EPA's recommended approach for
establishing a benchmark set of emission reductions and illustrating
EPA's recommended procedures for whether modified approaches that
control some pollutants earlier than other pollutants may be considered
equivalent. While not repeated here, the examples remain appropriate
for describing the approach included in the final rule. (See 70 FR
66012-66013).
Most commenters supported EPA's proposal to allow alternative
combinations of control that can be shown by simple means to be
equivalent. A set of commenters objected to this approach, given the
uncertainties involved in the equivalency assessment. Nevertheless, for
this aspect of RFP policy, EPA's final policy reflects the policy that
it proposed.
b. Final Policy
The EPA is adopting an approach that establishes a benchmark level
of controls but allows states the flexibility to adopt any combination
of controls of the various pollutants that can be shown to provide
equivalent benefits using procedures that EPA is recommending (or at
the State's option, air quality modeling). The first step is to
determine the ratio of the number of years from the baseline year to
the RFP review year (e.g., the 7 years from 2002 to 2009) divided by
the number of years from the baseline year to the year in which
attainment level emissions are achieved (e.g. the 10 years from 2002 to
2012, for an area with a 2013 attainment deadline). The benchmark level
of controls is then determined by multiplying this ratio times the
level of control being achieved for each pollutant. For example, for an
area with an attainment deadline extended to 2013, the benchmark level
of controls would reflect \7/10\ of the emission reductions of each
pollutant that is controlled in the attainment plan.
The equivalency process involves consideration of the air quality
benefits for the emission reductions in the alternative plan for each
regulated pollutant. In effect, the air quality benefits for each
pollutant are used as weighting factors, such that pollutants for which
controls yield larger benefits are weighted more heavily in determining
the adequacy of the resulting plan. For each pollutant, the first step
is to find the ratio of the emission reductions achieved by the RFP
milestone date (e.g. the emission reductions achieved between 2002 and
2009) divided by the emission reductions achieved by the attainment
date. The second step is to multiply this ratio times the air quality
improvement attributable to full implementation in the attainment year
of the attainment strategy relevant to that pollutant. The third step
is to add these pollutant-specific results to obtain a total estimated
air quality benefit of the alternative plan.
The air quality benefits of the benchmark reductions are easier to
determine. The first step, inherent to defining the benchmark
reductions, is to determine the ratio of the number of years to the RFP
review divided by the number of years to attainment level emissions (in
the example above, \7/10\). The second step is simply to multiply this
ratio times the quantity of air quality improvement achieved by the
attainment plan. (Conceptually, the calculations are the same as are
done for the alternative plan, but the mathematics are simpler because
one is applying the same assumed fraction of the attainment plan
emission reductions (e.g. \7/10\) for all pollutants, so that there is
no need to subdivide by pollutant.) For each milestone date, any
alternative that provides estimated air quality benefits by the RFP
milestone date that at a minimum are generally equivalent to the
estimated benefits of the benchmark level of emission reductions will
be considered to satisfy RFP requirements.
c. Comments and Responses
Comment: A set of commenters argues that the equivalency process is
too uncertain, and recommends instead that states be required to
achieve at least a fixed percentage reduction for all pollutants. The
commenters cite the uncertainties acknowledged by EPA, including
potential nonlinearity (i.e. that a given percentage of an emission
reduction may yield a different percentage of the related air quality
benefit). The commenters contrast EPA's willingness to accommodate
these uncertainties, for purposes of giving states flexibility for
alternate RFP plan designs, with EPA's unwillingness to accommodate the
uncertainties inherent
[[Page 20640]]
in regulating ammonia emissions. The commenters state that ``Rather
than propose a standardized process for coherently determining
`equivalency,' EPA embraces the possibility that States will invent
multiple and disparate methodologies.'' The commenters argue that the
need for certainty in achieving emission reductions trumps the benefits
of state flexibility, not the other way around. The commenters state
that if ``EPA decides nonetheless to accept equivalency demonstrations,
it should at least * * * require States to conduct dispersion
modeling'' to confirm equivalency. The commenters further find unlawful
the fact that EPA would allow ``rough equivalency'' rather than full
equivalency to the benchmark approach. The commenters would prefer that
EPA required a fixed percentage reduction of the emissions of direct
PM2.5 emissions and of each precursor.
Response: The EPA believes that its proposed approach satisfies the
intent of the RFP requirement, which is to make ongoing, steady
progress toward attainment rather than backloading control strategies.
A requirement to obtain at least a given percentage of each of the
pollutants that contribute to PM2.5 concentrations would
impose an inflexibility that EPA concludes is unnecessary where not
required by the statute. The EPA proposed to require that areas achieve
emission reductions that are generally linear, and a plan that provides
for rough equivalency to the benchmark approach would indeed provide
generally linear reductions. In response to commenters' requests for a
standardized process for assessing equivalency, EPA believes the
process outlined in the final rule is responsive to this request. It is
not clear whether the fixed reduction percentage that certain
commenters recommended would be an area-specific percentage (such as
EPA uses to define the benchmark approach) or a universally applicable
percentage (such as 3 percent per year). If the former, then EPA would
repeat the response above regarding flexibility being consistent with
the Act's requirements; if the latter, then responses in III.6.4
regarding a fixed reduction percentage apply. The EPA believes that the
procedures it is establishing to assess equivalency are adequate for
assessing RFP and that dispersion modeling need not be required for
this purpose.
8. Other RFP Issues
a. Multi-State Nonattainment Areas
As stated in the proposed rulemaking, EPA seeks to ensure that
nonattainment areas that include more than one State meet RFP
requirements as a whole. Some commenters expressed concern about how
one state's submittal should address emissions in other states,
including how the state might address questions about the
enforceability of another state's requirements.
The issues here resemble the issues for attainment demonstrations.
In that context as well, EPA seeks plans that reflect active
consultation by the affected states and provide a combination of
reductions that are enforceable by the respective states that
collectively provide for attainment. The active involvement of regional
planning organizations helps assure a collective design of a plan with
specific requirements to be adopted by specific states. Likewise for
RFP, EPA would expect states with multi-state nonattainment areas to
consult with other involved states, to formulate a list of the measures
that they will adopt and the measures that the other state(s) will
adopt, and then to adopt their list of measures under the assumption
that the other state(s) will adopt their listed measures. That is, each
state would be responsible for adopting and thereby providing for
enforcement of its list of measures, and then that state and ultimately
EPA (at such time as the plan is approved) would be responsible for
assuring compliance with the SIP requirements.
In accordance with this view of RFP, as is the case for attainment
plans, EPA expects states sharing a multi-state nonattainment area to
submit a common assessment of whether RFP will occur. As a default, if
the assessment only includes emissions within the nonattainment area,
then each state would submit an assessment based on emissions from the
full nonattainment area including portions of the area in other states.
If the assessment includes precursor emissions from additional area
outside the nonattainment area, then the states should have a common
rationale for the area included, and all affected states would use the
same inventory of the same multi-state area thus defined in assessing
whether RFP will occur. The EPA would judge such submittals based on
(1) whether the overall projected emission reductions will achieve RFP
and (2) whether the submitting state has adopted the necessary
enforceable measures to assure that the reductions projected within its
boundaries will in fact occur.
As a point of clarification, even if a state justifies
consideration of emissions outside the nonattainment area in its RFP
assessment, EPA intends that these assessments not use emissions from
outside the state or states represented in the nonattainment area. For
single state nonattainment areas, only emissions within that state
would be considered. This will help assure accountability for the
emission reductions included in the plan.
b. Tribal Areas
The EPA received no comments on its proposed policy regarding RFP
for tribal areas, and EPA is finalizing the proposed policy. Under its
Tribal Authority Rule (40 CFR 49.4), EPA found that it was not
appropriate to apply SIP schedule requirements to tribes. For similar
reasons, EPA is not requiring tribes to submit RFP plans. Generally
this exemption will have limited if any impact on the achievement of
RFP by an area. Nevertheless, consistent with its general role in
implementing programs for tribes where ``necessary and appropriate,''
EPA will work with the affected tribes and states to ensure that
emissions on tribal lands are addressed appropriately. The EPA intends
to ensure that areas that include both state and tribal lands will
satisfy RFP on a collective basis, similar to the policy applicable to
multi-state nonattainment areas.
9. Mid-Course Review
a. Background
The EPA proposed requiring mid-course reviews on a case-by-case
basis. The proposal described a mid-course review as a combination of
reviews aimed at assessing whether a nonattainment area is or is not
making sufficient progress toward attainment of the PM2.5
standards. The proposal described the mid-course review as involving
``three basic steps: (1) Demonstrate whether the appropriate emission
limits and emission reduction programs that were approved as part of
the original attainment demonstration and SIP submittal were adopted
and implemented; (2) analyze available air quality, meteorology,
emissions and modeling data and document relevant findings; and (3)
document conclusions regarding whether progress toward attainment is
being made using a weight of evidence determination.'' (Cf. 70 FR 66010)
The EPA views mid-course review requirements as part of a set of
requirements for implementing the Clean Air Act requirements for
reasonable further progress. For areas that demonstrate attainment by
April 5, 2010, EPA believes that this attainment demonstration also
demonstrates that reasonable further progress is being achieved. For
areas that demonstrate
[[Page 20641]]
attainment after April 5, 2010, EPA is requiring states to submit an
RFP plan, due on April 5, 2008, showing that emissions in 2009 and, in
some cases, in 2012, will be sufficiently reduced to provide generally
linear progress toward levels that are expected to yield attainment. At
issue here is how then to conduct ongoing tracking of whether the
planned progress toward attainment is in fact occurring. Subparts 2
(for ozone) and 4 (for PM10) include explicit requirements
for ongoing milestone tracking. Since Subpart 1 (applicable for
PM2.5) allows EPA flexibility in determining how ongoing
progress is to be tracked, EPA may adopt other approaches for achieving
the necessary assurances that ongoing progress toward attainment is
occurring.
Milestone reviews can be confounded by changes in inventory methods
(a concern expressed by a commenter particularly with respect to
condensable emissions) and involve lengthy delays while inventories are
compiled before planning can begin. Other approaches involving only air
quality data reviews also do not provide for timely planning, insofar
as such approaches involve waiting for three years of air quality data
after implementation of controls before planning can begin. The EPA
believes that a mid-course review provides the most productive
approach, in lieu of establishing milestone tracking or other
requirements, to assure that reasonable further progress in reducing
emissions is being achieved. For this reason EPA proposed a requirement
for mid-course reviews.
The EPA proposed a process for establishing and implementing mid-
course review. After the state submits an attainment plan (due in April
2008), EPA would evaluate whether a mid-course review is warranted
after considering various factors including factors identified in the
proposal. The EPA did not propose to conduct further rulemaking on
establishing this requirement, but EPA proposed that ``[w]here EPA
finds that a MCR would be required, the approval of the [attainment]
demonstration would be contingent on a commitment from the State to
conduct the MCR.'' The mid-course review would then be due April 2010.
The EPA's proposal also stated that ``EPA would determine [based on
review of the mid-course review] whether additional emissions
reductions are necessary,'' so that states would need to complete the
mid-course review ``three or more years before the applicable
attainment date to ensure that any additional controls that may be
needed can be adopted [in timely fashion].'' Finally, EPA stated ``[i]f
a mid-course review will be required for certain PM2.5
nonattainment areas, separate PM2.5 mid-course review
guidance will be written to address the specific requirements of
PM2.5 nonattainment areas.''
The EPA received numerous comments objecting to EPA's proposed
approach. Several commenters noted the inconsistency between requiring
a mid-course review in April 2010 versus requiring a mid-course review
due 3 or more years before an attainment date of 2012 or earlier.
Multiple commenters objected to EPA requiring a mid-course review only
2 years after the initial attainment plan is due. A commenter requested
``nationally applicable guidance on when an MCR would be required and
what it would need to include.'' No commenters supported EPA's timeline
for mid-course reviews.
Based on the comments that EPA received, EPA has reevaluated the
process for mid-course reviews. Upon reevaluation, EPA shares many of
the concerns expressed by commenters about the proposal. The proposal
indeed presents conflicting dates for submittal. The EPA agrees that a
deadline just 2 years after the initial SIP submittal is too soon for
states to conduct meaningful analyses of whether areas are making
progress towards attainment. This problem would be exacerbated by the
proposed process, in particular the fact that states would not know to
begin work on a mid-course review until after they had submitted their
initial SIP and after EPA had sufficiently reviewed the submittal to
determine the need for a mid-course review. An early mid-course review
also would defeat one of the purposes of the mid-course review, which
is to take advantage of advances in the science and understanding of
the nature of condensables and other components of PM2.5, to
adjust plans to be better targeted at solving problems. For these
reasons, EPA is significantly revising its approach to mid-course
reviews as recommended by the commenters. The EPA is establishing a
rule which provides more certainty to the states as to applicability
and content of mid-course review requirements, thereby avoiding the
need for future EPA rulemakings on the subject. The EPA's rule clearly
does not require states with early attainment dates to conduct a mid-
course review and would clearly mandate a mid-course review only for
areas with later attainment dates. The EPA's final rule clarifies the
content of mid-course reviews and provides for states to make decisions
on whether further controls are needed rather than having EPA make this
determination. The mid-course review shall include an updated modeled
attainment demonstration as well as a review of the implementation of
measures in the April 2008 SIP and a review of recent air quality data.
The EPA believes that all of these elements are necessary and should be
sufficient for the state to identify whether additional measures are
needed to achieve attainment by the attainment date in the approved
plan. The EPA believes that states, not EPA, should make the initial
determination as to whether additional measures are needed, and EPA has
designed its mid-course review requirements to provide for the states
to make this determination.
The EPA is promulgating a fixed date of April 2011 as a date for
submittal of mid-course reviews for areas with attainment dates in 2014
or 2015. This fixed date will facilitate joint planning for multiple
areas to apply common assumptions regarding regional transport. This
date also gives states adequate notice for preparing these reviews and
adequate time after the April 2008 submittal to incorporate new
information and understanding of PM2.5 nonattainment
problems to adjust attainment strategies as appropriate.
The EPA is not requiring areas demonstrating attainment by 2013 or
before to conduct a mid-course review. Such areas plan to have
attainment level emissions by 2012, and EPA believes that an April 2011
mid-course review would not provide a timely reassessment of such
areas' attainment plans. Instead, EPA is clarifying that mid-course
reviews are only required for areas that demonstrate a need for an
attainment date extension at least to April 2014.
b. Final Rule
For each area with an approved attainment date in 2014 or 2015, EPA
is requiring the state to submit a mid-course review by April 2011. The
mid-course review shall include an updated attainment demonstration as
well as a review of the implementation status of measures included in
the April 2008 submittal and a review of recent air quality data. The
state shall determine whether additional measures are needed for timely
attainment, just as the state is responsible for determining whether
additional measures are needed in the April 2008 attainment
demonstration, subject to formal EPA SIP review. The EPA is not
requiring RFP milestone reviews, and EPA is requiring mid-course
reviews for areas with sufficiently extended attainment dates in lieu
of any other form of tracking reasonable progress.
[[Page 20642]]
c. Comments and Responses
Comment: A number of commenters objected to EPA's proposed
timeframe that would have areas submit a mid-course review only 2 years
after the initial SIP is due. They recommended, instead, that areas
with attainment dates 2 years or more beyond the first 5-year period
submit mid-course reviews 3 years after the SIPs are due (April 2011)
and every 3 years thereafter, if necessary. Their reason for this
suggestion is that the timing of mid-course review requirements needs
to be clearer and should allow adequate time between plans and mid-
course reviews if they are to serve as meaningful reviews.
Several commenters also noted an inconsistency in the timing of
mid-course review requirements under EPA's proposal. The EPA proposed
that mid-course review submittals would be due 5 years after the
initial designation, which for all the original designations means 5
years after April 2005, i.e. April 2010. However, EPA also proposed
that mid-course reviews would be due 3 years before the attainment
date, which for areas with an April 2012 attainment date means April
2009. The commenters considered April 2009 for a mid-course review
submittal to be too soon after the initial SIP submittal in April 2008,
arguing that EPA would not have had time to review the 2008 SIP
submittal, and the states would not have time to prepare a mid-course
review by 2009. Some of these commenters expressed a view that EPA
should not require mid-course reviews earlier than 3 years after the
SIP submittal date.
Response: The EPA agrees with these comments. The EPA is remedying
the inconsistency in submittal dates by establishing the single
submittal due date of April 2011 that was recommended by the
commenters. As requested by commenters, EPA is also clarifying the
applicability of the mid-course review requirement. The requirement
shall apply to areas with attainment dates of 2014 or 2015; mid-course
reviews shall not be required for areas that are expected to attain the
standards by 2013.
Comment: A commenter supports mid-course reviews as a means of
assuring that areas with longer-term compliance dates are on track to
attain the NAAQS as expeditiously as practicable.
Response: The EPA agrees that mid-course reviews can be a critical
step in assuring expeditious attainment for areas with extended
attainment dates. Indeed, EPA is relying on mid-course reviews rather than
milestone reviews or other forms of RFP tracking to serve this purpose.
Comment: A commenter recommended eliminating mid-course review
requirements for any area with less than seven years between SIP
submittal and attainment. The commenter urged that EPA carefully
reconsider its overall timelines for PM2.5 while considering
the feasibility and practical usefulness of the steps required of
States and emission sources.
Response: The EPA agrees that the proposed timeline potentially
required mid-course reviews in areas where such reviews would not be
warranted, and the timeline did not provide the clarity as to the
applicability of the requirement that states need to fulfill their
planning responsibilities. In response, EPA is not requiring mid-course
reviews for areas demonstrating attainment prior to 2014. For those
areas that cannot demonstrate that attainment will occur prior to 2014,
EPA has streamlined the mid-course review process so that the state
bears responsibility for making the initial determination as to whether
additional measures are needed to achieve timely attainment, rather
than requiring additional steps of EPA rulemaking and initial findings
by EPA as to the level of controls needed in the state's SIP. With the
revised timetable, states can be assured of a meaningful mid-course
review effort that focuses on the areas that particularly warrant such
a review and for which time is available for a productive assessment of
the need for additional measures.
Comment: One commenter stated that the proposal that allows the
Agency to determine whether or not a State needs to submit a mid-course
review with their attainment demonstration on a case-by-case basis
lacks sufficient information. Since these attainment demonstrations
must meet rigorous criteria, and require substantial work by the
States, the commenter is concerned that the proposal neglects to
outline the criteria EPA will use to make the case-by-case mid-course
review determinations. The commenter asks that EPA provide the States
with nationally applicable guidance on when an MCR would be required
and what it would need to include.
Response: The EPA agrees with this comment. In particular, EPA
agrees that establishing clear criteria for applicability and content
of a mid-course review requirement will provide states the opportunity
to plan for these reviews and conduct appropriate reviews in a timely
fashion. Therefore, this final rule is establishing specific criteria
for the applicability of the mid-course review requirement, namely that
a mid-course review shall be conducted for any area that cannot
demonstrate attainment before 2014. This final rule is also identifying
the necessary elements of this mid-course review, i.e. a review of the
implementation of measures in the 2008 SIP, and review of recent air
quality data, and an updated modeled attainment demonstration.
H. Contingency Measures
a. Background
Under subpart 1 of the CAA, all PM2.5 nonattainment
areas must include in their SIPs contingency measures consistent with
section 172(c)(9). Contingency measures are additional control measures
to be implemented in the event that an area fails to meet RFP or fails
to attain the standards by its attainment date. These contingency
measures must be fully adopted rules or control measures that are ready
to be implemented quickly upon failure to meet RFP or failure of the
area to meet the standard by its attainment date. The preamble to the
proposal stated that the SIP should contain trigger mechanisms for the
contingency measures, specify a schedule for implementation, and
indicate that the measures will be implemented without significant
further action by the State or by EPA. The contingency measures should
consist of other control measures for the area that are not included in
the control strategy for the SIP.
The April 16, 1992 General Preamble provided the following
guidance: ``States must show that their contingency measures can be
implemented without further action on their part and with no additional
rulemaking actions such as public hearings or legislative review. In
general, EPA will expect all actions needed to affect full
implementation of the measures to occur within 60 days after EPA
notifies the State of its failure.'' (57 FR at 13512.) This could
include Federal measures and local measures already scheduled for
implementation, as explained below.
The EPA has approved numerous SIPs under this interpretation--i.e.,
that use as contingency measures one or more Federal or local measures
that are in place and provide reductions that are in excess of the
reductions required by the attainment demonstration or RFP plan. (62 FR
15844, April 3, 1997; 62 FR 66279, December 18, 1997; 66 FR 30811, June
8, 2001; 66 FR 586 and 66 FR 634, January 3, 2001.) The key is that the
statute requires that contingency measures provide for additional
emission reductions that are not relied
[[Page 20643]]
on for RFP or attainment and that are not included in the
demonstration. The purpose is to provide a cushion while the plan is
being revised to meet the missed milestone. In other words, contingency
measures are intended to achieve reductions over and beyond those
relied on in the attainment and RFP demonstrations. Nothing in the
statute precludes a State from implementing such measures before they
are triggered. In fact, a recent court ruling upheld contingency
measures that were previously required and implemented where they were
in excess of the attainment demonstration and RFP SIP. See LEAN v. EPA,
382 F.3d 575, 5th Circuit., 2004.
One basis EPA recommends for determining the level of reductions
associated with contingency measures is the amount of actual
PM2.5 emissions reductions required by the control strategy
for the SIP to attain the standards. The contingency measures are to be
implemented in the event that the area does not meet RFP, or attain the
standards by the attainment date, and should represent a portion of the
actual emissions reductions necessary to bring about attainment in
area. Therefore, the emissions reductions anticipated by the
contingency measures should be equal to approximately 1 year's worth of
emissions reductions necessary to achieve RFP for the area.
As stated previously, EPA believes that contingency measures should
consist of other available control measures beyond those required to
attain the standards, and may go beyond those measures considered to be
RACM for the area. It is important, however, that States make decisions
concerning contingency measures in conjunction with their determination
of RACM for the area, and that all available measures needed in order
to demonstrate attainment of the standards must be considered first;
all remaining measures should then be considered as candidates for
contingency measures. It is important not to allow contingency measures
to counteract the development of an adequate control strategy
demonstration.
The preamble to the proposal stated that contingency measures must
be implemented without ``significant further action'' after EPA
determines that the area has either failed to meet RFP, or has failed
to attain the standard by its attainment date. The purpose of the
contingency measure provision is to ensure that corrective measures are
put in place automatically at the time that EPA makes its determination
that an area has either failed to meet RFP or failed to meet the
standard by its attainment date. The EPA is required to determine
within 90 days after receiving a State's RFP demonstration, and within
6 months after the attainment date for an area, whether these
requirements have been met. The consequences for states which fail to
attain or to meet RFP are described in section 179 of the CAA.
2. Final Rule
The final rule includes regulatory text for contingency measures
and maintains the overall policy approach as described in the preamble
to the proposal. The key requirements associated with contingency
measures are:
--Contingency measures must be fully adopted rules or control measures
that are ready to be implemented quickly upon failure to meet RFP or
failure of the area to meet the standard by its attainment date.
--The SIP should contain trigger mechanisms for the contingency
measures, specify a schedule for implementation, and indicate that the
measures will be implemented without further action by the State or by EPA.
--The contingency measures should consist of other control measures for
the area that are not included in the control strategy for the SIP.
--The measures should provide for emission reductions equivalent to
about 1 year of reductions needed for RFP, based on the overall level
of reductions needed to demonstrate attainment divided by the number of
years from the 2002 base year to the attainment year. Contingency
measures are those measures that would not be included in the
attainment strategy for various reasons; for example, they may not be
as economically feasible as other measures that are considered to be
RACM, or it may not be possible to implement the measures soon enough
to advance the attainment date (e.g. federal mobile source measures
based on the incremental turnover of the motor vehicle fleet each year).
3. Comments and Responses
Comment: Several comments were received concerning the requirement
for contingency measures under section 172(c)(9). The proposal
indicated that contingency measures adopted as part of the State plan
are to be equal to approximately 1 year's worth of emissions reductions
necessary to achieve RFP, as determined by the attainment demonstration
for the area. One commenter indicates that this amount of reductions
for contingency measures may be excessive in some cases. The commenter
stated that States should be allowed to demonstrate appropriate amount
of reductions for contingency measures in each area based on the degree
of the PM2.5 nonattainment area problem and the progression
of emission reductions planned for the area as a part of the SIP.
Response: The EPA agrees that the CAA does not include the specific
level of emission reductions that must be adopted to meet the
contingency measures requirement under section 172(c)(9). One possible
interpretation of the CAA would assume that contingency measures should
be in place in the event that all of the State's measures fail to
produce their expected emission reductions. Under this scenario, the
State theoretically would be required to adopt sufficient contingency
measures to make up for the entire short fall. In other words, the
State would have to adopt ``double'' the measures required to satisfy
the applicable emissions reduction requirements.
The EPA believes that this scenario would be highly unlikely and
that this interpretation would be an unreasonable requirement. The
adoption of double the measures needed for attainment would be
difficult for States. Therefore, the EPA believes that it is reasonable
that contingency measures should, at a minimum, ensure that an
appropriate level of emissions reduction progress continues to be made
if attainment or RFP is not achieved, or if an area fails to attain the
standard by its statutory attainment date and additional planning is
needed by the State. The EPA believes that the contingency measures
adopted by the State for the affected area should represent a portion
of the actual emissions reductions necessary to bring about attainment
in the area. Therefore, EPA believes that it is reasonable to require
states to adopt contingency measures equal to approximately 1 year's
worth of emissions reductions necessary to achieve RFP for the area.
Comment: One commenter claimed that EPA incorrectly quoted the CAA
as requiring SIPs to provide for implementation of contingency measures
upon an attainment or RFP failure, without ``significant'' further
action by the State or EPA. The commenter stated that section 172(c)(9)
does not contain the word ``significant.'' The CAA requires that
contingency measures take effect ``without further action'' by the
State or EPA.
Response: The EPA agrees with the commenter that the general
requirements for attainment plans specified under section 172(c)(9)
State that each plan must contain additional measures that will take
effect without
[[Page 20644]]
`further action' by the State or EPA if an area either fails to make
RFP or fails to attain the standard by the applicable attainment date.
Section 51.1012 of the final rule describes the contingency measures
requirement and does not include the word ``significant.'' However, as
a matter of practicality states need to take minimal steps to make
contingency measures effective and alert the affected public that the
measures are in force. Thus, EPA has indicated based on conclusions
first made in the 1992 General Preamble that states should complete all
of these administrative steps within 60 days and that all regulatory
steps be completed before SIP submission.
Comment: The commenter further states that EPA is wrong in
asserting that contingency measures can include Federal measures and
local measures already scheduled for implementation, or previously
implemented measures that provide `excess' reductions. The CAA requires
contingency measures to consist of controls `to be undertaken if ' the
area fails to meet attainment or RFP. The commenter states that this
language clearly states that such measures are to be new measures that
will be undertaken upon the triggering event specifically to address
RFP or failure to attain, not measures already in place, or measures
required for other reasons.
Further, the commenter claims that EPA can not rationally refer to
any reductions prior to an attainment or RFP failure as `excess' when
total reductions in the area in fact prove insufficient to meet
attainment RFP. The commenter states that EPA cites a 5th Circuit case
as support, but the commenter respectfully submits that the case was
incorrectly decided on this issue for the aforementioned reasons.
Response: In response to comments claiming that EPA is wrong in
asserting that contingency measures can include Federal measures and
local measures already scheduled for implementation, or previously
implemented measures that provide `excess' reductions, as stated
previously, the EPA has approved numerous SIPs under this
interpretation. The statute requires that contingency measures provide
for additional emission reductions that are not relied on for RFP or
attainment and that are included in the attainment demonstration for
the area. These measures are intended to provide a ``cushion'' in terms
of emissions reductions for the area while the State is revising the
SIP for the area due to the failure to show RFP or attain. In other
words, contingency measures are intended to achieve reductions over and
beyond those relied on in the attainment and RFP demonstrations.
Nothing in the statute precludes a State from implementing such
measures before they are triggered.
As noted above, EPA's General Preamble interpreted the control
measure requirements of sections 172(c)(9) and 182(c)(9) to allow
nonattainment areas to implement their contingency measures early. 57
FR 13498, 13511 (April 16, 1992). The EPA has applied this
interpretation in rulemakings. See, for example, 67 FR 6,590, 6,591-92
(September 26, 2002). See also rulemakings cited in the Background
section, above. As set forth above, the Fifth Circuit has upheld EPA's
interpretation. Louisiana Environmental Action Network v. EPA, 382 F.3d
575 (Fifth Cir. 2004). (``LEAN'') Commenters have not provided a basis
for concluding that the Fifth Circuit in the LEAN case wrongly
interpreted the CAA.
Commenters contend that the language in the CAA regarding
contingency measure controls ``to be undertaken'' requires measures not
already in place or required for other reasons. The Fifth Circuit
disagreed, finding that the terms in section 172(c)(9)--``to be
undertaken'' and ``to take effect''--were ambiguous, and finding
persuasive EPA's interpretation that this language allows measures
already in place or otherwise required. The Court held:
``Here, the EPA's allowance of early reductions to be used as
contingency measures comports with a primary purpose of the CAA--the
aim of ensuring that nonattainment areas reach NAAQS compliance in
an efficient manner--and necessary requirements of the CAA.'' 382
F.3d at 583.
The Court further found that ``By utilizing contingency measures early,
the contingency measures ensured that `an appropriate level of
emissions reduction progress' would be implemented while the State
`adopt[ed] newly required measures resulting from the bump-up to a
higher classification.'' [citing the General Preamble]. Id.
In addition, the Court agreed with EPA that ``early reductions are
necessary in order to create an incentive for nonattainment areas to
implement `all reasonably available control measures as expeditiously
as practicable' '' in accordance with section 172(c)(1) of the CAA.
Thus the Court concluded that it would be ``illogical to penalize
nonattainment areas that are taking extra steps, such as implementing
contingency measures prior to a deadline, to comport with the CAA's
mandate that such states achieve NAAQS compliance as `expeditiously as
practicable.' '' Id. at 583-584.
The Fifth Circuit also endorsed the concept of ``excess''
reductions, noting that the reductions credits at issue in that case,
``although already implemented, are in effect set aside, `to be applied
in the event that attainment is [not] achieved' and such reduction
credits `are not available for any other use.' [citations omitted]. The
setting aside of a continuing, surplus emissions reduction fits neatly
within the CAA's requirement that a necessary element of a contingency
measure is that it must `take effect without further action by the
State or [EPA]'.'' The Court concluded that ``the early activation of
continuing contingency measures is consistent with the purpose and
requirements of the CAA statute.'' Id. at 584.
Thus, EPA's approval of early implemented contingency measures is
consistent with the CAA, as well as with EPA guidance. For example, EPA
has consistently taken the position that ozone nonattainment areas
classified moderate and above must include sufficient contingency
measures so that ``upon implementation of such measures, additional
emissions reductions of up to 3 percent of the emissions in the
adjusted base year inventory (or such lesser percentage that will cure
the identified failure) would be achieved in the year following the
year in which the failure has been identified.'' 57 FR at 13511 (EPA's
General Preamble). Thus the contingency measures are supposed to ensure
that progress towards attainment will occur while the relevant State
adopts whatever additional controls may be necessary to correct a
shortfall in emissions reductions. Id. The EPA has historically allowed
early reductions--that is, reductions achieved before the contingency
measure is ``triggered''--to be used as contingency measures. See also
August 13, 1993 Memorandum from G.T. Helms: Early Implementation of
Contingency Measures for Ozone and Carbon Monoxide (CO) Nonattainment
Areas).
The commenter's argument that emission reductions cannot be valid
contingency measures if they are otherwise required is also misplaced.
A State must have the legal authority to require whatever reductions it
may require as a contingency measure. As EPA has previously stated,
``all contingency measures must be fully adopted rules or measures.''
62 FR 15844, 15846 (April 3, 1997). The fact that the State or Federal
government has already exercised that authority is irrelevant because,
as noted above, contingency measures must ``take effect
[[Page 20645]]
without further action by the State or [EPA].'' Section 172(c)(9).
Thus, by definition, the State necessarily will have already exercised
its legal authority to require reductions as a contingency measure
before the measure is triggered. It does not matter whether or not a
specific contingency measure is already required by law, as long as the
emissions reductions that will result from that contingency measure
have not been accounted for in the attainment and reasonable further
progress demonstrations. If the reductions from the contingency measure
are not available for any other use, then they are surplus that is set
aside in the event reasonable further progress or attainment is not
achieved.
A key element of a valid contingency measure reduction is that the
State may not use the reduction in its attainment or reasonable further
progress demonstrations if it is already using the reduction as a
contingency measure. Those demonstrations must account for the actual
emissions reductions that will make reasonable further progress
towards, and achieve attainment of the NAAQS in the absence of
contingency measures.
I. Transportation Conformity
Transportation conformity is required under CAA section 176(c) (42
U.S.C. 7506(c)) to ensure that Federally supported highway and transit
project activities are consistent with (``conform to'') the purpose of
the SIP. Conformity currently applies to areas that are designated
nonattainment, and those redesignated to attainment after 1990
(``maintenance areas'' with plans developed under CAA section 175A) for
the following transportation-related criteria pollutants: ozone,
particulate matter (PM2.5 and PM10), carbon
monoxide (CO), and nitrogen dioxide (NO2). Conformity to the
purpose of the SIP means that transportation activities will not cause
new air quality violations, worsen existing violations, or delay timely
attainment of the relevant NAAQS (or ``standards'').
The final PM2.5 implementation rule does not contain any
revisions to the transportation conformity regulation. The EPA
addressed the transportation conformity requirements that apply in
PM2.5 nonattainment and maintenance areas in three separate
rulemakings as described below.
First, on July 1, 2004, EPA published a final rule (69 FR 40004)
that addressed the majority of requirements that apply in
PM2.5 areas including:
? Regional conformity tests to be used in conformity
determinations both before and after SIPs are submitted and motor
vehicle emissions budgets are found adequate or are approved;
? Consideration of direct PM2.5 emissions in
regional emissions analyses;
? Consideration of re-entrained road dust in
PM2.5 regional emissions analyses;
? Consideration of transportation construction-related
fugitive dust in PM2.5 regional emissions analyses; and
? Compliance with PM2.5 SIP control measures.
Then on May 6, 2005, EPA promulgated a final rule (70 FR 24280)
that specified the transportation-related PM2.5 precursors
and when they apply in transportation conformity determinations in
PM2.5 nonattainment and maintenance areas.
Finally, on March 10, 2006, EPA promulgated a final rule (71 FR
12468) that establishes the criteria for determining which
transportation projects must be analyzed for local particle emissions
impacts in PM2.5 and PM10 nonattainment and
maintenance areas. If required, an analysis of local particle emissions
impacts is done as part of a transportation project's conformity
determination.
Transportation conformity for the PM2.5 standards began
applying in PM2.5 nonattainment areas on April 5, 2006, one
year after the effective date of EPA's PM2.5 nonattainment
designations (i.e., April 5, 2005). CAA section 176(c)(6) and 40 CFR
93.102(d) provide a one-year grace period before conformity applies in
areas newly designated nonattainment for a new standard.
PM2.5 SIP submissions such as RFP and attainment
demonstrations would identify motor vehicle emissions budgets
(``budgets'') for direct PM2.5 or PM2.5
precursors, as described below. These budgets would be used for
satisfying transportation conformity requirements, once the budgets are
found adequate or the SIP containing the budgets is approved by EPA.
For example, state and local agencies would consider during the
development of the PM2.5 SIP whether reductions of on-road
mobile source S02 emissions are a significant contributor to
an area's PM2.5 air quality problem, and if so, establish a
S02 motor vehicle emissions budget for transportation
conformity purposes.
The EPA has previously addressed its intentions regarding when
budgets must be established in PM2.5 SIPs for transportation
conformity purposes. RFP plans, attainment demonstrations, and
maintenance plans must include a budget for direct PM2.5
emissions, except for certain cases as described below. All
PM2.5 SIP budgets would include directly emitted
PM2.5 motor vehicle emissions from tailpipe, brake wear, and
tire wear. States should also consider whether re-entrained road dust
or highway and transit construction dust are significant contributors
and should be included in the PM2.5 budget. For further
information, see 40 CFR 93.102(b) and 93.122(f) of the transportation
conformity regulation, as well as Sections VIII-X of the July 1, 2004
conformity rule preamble at 69 FR 40031-40036.
Under certain circumstances, directly emitted PM2.5 from
on-road mobile sources may be found an insignificant contributor to the
air quality problem and NAAQS. Section 93.109(k) of the conformity rule
states that ``[s]uch a finding would be based on a number of factors,
including the percentage of motor vehicle emissions in the context of
the total SIP inventory, the current state of air quality as determined
by monitoring data for that NAAQS, the absence of SIP motor vehicle
control measures, and historical trends and future projections of the
growth of motor vehicle emissions.'' The EPA discussed its intentions
for applying the insignificance provision in the July 2004 final rule
(69 FR 40061-40063).
In the May 6, 2005 final rule, EPA provided details regarding when
states must establish SIP budgets for any PM2.5 precursor
(i.e., NOX, VOCs, S02 and ammonia). If through
the SIP process a state concludes that on-road mobile source emissions
of one or more precursors are significant (i.e. need to be addressed in
order to attain the PM2.5 standards as expeditiously as
practicable), then EPA expects that the state will include a budget in
the SIP for each of the relevant precursors. (70 FR 24287) The EPA also
noted in the May 2005 conformity rule that, if inventory and modeling
analyses demonstrating RFP, attainment or maintenance indicate a level
of emissions of a precursor that must be maintained to demonstrate
compliance with the applicable requirement, then that level of
emissions should be clearly identified in the SIP as a budget for
transportation conformity purposes, even if the SIP does not establish
particular controls for the given precursor. If the state fails to
identify such a level of emissions as a budget, EPA will find the
submitted SIP budgets inadequate because the SIP fails to clearly
identify the motor vehicle emissions budget as required by the
conformity rule (40 CFR 93.118(e)(4)(iii)). (70 FR 24287) In
determining whether the on-road mobile source emissions of a
PM2.5 precursor are significant, state and local agencies
would use the criteria for insignificance findings provided in 40 CFR
93.109(k)
[[Page 20646]]
of the transportation conformity regulation. A further discussion of
the criteria to be considered in establishing PM2.5
precursor budgets is contained in the May 2005 final transportation
conformity rule (70 FR 24282-24288). If state and local agencies
conclude that on-road sources of a precursor are not a significant
contributor to the area's PM2.5 air quality problem, as
described above, motor vehicle emissions budgets would not be
established even though emissions may be addressed in the area's RFP
plan, attainment demonstration and/or maintenance plan.
J. General Conformity
a. Background
The General Conformity regulations promulgated in 1993 establish an
implementation process where Federal agencies are responsible for
making their own determination of conformity with State implementation
plans (SIPs), and EPA plays an advisory role. Recognizing that it was
impracticable to evaluate all Federal actions for conformity, EPA
created a number of exemptions in those regulations for actions with
insignificant or not reasonably foreseeable emission increases,
including exemptions for Federal actions with emissions below specified
de minimis levels. When a Federal agency must demonstrate conformity
for an action, the regulations provide several methods for making that
demonstration. With the designations of PM2.5 nonattainment
areas on April 5, 2005, requirements for demonstrating conformity
become effective in those areas on April 5, 2006.
On July 17, 2006 EPA issued a final rule (71 FR 40420) to amend the
General Conformity Regulations to establish de minimis levels for
PM2.5 for the General Conformity program. The final rule
established 100 tons/year of direct PM2.5 emissions and its
precursors as the de minimis level where the General Conformity
regulations would apply in PM2.5 nonattainment areas. In the
process of finalizing the de minimis level for PM2.5 three
comments were received. One commenter was concerned about emissions
from burning by Federal agencies. Another commenter proposed that the
de minimis level for emissions of direct PM2.5 should be set
significantly lower than 100 tons--in the range of 25-50 tons per year
(TPY) in areas that are likely to attain the PM2.5 national
ambient air quality standard within 5 years, and a level of 10-25 TPY
in areas that are likely to take more than 5 years to achieve the
national ambient air quality standard. A third commenter supported the
proposed de minimis level.
The final rule revises the tables in sub-paragraphs (b)(1) and
(b)(2) of the General Conformity Regulations by adding a de minimis
emission level for PM2.5 and its precursors. This action
maintained our past policy of consistency between the conformity de
minimis emission levels and the size of a major stationary source under
the New Source Review program (70 FR 65984). These levels are also
consistent with the levels promulgated for Reasonably Available Control
Technology applicability levels for volatile organic compound and
nitrogen oxide emissions in subpart 1 areas under the 8-hour ozone
implementation strategy (68 FR 32843). Since EPA is not finalizing any
classifications for the PM2.5 nonattainment areas, we did
not establish differing PM2.5 de minimis emission levels for
higher classified nonattainment areas.
b. Comments and Responses
Comment: One commenter requests that EPA communicate to all Federal
agencies the value of the agencies advising the States as soon as
possible of any planned future projects in nonattainment areas that may
be above the General Conformity de minimis values or that will have to
be evaluated to show that they are below de minimis. This is for
projects that are very likely to proceed. The aim is to consider these
future emissions in any growth projections during SIP development since
such growth may not be anticipated well by the available growth model
(E-GAS). States can communicate with existing Federal facilities now
concerning this issue.
Response: The EPA sees the value in Federal agencies working with
States to anticipate growth in emissions and include those anticipated
emissions in the applicable SIP. The EPA is in the process of proposing
regulatory amendments to the General Conformity regulations that
provide a framework for Federal facilities to work with States to
account for facility-wide emissions in SIPs and to include Federal
facility emissions in future SIPs. The EPA anticipates that these rule
amendments should be proposed before the end of summer 2006.
Comment: Some commenters stated that the de minimis level for
PM2.5 for conformity applicability should be less than 100
tons per year. A level of 50 tons per year was suggested for direct
PM2.5 emissions.
Response: Similar comments were received when the PM2.5
de minimis level was proposed on April 5, 2006. The response to those
comments can be found in the preamble to the final rule setting the de
minimis level for PM2.5 at 71 FR 40420.
Comment: Are the precursors for general conformity consistent with
this rulemaking or with the transportation conformity rulemaking?
Response: The precursors for general conformity are generally
consistent both with this rule and the transportation conformity rule.
The only difference between the transportation rule and this rule is
that SO2 is not considered a precursor for transportation
conformity determinations that occur prior to a PM2.5 SIP
unless EPA or the State air agency finds on-road mobile source
emissions significant. For more information, see the May 6, 2005
transportation conformity rule on PM2.5 precursors at 70 FR 24283.
Since general conformity includes analysis of stationary sources
the general conformity rule requires SO2 as a precursor both
before and after a PM2.5 SIP is submitted.
Comment: When will rulemaking containing the de minimis levels for
PM2.5 and for the precursors be issued? There is some
confusion, since the proposed rule says that states should assume 100
tpy for all PM2.5 pollutants, as this would make it
consistent with the levels for NOX and VOC for the subpart 1
areas under 8-hour ozone. However, since New Jersey's classification is
moderate under the 8-hour ozone standard and we are in an Ozone
Transport Region, the de minimis level for VOC is 50 tons per year.
Response: On July 17, 2006 EPA issued a final rule (71 FR 40420) to
amend the General Conformity Regulations to establish de minimis levels
for PM2.5 for the General Conformity program. The final rule
established 100 tons/year of direct PM2.5 emissions and its
precursors as the de minimis level where the General Conformity
regulations would apply in PM2.5 nonattainment areas. Since
EPA is not finalizing any classifications for the PM2.5
nonattainment areas, we did not establish differing PM2.5 de
minimis emission levels for based on a classification scheme.
Comment: If a Statement of Conformity has been issued on a project
and if the project has not been completed to date, are they required to
address PM2.5 prior to completion of the project or will
they be grandfathered in?
Response: If a Federal action has completed a conformity
determination and the action has started (regardless of whether the
project is complete or not) then no new determination is needed. If
[[Page 20647]]
the conformity determination was completed, but the action did not
start in 5 years a new determination is needed under the general
conformity rules.
Comment: What guidance should states use to establish budgets for
large facilities or military bases?
Response: The EPA has not issued any guidance for States and
Federal facilities to establish facility-wide budgets in the applicable
SIP. There is nothing in the General Conformity regulations preventing
this approach which would allow Federal actions that do not increase
total facility emissions over the budget in the SIP from determining
the action conforms on the basis of its compliance with the budget
limit. The EPA sees this practice as a positive step to encourage
States and Federal agencies to work together to account for emissions
in a SIP so they conform with the purposes and goals of the SIP. The
EPA intends to address the approach and provide guidance in planned
revisions to the General Conformity regulations which are expected to
be proposed in 2006.
K. Emission Inventory Requirements
a. Background
Emission inventories are critical for the efforts of State, local,
tribal and federal agencies to attain and maintain the NAAQS that EPA
has established for criteria pollutants including PM2.5.
Pursuant to its authority under section 110 of Title I of the CAA, EPA
has long required States to submit emission inventories containing
information regarding the emissions of criteria pollutants and their
precursors. The EPA codified these requirements in 40 CFR part 51,
subpart Q in 1979 and amended them in 1987.
The 1990 CAAA revised many of the provisions of the CAA related to
attainment of the NAAQS and the protection of visibility in mandatory
Class I Federal areas (certain national parks and wilderness areas).
These revisions established new emission inventory requirements
applicable to certain areas that were designated nonattainment for
certain pollutants. In the case of particulate matter, the emission
inventory provisions are in the general provisions under Section 172(c)(3).
In June 2002, EPA promulgated the Consolidated Emissions Reporting
Rule (CERR) (67 FR 39602; June 10, 2002), 40 CFR part 51 subpart A. The
CERR consolidated the various emissions reporting requirements that
already existed into one place in the CFR, established new reporting
requirements for PM2.5 and ammonia, and established new
requirements for the statewide reporting of area source and mobile
source emissions.
The CERR established two types of required emission inventories:
annual inventories, and 3-year cycle inventories. The annual inventory
requirement is limited to reporting statewide emissions data from the
larger point sources. For the 3-year cycle inventory, States need to
report data from all of their point sources plus all of the area and
mobile sources on a statewide basis. A special case existed for the first
3-year cycle inventory for the year 2002 which was due on June 1, 2004.
The EPA issued guidance suggesting that 2002 be used as the Base
Year for 8-hour ozone, PM2.5 and regional haze planning
efforts (November 18, 2002 EPA memorandum ``2002 Base Year Emission
Inventory SIP Planning: 8-hr Ozone, PM2.5 and Regional Haze
Programs'' http://www.epa.gov/ttn/chief/eidocs/2002baseinven_102502new.pdf).
States should estimate mobile source emissions by using the latest
emissions models and planning assumptions available at the time the SIP
is developed. Information and guidance on the latest emissions models
is available at http://www.epa.gov/otaq/stateresources/transconf/policy.htm#models
and at http://www.epa.gov/otaq/models.htm.
By merging the information on point sources, area sources and mobile
mobile sources into a comprehensive emission inventory, State, local
and tribal agencies may do the following:
? Set a baseline for SIP development.
? Measure their progress in reducing emissions.
? Have a tool to support future trading programs.
? Answer the public's request for information.
The EPA uses the data submitted by the States to develop the
National Emission Inventory (NEI). The NEI is used by EPA to show
national emission trends, as modeling input for analysis of potential
regulations, and other purposes.
Most importantly, States need these inventories to help in the
development of control strategies and demonstrations to attain the
annual and 24-hour PM2.5 NAAQS. In April 1999, EPA published
the ``Emissions Inventory Guidance for Implementation of Ozone and
Particulate Matter National Ambient Air Quality Standards (NAAQS) and
Regional Haze Regulations,'' EPA-454/R-99-006. The EPA updated this
guidance in November 2005.\46\ The current version of this guidance is
available at: http://www.epa.gov/ttn/chief/eidocs/eiguid/index.html.
The EPA developed this guidance document to complement the CERR and to
provide specific guidance to State and local agencies and Tribes on how
to develop emissions inventories for 8-hour ozone, PM2.5,
and regional haze SIPs. While the CERR sets forth requirements for data
elements, EPA guidance complements these requirements and indicates how
the data should be prepared for SIP submissions.
---------------------------------------------------------------------------
\46\ Emissions Inventory Guidance for Implementation of Ozone
and Particulate Matter National Ambient Air Quality Standards
(NAAQS) and Regional Haze Regulations,'' (EPA-454/R-05-001, November 2005.
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The SIP inventory must be approved by EPA as a SIP element and is
subject to public hearing requirements, whereas the CERR is not.
Because of the regulatory significance of the SIP inventory, EPA will
need more documentation on how the SIP inventory was developed by the
State as opposed to the documentation required for the CERR inventory.
In addition, the geographic area encompassed by some aspects of the SIP
submission inventory will be different from the statewide area covered
by the CERR emissions inventory. The CERR inventory was due June 1,
2004, while the SIP inventory due date is later. Because of this time
lapse, the State may choose to revise some of the data from the CERR
when it prepares its SIP inventory to account for improvements in
emissions estimates. If a State's 2005 emission inventory (or a later
one) becomes available in time to use for timely development of a
nonattainment area SIP, then that inventory can be used. We also
encourage the cooperation of the Tribes and the State and local
agencies in preparing their emissions inventories.
b. Final Rule
In the proposed rulemaking, in Sec. 51.1008(a), to meet the
emission inventory requirements of section 172(c)(3), EPA proposed to
require submission of the CERR inventories as well as ``any additional
emission inventory information needed to support an attainment
demonstration and RFP plan ensuring expeditious attainment of the
annual and 24-hour PM2.5 standards.'' Section 51.1008(b) set
forth specifications for baseline emissions inventories for attainment
demonstrations and RFP requirements. Section 51.1008 of the final rule
reflects our proposed rule but is different from the draft regulatory
text. The proposal did not specify a deadline for
[[Page 20648]]
submission of the emission inventory. To ensure clarity, the final rule
contains language addressing the deadline for submission of emissions
inventories for nonattainment areas under section 172(c)(3) and section
172(b), and reflects the statutory requirement of no later than 3 years
after designation of the area. See Sec. 51.1008(a). In addition, Sec.
51.1008(a)(1) of the proposed rule has been changed for purposes of
clarification. The proposal referred to the requirement to submit
statewide emission inventories under the (CERR), contained in 40 CFR
part 51, subpart A. The final regulatory text clarifies this to refer
to the requirements for data elements under 40 CFR part 51, subpart A.
The EPA did not intend that the emissions inventories developed under
the CERR, which are statewide, would be appropriate for and satisfy all
aspects of SIP inventories developed for SIP submissions. Section
51.1008(b) has a minor change to clarify that this subsection refers to
the inventories required for submission under paragraph (a) of section
51.1008, and also clarifies the reference to 40 CFR Part 51 subpart A,
which currently contains the CERR. In addition, section 51.1008(b) as
finalized provides that ``The baseline emission inventory for calendar
year 2002 or other suitable year shall be used for attainment planning
and RFP plans for areas initially designated nonattainment for the
PM2.5 NAAQS in 2004.'' The EPA added this flexibility to be
consistent with EPA's ozone implementation rule, and to enable a State
to use a more recent and improved base year inventory if it is
completed in time to allow for timely development of the attainment
plan. As noted above, we expect that States will consult the guidance
document titled Emission Inventory Guidance for Implementation of Ozone
and Particulate Matter National Ambient Air Quality Standards
(``NAAQS'') and Regional Haze Regulations, November 2005,and submit
inventories that are appropriate for the geographic area at issue and
consistent with regulations and this guidance. We expect the States to
include in their SIP submission documentation explaining how the
emissions data were calculated.
In the proposed rulemaking, EPA asked ``What emission inventory
requirements should apply under the PM2.5 NAAQS.'' Several
specific questions followed this general question to assess whether or
not additional emission inventory requirements or guidance are needed
to implement the proposed standard. It was noted in the proposal that
the basis for EPA's emission inventory program is specified in the
Consolidated Emissions Reporting Rule (CERR) and the related guidance
document titled Emissions Inventory Guidance for Implementation of
Ozone and Particulate Matter National Ambient Air Quality Standards
(NAAQS) and Regional Haze Regulations.
Subsequent to the proposed rulemaking, EPA proposed the Air
Emissions Reporting Rule (AERR) at 71 FR 69 (Jan. 3, 2006). The AERR
would update CERR reporting requirements by consolidating and
harmonizing new emissions reporting requirements with pre-existing sets
of reporting requirements under the Clean Air Interstate Rule (CAIR)
and the NOX SIP Call. At this time, EPA is reviewing
comments submitted on the AERR proposal and expects to finalize this
rulemaking during calendar year 2007. The AERR is expected to be a
means by which the Agency will implement additional data reporting
requirements for PM2.5 SIP emission inventories. Since the
AERR rulemaking is in progress, EPA believes it is appropriate to defer
responding to certain comments on the proposed PM2.5
Implementation Rule related to data reporting and emission inventory
requirements that were discussed in the AERR proposal. Those comments
will be addressed in the final AERR rulemaking. Significant comments
that are separable from the AERR rulemaking and relate to data
reporting and emission inventory requirements for the PM2.5
NAAQS are addressed below and in EPA's Responses to Comments document.
With respect to SIP emission inventory requirements under this
rulemaking, EPA recognizes NOX, SO2, VOCs, and
ammonia as potential precursors of PM2.5 because these
pollutants can contribute to the formation of PM2.5 in the
ambient air. To provide a technical foundation for understanding
contributions to PM2.5 nonattainment problems and for
identifying potential future measures to reduce PM2.5
concentrations, EPA is requiring under 40 CFR part 51 subpart A and 40
CFR 51.1008 of this rule that States develop and submit inventories for
direct PM2.5 and all precursors of PM2.5. This
requirement stands apart from the policies in this rule regarding the
required treatment of various precursor emissions in the development of
control strategies for attaining the PM2.5 standards. With
respect to the latter requirements, EPA has not made a finding that all
precursors should be evaluated for potential control measures in each
specific nonattainment area. The policy approach in the rule instead
requires evaluation of control measures for direct PM2.5 and
sulfur dioxide in all areas, and describes general presumptive policies
that NOX sources need to be evaluated for control measures
in all areas unless findings of insignificance are made, but that
control measure evaluations are not required for sources of ammonia and
VOC unless findings of significance are made. The rule also provides a
mechanism by which the State and/or EPA can make an area-specific
demonstration to reverse the general presumption for these three
precursors. (See section II.A.8 for additional discussion on these issues.)
c. Comments and Responses
1. Should EPA Specify an Inventory Approval Process?
Comment: Several commenters indicated that the current process of
approving SIP inventories by EPA regional offices is appropriate and
did not believe that additional approval requirements were necessary.
Some commenters noted that flexibility is needed to address regional
concerns. Several commenters noted that SIP emission inventories may
include requirements or information in addition to data required by the
Consolidated Emissions Reporting Rule (CERR). One commenter observed
that States routinely develop information outside the CERR for purposes
of their SIP development and that additional requirements should not be
defined by EPA. Another commenter recommended that requirements for
nonattainment area emission inventories be incorporated in the CERR or
AERR. A few commenters felt that additional guidance was needed on the
SIP emission inventory approval process.
Response: The SIP emissions inventory is a plan provision that must
be approved by EPA under section 110(k) of the CAA and is subject to
public hearing requirements pursuant to section 110(a)(2). The EPA
believes that it need not further specify a SIP approval process for
emissions inventories beyond that set forth in the statute, regulation
(51.1008), other related sections of this rulemaking and EPA's current
guidance. The EPA agrees with many of the commenters that the approval
process for SIP emission inventories need not be further defined and
that approval should be conducted at the regional level to provide
flexibility to address regional concerns. The EPA also agrees that use
of Quality Assurance Project Plans developed for each state will be
helpful in establishing the proper approval process. The EPA
[[Page 20649]]
addresses the issue of what data elements are needed for SIP approval
in the responses to comments below, including the responses to comments
under Issue 2, below.
As noted by two commenters EPA describes procedures for approval of
SIP inventories in a document titled Emissions Inventory Guidance for
Implementation of Ozone and Particulate Matter National Ambient Air
Quality Standards (NAAQS) and Regional Haze Regulations, November 2005.
Section 2.5, Inventory Approval, references a memorandum titled Public
Hearing Requirements for 1990 Base-Year Emissions Inventories for Ozone
and CO Nonattainment Areas, September 29, 1992. The EPA intends to use
the procedures discussed in the guidance and memorandum to the extent
that they are applicable to approval of PM2.5 emission
inventories submitted as part of the SIP. 40 CFR 51.1008 sets forth the
requirements for emissions inventories under section 172(c)(3), which
will be reviewed in the context of the SIP approval process. See also
40 CFR 51.1007 and 51.1009 regarding attainment demonstrations and RFP
plans. Thus, EPA believes that its existing SIP approval process is
adequately described in statute, regulation and guidance, and that it
provides flexibility to deal with issues that arise in individual
nonattainment areas.
2. Are the Data Elements Specified Within the CERR Sufficient To
Develop Adequate SIPs? For Example, in the Determination of RACT,
Should More Information on Existing Control Devices Be Required?
Comment: Several commenters recommended that any additional
reporting requirements should be addressed through the CERR/AERR and
associated guidance and that no additional reporting requirements
should be specified in the Rule. Another commenter stated that more
detail concerning control equipment would be helpful but was concerned
about the additional burden on industry compared to the benefit to
State and local agencies, and suggested that this would be further
addressed in the context of comments on the AERR. One commenter
believed that the reporting requirements within the CERR are sufficient
to develop a PM2.5 SIP for most areas but noted that
nonattainment areas may require additional inventory information which
will need evaluation on a case-by-case basis. The commenter further
stated that any additional inventory requirements should be identified
during the SIP development process, in cooperation with the EPA
regional office, and should not be part of this rule.
Response: In section 40 CFR 51.1008(a)(1) of the final rule, EPA
incorporates the requirements for data elements required under 40 CFR
part 51, subpart A, which contains the CERR, for inventories submitted
under this section. The EPA notes, however, that the issue of whether
to require additional reporting requirements beyond those required in
the CERR is currently being addressed in the Air Emissions Reporting
Rule (AERR) 71 FR 69 (January 3, 2006). At this time EPA believes that
the requirements for data elements under the CERR, in conjunction with
the other provisions of 40 CFR 51.1008, as well as 40 CFR 51.1007 and
51.1009, are generally adequate to meet the needs for PM2.5
nonattainment emission inventory SIP development. The AERR as proposed
includes additional provisions which may be helpful for
PM2.5 SIP emission inventory development. The EPA will
address this aspect of the AERR, including comments received in this
rulemaking on the issues raised and the additional elements proposed in
the AERR, in the final AERR rulemaking. This final rule indicates that
States shall include data elements for PM2.5 inventories as
required under 40 CFR part 51, subpart A. In addition, 40 CFR
51.1008(a)(2) requires that States submit ``any additional emission
inventory information needed to support an attainment demonstration and
RFP plan ensuring expeditious attainment of the annual and 24-hour
PM2.5 standards.'' See also 40 CFR 51.1007 and 51.1009. Thus
States should be aware that data elements in addition to those required
under the CERR may be needed to support attainment demonstrations and
RFP inventories. Additional data elements needed for other SIP emission
inventory purposes should be handled on a case-by-case basis. Because
of the nature of SIP development, which varies depending on the nature
and needs of individual areas, it may not be possible to require a
level of detail in regulations that will enable a ``one-stop-shop''
information request as suggested by one of the commenters.
As recommended by one commenter, guidance on reporting requirements
is contained in Emissions Inventory Guidance for Implementation of
Ozone and Particulate Matter National Ambient Air Quality Standards
(NAAQS) and Regional Haze Regulations (EPA-454/R-05-001, November
2005). For example, Section 3.2.1 for Pollutant and Pollutant
Precursors to be Inventoried presents guidance to states on
PM2.5 pollutants and their components that should be
reported for PM2.5 SIP development. See also section 5,
Emission Inventory Development, and other related sections of the guidance.
With respect to the comment on additional detail on control
requirements, see also EPA's Response to Comment Document.
3. Is the Current Approach for Reporting Specific Pollutants
Sufficient, or Should EPA Require More Specific Emission Component
Reporting Such as Groups of Compounds or Reporting of Elemental Carbon
and Organic Carbon?
Comment: Currently the CERR requires the reporting of
SO2, VOC, NOX, CO, Pb, PM10,
PM2.5, and NH3. VOC and PM are speciated by the
emissions processing models based on speciation profiles for specific
source categories. Most commenters supported retaining the existing
reporting requirements under the CERR. Others encouraged expansion of
the requirements to include reporting of specific organic compounds and
organic fractions although some thought this should be a requirement
while others thought it should be optional. One commenter thought that
EPA should work with industry trade groups to develop and improve the
speciation profiles of the most important source categories rather than
asking the state and local agencies to characterize VOC and PM species.
Several commenters thought that EPA should encourage the reporting of
PM components (filterable, condensable and total) for development of
control strategies and attainment demonstrations. Another commenter
noted that including condensable emissions raises ``uncertainty''
issues and urged EPA to devote resources to developing better test
methods. One commenter believed that in addition to reporting
PM2.5 and its components, states should report all precursors
to PM2.5 (SO2, NOX, ammonia and VOC).
Response: The EPA agrees with the commenters who argued that the
need for additional speciation should be determined based on specific
SIP needs. 40 CFR part 51, subpart A which contains the CERR, does not
require reporting of specific compounds or compound groups nor does it
require reporting of organic and elemental carbon fractions. As
discussed in the response to comment above, EPA believes that the
requirements for data elements contained in 40 CFR part 51 subpart A,
in conjunction with the provisions of 40 CFR 51.1008, are generally
adequate to meet the needs for PM2.5 nonattainment emissions
[[Page 20650]]
inventory SIP development. Section 51.1008(a)(1) applies the data
element requirements contained in 40 CFR part 51 subpart A. Section
51.1008(a)(2) requires States to submit ``any additional emission
inventory information needed to support an attainment demonstration and
RFP plan ensuring expeditious attainment of the annual and 24-hour
PM2.5 standards.'' Thus data elements in addition to those
required under the CERR may be needed to support attainment
demonstrations and RFP inventories under 40 CFR 51.1008(a)(2).
Additional data elements needed for other SIP emission inventory
purposes should be handled on a case-by-case basis. Where States need
to develop speciated emissions for PM2.5 SIP emission
inventories, EPA provides guidance in the document titled Emissions
Inventory Guidance for Implementation of Ozone and Particulate Matter
National Ambient Air Quality Standards (NAAQS) and Regional Haze Ozone
Regulations, November 2005. Section 3.2.1, Pollutants and Pollutant
Precursors to be Inventoried identifies pollutants and their components
to be reported for PM2.5 SIPs. Section 3.3.5, Speciation
Procedures, discusses the preferred approach for speciating
PM2.5 emission inventories for use in ambient air quality
simulations. The approach discussed in the guidance is application of
emission models which use speciation profiles to estimate the mass of
specific compounds and compound groups for VOC and elemental and
organic carbon fractions for PM. The EPA encourages further research
and development of technical tools to better characterize emissions
inventories for specific VOC compounds and to determine the extent of
specific VOC compounds and organic PM mass. The EPA also encourages
States to continue efforts to refine their ammonia inventories. See
sections II.A.3 and II.A.4 of the Preamble.
As discussed in the guidance document, EPA encourages reporting of
organic and elemental fractions of PM2.5 by state agencies
(see Section 3.2.1, Pollutants and Pollutant Precursors to be
Inventoried). While elemental or black carbon (EC/BC) and organic
carbon (OC) will be identified in default speciation profiles, more
locally-specific data should be collected where available as an input
to model preprocessing. Where such data are available, they should be
provided to EPA to help in improving EPA's speciation profiles. Certain
organic gases have been identified as precursors to secondary organic
aerosols (SOA). Toluene, xylene and ethyl benzene are known to be
important SOA precursors. Additional organic gases may be identified by
ongoing research. While these gases will be identified in default
speciation profiles, more locally-specific data should be collected,
where available, as an input to model preprocessing. State, local and
Tribal agencies can contact EPA's EIAG for more information.
EPA agrees with the comment that it should take the lead in
updating VOC and PM profiles for most important source categories. The
Agency is close to completing a multi-year effort to update the
SPECIATE database. SPECIATE is EPA's repository of Total Organic
Compound (TOC) and PM speciated profiles for a wide variety of sources.
The profiles in this system are provided for air quality dispersion
modeling and as a library for source-receptor and source apportionment
type models. This recent initiative to update SPECIATE was needed
because speciated emissions profiles continue to be developed and the
data in the existing EPA database (SPECIATE 3.2) was becoming outdated.
This work was coordinated with interested parties including
industry through an Agency sponsored workgroup. It has depended largely
on the collection and review of existing profile data to accomplish, as
the commenter suggests, delivering the best results for the least
amount of resources spent. Previously, these data were not widely
available to emission inventory developers and lacked the quality
assurance review and evaluation needed to develop profiles used by
emissions models to generate speciated emissions. As suggested by the
commenter, the workgroup was used to help prioritize source categories
for investigation to ensure that updates to existing profiles and
development of new profiles focused on areas of greatest need.
SPECIATE v4.0 contains more than 2500 source profiles and is
currently undergoing peer review. The EPA expects the final work
product to be available for use by emission inventory preparers during
early calendar year 2007 and it will be distributed through EPA's CHIEF
Web site.
The EPA agrees with a commenter who noted that in order to meet the
requirements under section 172(c) of the CAA for ``a comprehensive,
accurate, current inventory * * *,'' condensable emissions of
PM2.5 and PM2.5 precursors are important to
support development of local control strategies and attainment
demonstrations. The EPA believes that the final rule provides for the
submission of PM2.5 nonattainment area inventories meeting
the requirements of section 172(c)(3).
Section 51.1008(a)(1) requires that States submit emission
inventories for PM2.5 that satisfy the data elements
reporting requirements under 40 CFR part 51 subpart A, which contains
the CERR. The CERR requires reporting of ``Primary PM2.5''
which is defined as the sum of the filterable and condensable portions
of PM2.5. Therefore, SIP base year inventories will include
the condensable fraction of PM which was of concern to several
commenters. The CERR also requires reporting of SOx, NOX,
ammonia and VOC which are potential precursors to PM2.5. EPA
notes that the AERR as proposed would require reporting of the same
precursors and would also require reporting of Primary
PM2.5. However, the proposed AERR requires the reporting of
the filterable and condensable fractions of PM2.5 (optional
under the CERR) in addition to the primary PM2.5 total mass.
The EPA will address this requirement in its final rulemaking on the AERR.
As noted above, in addition to the data element requirements under
section 51.1008(a)(1), under section 51.1008(a)(2) States must submit
``any additional emission inventory information needed to support'' an
attainment demonstration and RFP plan. Thus States should be aware that
data elements in addition to those required under the CERR may be
needed to support attainment demonstrations and RFP inventories under
40 CFR Part 51.1008(a)(2). Additional data elements needed for other
SIP emission inventory purposes should be handled on a case-by-case basis.
The EPA is aware of the issues raised by one commenter regarding
measurement uncertainty for condensable PM. This issue is addressed in
detail under Section II.L of the preamble (``Condensable particulate
matter test methods and related data issues,''). We believe that for
purposes of emissions inventories and attainment demonstrations, States
should continue to describe the impacts of baseline emissions and
develop future air quality strategies using information available on
primary PM2.5 emissions, including condensable
PM2.5. However, with respect to developing enforceable
emissions limits for condensable PM2.5 emissions, the final
rule reflects EPA's adoption of a transition period during which we
will allow time for development of emissions limits for condensable
PM2.5. See 40 CFR 51.1002(c).
For additional comments and responses related to speciation issues,
[[Page 20651]]
see the Response to Comments Document.
4. Should EPA Require That States Develop Their Own Estimates for Area
and Mobile Source Emissions?
Comment: The CERR allows states to adopt EPA developed emission
estimates from area and mobile sources in lieu of making those
estimates themselves if they accept these estimates for their emission
inventory. One commenter thought that EPA should require States to
develop their own estimates for area and mobile sources based on the
specified 2002 base year. Three commenters thought that the existing
process (under the CERR) was adequate. One of the commenters expressed
concerns about the reporting burden for States if they were required to
compile their own mobile and area source inventories. Another commenter
did not believe that States should be required to submit data on area
and mobile sources but noted that many States would continue to run the
MOBILE model for onroad mobile sources and calculate area source data
for SIP emission inventories. Two of the commenters thought that the
existing process provided flexibility needed by States to focus on
source categories of most concern and address problematic areas with
special inventory needs. One commenter recommended that EPA continue
developing models for area and mobile sources.
Response: The EPA strongly encourages states to submit their own
estimates for area (nonpoint) and mobile sources unless they can
establish that it is impracticable to do so, given time and resources.
We will continue, in appropriate circumstances, to allow a State to use
EPA-developed emission estimates for mobile and nonpoint sources in
lieu of making those estimates itself if the State accepts the
estimates for its emission inventory. While this has been the case with
respect to reporting under the CERR for the 3-year cycle inventories,
for development of emission inventories to support PM2.5
SIPs, the ability to rely on EPA-developed emission estimates for
development of emission inventories to support PM2.5 SIPS is
more complex and problematic. For mobile sources, the practical use of
these EPA-developed mobile source inventories in a SIP may be very
limited. While EPA has developed inventories for 2002, states will
still have to develop attainment year inventories, including
projections of future activity and the effects of control measures. For
mobile sources, future year inventories are not developed by simply
growing a base year inventory, but instead are developed by running an
emissions model with appropriate inputs for the future year. In order
to develop an attainment demonstration that accurately accounts for the
change in emissions from the base year to the attainment year,
inventories for both of those years will need to be developed using
consistent methods and modeling assumptions. For mobile sources
especially, it may be very difficult for states to replicate the
methods used by EPA for the base year when creating the attainment year
inventory.
In addition, states cannot use the EPA developed inventories for
the base year if newer models or planning assumptions are available at
the time they begin working on the SIP. For example, if new or better
information about the composition of the local fleet of highway
vehicles in the base year becomes available to the state after the EPA
developed inventories were created, that information should be used by
the state to create a new base year inventory.
Given the need for emissions modeling for mobile sources in the
projection year, the need for consistency in tools and methods between
the base year and attainment year, and the need to use latest available
models and planning assumptions, EPA believes that most if not all
states will choose to develop their own base year inventories for
mobile sources.
With respect to nonpoint (area) source emissions, States must make
every effort, consistent with available timing and resources to ensure
that their area source emission inventories are as accurate as
possible. While EPA prepares a national area source emission inventory
that covers all counties, it is designed for national analyses. EPA
does not have access to the more detailed information available to
States that is used to develop an area source inventory. Therefore,
states should develop as much of their area source inventory as
possible using local and State information, and in particular should
develop the inventory for the most significant area source categories
which are critical to ensuring overall accuracy. Where time and
resources preclude a State from developing the estimates for less-
critical area source categories, the State may rely on EPA-developed
area source emissions information for those categories.
The EPA points out that although guidance has recommended that 2002
be used as the base year for emissions inventories for states initially
designated nonattainment in 2004-5, states remain free to use an
alternate base year, as appropriate. Section 51.1008(b) provides in
relevant part that ``The baseline emission inventory for calendar year
2002 or other suitable year shall be used for attainment planning and
RFP plans for areas initially designated nonattainment for the
PM2.5 NAAQS in 2004.''
EPA agrees with the comment that it should continue to develop
models and other emission estimation tools. As an example, EPA's Office
of Transportation and Air Quality (OTAQ) is developing a modeling
system termed the Motor Vehicle Emission Simulator (MOVES). This new
system will estimate emissions for on-road and nonroad sources, cover a
broad range of pollutants, and allow multiple scale analysis, from
fine-scale analysis to national inventory estimation. When fully
implemented MOVES will serve as the replacement for MOBILE6.2 and
NONROAD. In addition, as the NEI is reengineered, OAQPS will examine
the need for updating emissions estimation guidance materials and
developing tools which will assist State agencies in estimating
emissions from area source categories. See also EPA's ``Emissions
Inventory Guidance for Implementation of Ozone and Particulate Matter
National Ambient Air Quality Standards (NAAQS) and Regional Haze
Regulations,'' November 2005.
5. Other Inventory Issues
The EPA's responses to additional comments concerning emission
inventory issues can be found in EPA's Response to Comments Document.
L. Condensable Particulate Matter Test Methods and Related Data Issues
a. Background
As noted in the preamble to the November 1, 2005 proposed rule,
certain commercial or industrial activities involving high temperature
processes (fuel combustion, metal processing, cooking operations, etc.)
emit gaseous pollutants into the ambient air which rapidly condense
into particle form. The constituents of these condensed particles
include, but are not limited to, organic material, sulfuric acid, and
metals. Because condensable emissions exist almost entirely in the 2.5
micrometer range and smaller, these emissions are inherently more
significant for PM2.5 than for prior particulate matter
standards addressing larger particles. Therefore, we believe that it is
important that the air quality management of particulate matter promote
a comprehensive approach to condensable particulate matter.
[[Page 20652]]
We proposed to require a comprehensive inclusion of condensable PM
for all aspects of SIP development for PM2.5. Under the
proposal, EPA would require condensable PM to be considered in the
emissions inventories and analyses used in attainment demonstrations.
Also under the proposal, any stationary source emissions limits
developed to implement RACT or RACM would reflect control and
measurement of condensable PM.
We received numerous comments on whether these requirements were
unreasonable in light of the current state of knowledge of and
uncertainties around the measurement of direct PM2.5. Most
commenters supported the overall view that condensable PM should be
addressed in order to provide a complete air quality management program
for PM2.5. On the other hand, many commenters raised
concerns about the availability and implementation of test methods and
related issues about the uncertainties in existing data for condensable
PM2.5. As a result of the concerns, these commenters
believed EPA would be premature in requiring a comprehensive evaluation
of condensable PM2.5, especially as it related to developing
any new emissions limits for stationary sources. In recognition of
these concerns, the final rule reflects EPA's adoption of a transition
period during which we will assess possible revisions to available test
methods and we will allow time for States to update emissions
inventories as needed to address direct PM2.5 emissions. In
this section of the preamble, we outline the elements of the final rule
addressing inventories reflecting control of direct PM2.5.
We also discuss the specific comments raised regarding methods for
measuring direct PM2.5, both filterable and condensable PM,
in implementing the rule. The particular comment areas include defining
test methods, quantifying direct PM2.5 for inventories, and
a transition period for developing effective regulations. Below are
also our responses to those comments.
b. Final Rule
For the final rule, EPA addresses two broad issues related to
inclusion of condensable PM. The first issue is whether emissions
inventories and attainment demonstrations should include the
condensable portion of direct PM2.5 emissions. The second
issue is whether direct PM2.5 emissions limitations
established by States for purposes of RACT and RACM must include limits
on condensable PM emissions or limits on total direct PM2.5
that includes the condensable PM fraction.
For purposes of developing emissions inventories and attainment
demonstrations, the final rule reflects a requirement to account for
significant contributors of direct PM2.5 emissions, both
filterable and condensable PM2.5. We recognize that some
States have established inventories consistent with requirements of the
consolidated emissions reporting rule (CERR) to report direct
PM2.5 emissions, including condensable PM, in each inventory
revision. While uncertainties remain with significant issues to address
related to our current knowledge base on condensable PM emissions, we
believe that for purposes of emissions inventories and attainment
demonstrations, States should continue to describe the impacts of
baseline emissions develop future air quality strategies using information
available on direct PM2.5 emissions including condensable PM.
With respect to developing enforceable emissions limits for
condensable PM emissions, we note that some States have established
emissions limits or otherwise require PM emissions testing that
includes measurement of condensable PM. We recognize that in some
States there remain questions about the viability of available test
methods, the availability of representative direct PM2.5
emissions data, the uncertainty of the methods used to establish
inventories, and the short time frame within which States must develop
SIPs. In response we have decided to provide a transition period for
developing emissions limits and regulations for condensable PM2.5.
During this transition period, we will provide technical support to States
as requested in establishing effective PM2.5 emissions limits
and corresponding emissions testing requirements.
As described further below, we will devote resources early during
this transition period to assessing and improving the available test
methods for condensable PM. During this transition period, we will also
solicit the involvement of stakeholders with an interest in conducting
emissions testing to collect updated direct PM2.5 emissions
data. The purpose of these stakeholder projects will be to collect new
direct filterable and condensable PM emissions data using methodologies
that provide data more representative of source direct PM2.5
emissions. The EPA, States, and others will use these data to improve
emissions factors and to help define or revise source emissions limits
in permits and State implementation plans.
The time required for our stakeholders and EPA to complete the test
method assessment will limit the degree to which State and local
agencies can address effectively the necessary direct PM2.5
regulations in inventories and in the 2008 SIP submittals. In
recognition of this, we will not require that the emissions limits
included in the 2008 submittals account for the condensable fraction of
direct PM2.5 or to establish limits for total direct
PM2.5, including condensable PM.
We will expect States to continue developing more complete
inventories with regard to direct PM2.5 emissions,
particularly for condensable PM, during this transition period. We
expect no such allowance period for method assessment or data
collection to be necessary for implementing regulations addressing
precursor PM2.5 emissions.
The period of transition for establishing emissions limits for
condensable direct PM2.5 will end January 1, 2011. We expect
States to address the control of direct PM2.5 emissions,
including condensable PM, with any new actions taken after January 1,
2011. For example, States must address condensable PM emissions in any
direct PM2.5 emissions limits resulting from midcourse
reviews. Additionally, EPA expects that any direct PM2.5
regulations or limits developed under any new NAAQS for particulate
matter would also address condensable PM emissions.
Notwithstanding the issues and uncertainties related to condensable
PM, EPA encourages States to identify measures for reducing condensable
PM emissions, particularly where those emissions are deemed significant
contributors to the control strategy needed for expeditious attainment.
We wish to clarify that in order to take credit in the SIP for
reduction of any such condensable PM emissions, there must be
enforceable limitations that ensure that reduction in condensable PM
emissions. These enforceable limits could take the form of a limitation
on the condensable PM emissions or total direct PM2.5
emissions (or a commitment to develop such limitations after the end of
the transition period described above). Alternatively, these
enforceable limitations could provide for enforceable conditions that
ensure that the effect on condensable PM emissions is assured (for
example, enforceable limitations on operating temperature, or limits on
FGD scrubber operations which have the effect of reducing condensable
PM emissions).
[[Page 20653]]
c. Comments and Responses
We received many comments on quantification of direct
PM2.5 emissions particularly about the need to conduct
further validations for the available test methods, the availability of
direct filterable or condensable PM2.5 data or lack thereof
for representative baselines, and the procedures for applying baseline
data for developing effective regulations.
1. Method 202
Comment: A majority of commenters characterized the performance of
Method 202 as lacking in reliability. Some commenters characterized the
formation of artifacts in Method 202 as significant and the primary
reason for their recommendation to defer the inclusion of condensable
particulate matter in the baseline assessments and regulatory
development for the initial SIPs. The commenters stated that the
principal artifact formed when using Method 202 was the result of SO2
dissolving in the impinger water and converting to sulfuric acid.
Response: We agree that SO2 in particular, and perhaps
other gaseous compounds, can react with the collecting liquids used in
the method to form materials (artifacts) that would not otherwise be
solid or liquid or would not condense upon exiting the stack. We
believe that when Method 202 is applied appropriately (i.e., with the
N2 purge as prescribed), the SO2 artifact
formation is reduced by as much as or more than 90 percent; however, we
agree that further verification and refinement would be appropriate to
verify the potential for artifact formation.
In response, we are undertaking laboratory studies in collaboration
with several stakeholders to characterize the artifact formation and
other uncertainties associated with conducting Method 202, and to
identify procedures to be used in applying methods to minimize
uncertainties. We are involving stakeholders representing industry and
State and local agencies in the project design and results review.
Stakeholders who have expressed interest in participating in these
studies include the Electric Power Research Institute, companies
associated with the National Environmental Development Association's
Clean Air Project (NEDA/CAP), the Portland Cement Association, the Lime
Manufacturing Association, the American Foundry Association, the
National Aluminum Association, and several governmental organizations
represented by National Association of Clean Air Agencies. Other
parties may participate in the study as well.
By the end of 2007, we intend to have conducted a comprehensive
laboratory study that examines the relationship between several
critical condensable PM sampling and analysis parameters (e.g.,
SO2 concentration, moisture concentration, sample duration,
and water acidity) and the artifact formation associated with the
measurements. One intended result of the project will be identifying
possible modifications to Method 202 to minimize and quantify the
uncertainties. We will publish the results of the laboratory study
along with an assessment of other input and data from stakeholders on
the EPA website and, to the extent possible, in a widely circulated
peer review journal. Also, to the extent necessary, we intend to
propose revisions to the method to incorporate improvements and to
clarify application.
2. Conditional Test Methods 039 and 040
Comment: Several commenters cited as a deficiency that neither
conditional test method 040 (CTM-040) for measuring filterable
PM2.5 nor the dilution sampling method (CTM-039) has been
thoroughly validated through EPA Method 301. There were also comments
that neither of the CTMs was published in the Federal Register.
Response: We agree with the comments that neither method has been
subjected to adequate public notice and comment rulemaking. Taking that
step will facilitate application of the appropriate methods for
implementing the SIPs. On the other hand, there are a number of levels
of validation already achieved for one or more of these methods that
will determine what, if any, additional validation work will be
necessary. For example, while we could seek resources to evaluate
dilution sampling technology, including CTM-039, and to request public
involvement in the project planning, conduct, and review with the
possibility of a Federal Register proposal, our preference would be to
incorporate by reference an approved voluntary consensus test method
(e.g., ASTM standard).
We believe that a dilution sampling method for measuring direct
PM2.5 eliminates essentially all artifact formation and
provides the most accurate emissions quantification. To the extent that
we need to and can secure resources and stakeholder interest, we plan
to perform additional validation testing of CTM-039 or other dilution
sampling technologies to characterize the precision of this approach.
In conjunction with our validation efforts, we intend to continue
participation in the ASTM D22 committee to develop and publish a
dilution sampling method and encourage other volunteers on that
committee to approve the consensus based dilution sampling method. We
believe that this work is nearly complete. As outlined above, we are
already undertaking laboratory studies to assess the method and to
identify possible modifications to reduce formation of these artifacts.
Preliminary laboratory evaluations conducted by EPA and by Environment
Canada\47\ indicate that additional artifact reductions of 60 to 90
percent may be achieved with other minor modifications to Method 202.
These preliminary findings indicate that Method 202 is essentially a
viable method that these proposed laboratory studies will serve to
enhance. Within 18 months we intend to propose, if necessary,
modifications to Method 202 or similar methodologies suitable for
measuring condensable PM2.5.
---------------------------------------------------------------------------
\47\ ``Optimized Method 202 Sampling Train to Minimize the
Biases Associated with Method 202 Measurement of Condensable
Particulate Matter Emissions,'' John Richards, Tom Holder, and David
Goshaw, Air Control Techniques, P.C.; Air & Waste Management
Association, Hazardous Waste Combustion Specialty Conference AWM,
November 2-3, 2005, St. Louis, MO.
---------------------------------------------------------------------------
As for CTM-040, we believe that further validation of this method
is unwarranted since the technology and procedures are based upon the
same as evaluated for promulgated Method 201A. Method 201A has
undergone public review and comment (55 FR 14246, April 17, 1990).
Also, as noted earlier, we have already begun laboratory and data
evaluation work the possible result of which would be a revised Method
202 to be proposed in the Federal Register to include improvements
indicated by the evaluation. At that same time, we may propose CTM-040
to be used in combination with Method 202 for measuring direct
PM2.5 with additional guidance on appropriate approaches to
testing for direct PM2.5 emissions from various types of
control measures (e.g., electrostatic precipitator and flue gas
desulphurization combinations).
3. Role of Condensable PM Emissions in Defining RACT
Comment: Commenters indicated that States must reassess and revise
emissions limits if the States adopt methods for measuring direct
PM2.5 including condensable PM where not required
previously. Commenters noted that most existing PM emissions limits are
not reflective of data collected with
[[Page 20654]]
methods that measure condensable or filterable PM2.5 and,
therefore, not enforceable using a new or different test method.
Response: We agree that coordinating the test method with the
pollutant defined by the emissions limit is critical to an effective
regulation. In the case of direct PM2.5 regulations, the
methods for measuring filterable and condensable PM provide data that
are significantly different than do methods often used in implementing
many current regulations (i.e., filterable plus condensable
PM2.5 versus filterable PM only). The existing PM emissions
regulations implementing many current SIPs have focused almost
exclusively on filterable PM at stack conditions or other elevated
temperatures (e.g., 250 [deg]F) with little or no measurement of
condensable PM, let alone filterable PM2.5. These
deficiencies exist in spite of the Agency's policies and guidance
presented in documents such as the 1987 PM10 SIP Development
Guideline \48\ and the General Preamble for the Implementation of Title
1 of the Clean Air Act Amendments of 1990 \49\ issued in 1992. These
documents set forth Agency policy stating that direct PM10
and direct PM2.5 emissions include both filterable and
condensable particulate matter. The policies are reinforced by a 2005
directive from the CAA Advisory Committee.\50\
---------------------------------------------------------------------------
\48\ U.S. Environmental Protection Agency. PM-10 SIP Development
Guideline. Office of Air Quality Planning and Standards, Research
Triangle Park, NC. EPA Publication No. EPA-450/2-86-001. June 1987.
\49\ The General Preamble is available online at
http://www.epa.gov/ttn/oarpg/t1pfpr.html.
\50\ Clean Air Act Advisory Committee, Recommendations to the
Clean Air Act Advisory Committee--Phase I and Next Steps, Air
Quality Management Work Group, Environmental Protection Agency,
http://www.epa.gov/air/caaac/pdfs/report1-17-05.pdf, January 2005.
---------------------------------------------------------------------------
More to the point, the use of test methods that quantify only
filterable PM would limit the capability of any assessment of control
measures available for developing cost effective strategies to achieve
attainment of the PM2.5 NAAQS. Examples include an
attainment demonstration that includes control methodologies for PM
precursors which are likely to result in a significant decrease in the
emissions of direct PM2.5 (for example, alkaline scrubbers
to reduce SO2 emissions) and incorporate these direct
PM2.5 emissions reductions in their attainment demonstration
or allow for the use of these reductions as credits for other programs.
Some States may decide to measure and control condensable PM
emissions prior to the end of the transition period. To the extent that
a State has the supporting technical information and test methods, the
State may also assess the capabilities of current control technologies,
possible modifications to such technologies, or new technologies as
appropriate relative to control of condensable PM2.5
emissions in developing effective control strategies and regulations.
As an example, a specific approach for controlling condensable PM could
be a change in control device operating temperature to achieve
necessary emissions reductions. We also note that it is important that
implementation of any new or revised rules and test methods should be
prospective and clearly differentiated from existing regulations to
avoid confusion over status of compliance relative to existing PM
emissions limits.
4. Sufficiency of Current Baselines Relative to Direct PM2.5
for Regulatory Development
Comment: Many commenters indicated that the currently available
baselines for direct PM2.5 emissions are not sufficient for
States to develop effective emissions control regulations. One
commenter claimed that States will need additional information
regarding how to arrive at enforceable PM2.5 emissions
limitations through application of correlations to existing
PM10 emissions limitations.
Response: We agree that State inventories accounting for direct
PM2.5 emissions are important to the NAAQS implementation
decision-making process. For example, the current national emissions
inventories have characterized the contribution of the condensable PM
emissions to range from 40 to 80 percent of the direct PM2.5
emissions particularly from combustion source categories. We also agree
in many cases, the emissions baselines are not sufficiently
representative of significant direct PM2.5 contributors to
allow States to develop effective and enforceable emissions limitations
for sources that may require control of direct filterable or
condensable PM2.5 emissions in order for States to come into
attainment with the PM2.5 NAAQS.
We note that States are already required under the consolidated
emissions reporting rule (CERR) to report direct PM2.5
emissions, including condensable PM, in each inventory revision. That
means that inventories and associated baselines must address sources
and contributions of direct PM2.5 emissions, both filterable
and condensable PM, from individual sources and groups of sources as
well as for future year projected emissions. These data are important
for the purposes of calculating emissions reductions and demonstrating
that such reductions are attributable to the control measures being
implemented.
In taking the process to the next step, we contend that many
current baselines established using the available direct filterable and
condensable PM2.5 national industry average emissions
factors (e.g., those found in AP-42 and WebFIRE, http://www.epa.gov/
ttn/chief/efpac/index.html) often are of quality insufficient to
establish effective source-specific emissions limits. First, national
industry average emissions factors are subject to significant
uncertainties as they usually represent data from a very limited number
of example facilities in a category and for a very limited number of
operating conditions. Second, the available emissions factors databases
may not include direct PM2.5 emissions data for specific
source types that appear in some State and local inventories.
In short, we believe that States should rely on directly measured
emissions data in developing source category or pollutant-specific
emissions limits for regulations. This approach is preferable to the
use of these national industry average emissions factors such as those
found in AP-42. If there are no directly measured emissions data
available from the subject sources, national average emissions factors
should be used only with appropriate and significant adjustments for
uncertainty. Based on our initial study \51\ of the uncertainties
associated with national average emissions factors when applied to
site-specific or rule-development activities, we would expect
multipliers of 0.1 to 3.3 for an A-rated national average filterable
and condensable direct PM2.5 emissions factors. The level of
a particular multiplier would depend on how representative of the
source category the applicable emissions factor is, the quantity of
data supporting that emissions factor, and the specific application.
Determining what adjustment may apply for a particular application
requires detailed knowledge of the emissions control variability, the
expected range of operational and process variability, and the
statistical uncertainty in the measured emissions data. While more
general adjustments to emissions factors are possible for these
purposes, we believe that the better approach is to improve and update
the emissions factors used in the database for a particular area with
measured
[[Page 20655]]
direct PM2.5 emissions data. For these reasons and to allow
time for data collection and analysis, we have determined the need for
a period of transition for States in developing direct PM2.5
emissions reduction strategies.
---------------------------------------------------------------------------
\51\ Option Paper 4--Providing Guidance Regarding The Use Of
Emissions Factors For Purposes Other Than Emissions Inventories,
September 2005, http://www.epa.gov/ttn/chief/efpac/projects.html.
---------------------------------------------------------------------------
5. Transition Period
Comment: Some commenters suggested that EPA should allow States to
base their initial 2008 SIPs on NOX, SO2, and
filterable PM or PM10 (as a surrogate for filterable
PM2.5) rather than require State and local agencies to
develop direct PM2.5 emissions regulations immediately.
Commenters suggested that EPA provide a transition period for sources
to adopt SIPs that address direct PM2.5 and to apply the
appropriate test methods. The commenters proposed that during this
transition period, a source should be able to continue to use Method 5,
Method 17, or whatever method was used to set the underlying limit
contained in the source's title V operating permit. Commenters believe
that such a transition plan must provide additional time to collect
data related to condensable PM emissions. Commenters believe that this
additional time is necessary because it is unrealistic to develop SIP
revisions addressing condensable emissions by April 2008. Other
commenters suggested that source emissions inventories used for
regulatory decision-making and identifying regulatory control measures
must be based on accurate measurements.
Response: As outlined above, we agree that a transition period
should be allowed to allow time to resolve and adopt appropriate
testing procedures for condensable PM emissions, to collect total
(filterable and condensable) PM2.5 emissions data that are
more representative of the sources in their areas, and develop
effective regulations for control of direct PM2.5, including
condensable PM.
6. Data Collection for Regulatory Development
Comment: Several commenters recommended that EPA should be
responsible for developing data of emissions from common sources of
direct PM2.5.
Response: We disagree with the commenters' recommendation that EPA
should be primarily or solely responsible for developing baseline data
on common sources of direct PM2.5 emissions. Commenters are
suggesting that we should collect data representative of direct
PM2.5 emissions from source categories potentially subject
to regulation of direct PM2.5 emissions. Furthermore, they
suggest that we expand or improve the current compilation of national
industry average emissions factors such as found in AP-42 and WebFIRE
(http://www.epa.gov/ttn/chief/efpac/index.html). Given the limited
extent to which national industry average emissions factors are
suitable for developing State or local regulations that set limits on
direct PM2.5 emissions, we believe that it is inherent that
States instead have primary responsibility for reviewing and applying
measured emissions data collected from their sources in enhancing their
current baselines. In some cases, this will mean that States and other
stakeholders will need to conduct more focused direct PM2.5
emissions data collection and improve relevant emissions factors.
This approach is appropriate for several reasons. First, we believe
that stakeholders other than EPA are better equipped to identify
specific data needs and that they have the means to collect the data.
Second, we believe we are better positioned to provide guidance on test
planning, data collection, and emissions factors calculations with a
less direct role in data collection and evaluation. Third, we believe
that States in need of additional information can also benefit from
experience of other States with similar source types and who are
developing regulations to implement the NAAQS including the control of
condensable PM. See also the discussion in section II.L.2.c.1 above on
the currently active collaborative study to assess direct
PM2.5 emissions measurement technologies and to collect
updated direct PM2.5 emissions data.
7. Developing Effective Regulations for Direct PM2.5,
Including Condensable PM, Emissions
Most current PM regulations focus on the control and measurement of
filterable PM emissions and do not account for condensable PM
emissions. At issue are assessing and accounting for the differences in
methodology and applicable limits when changing to a program designed to
achieve reductions in PM2.5 emissions, including condensable PM.
Comment: A number of respondents commented that EPA needs to
promulgate a PM2.5 test method and adopt regulatory language
that determines the PM2.5 limits based on that promulgated
PM2.5 test method as soon as possible. Other commenters
suggested that EPA and States have no choice but to revise the
underlying standard by adopting new monitoring requirements through a
notice and comment rulemaking. Further, these commenters indicate that
it is essential that EPA require that no change in a test method or in
methods of monitoring for determining compliance until such time as EPA
or the permitting agency have undertaken a notice and comment process
to determine how the emissions limitations must be revised. A number of
commenters cited specific components necessary for effective regulations.
Response: We agree that notice and comment rulemaking is
appropriate for establishing effective regulations. As noted above, we
are already undertaking a study of the available test methods to
determine the need for regulatory revisions. We also agree that new
regulations limiting direct PM2.5 emissions must include
effective emissions limitations to the extent that a State must reduce
sources of direct PM2.5. How a State determines to take such
regulatory action depends on the State's implementation plan. Regarding
the specific components necessary for effective regulations, see
section O below on enforcement and compliance issues.
M. Improving Source Monitoring
a. Background
In the November 1, 2005 proposal, we discussed a number of actions
the EPA would undertake to improve the effectiveness of existing and
new regulations with improved source monitoring provisions.
Specifically, we repeated a plan outlined on January 22, 2004 (69 FR
3202; a Federal Register notice describing requirements for monitoring
in operating permits), that includes a four-part strategy for improving
monitoring of emissions at the source where necessary through
rulemaking. One element of that plan is for EPA to develop guidance on
how States can reduce PM2.5 emissions by improving source
monitoring related to PM2.5 emissions limits. We noted that
we expect to describe in such guidance methods of improving monitoring
frequency or adopting more appropriate monitoring for States to
consider in developing their PM2.5 SIPs and to illustrate
the amount of credit that States could receive in PM2.5 SIPs
for adopting such improved monitoring. We suggested that States with
areas where additional reductions are needed to help the area achieve
compliance with the NAAQS could implement improved monitoring measures
to obtain additional emissions reductions. We put forward that State
agencies could receive SIP credits as a result of enforceable improved
monitoring or
[[Page 20656]]
voluntary emissions monitoring programs meeting EPA voluntary program
policies.
Specific examples of improved monitoring we outlined included: (1)
Conducting the currently required monitoring more frequently (i.e.,
increased monitoring frequency), (2) changing the monitoring technique
to a parameter more closely related to control of direct or precursor
PM2.5 emissions (i.e., a correlated parametric monitoring
technique), (3) changing the technique to more measurement of direct
PM2.5 emissions and PM2.5 precursors, or (4) a
combination of these improvements. These types of monitoring
improvements could be conducted for both controlled and uncontrolled
emissions units. The improved monitoring control measure would require
facilities to pay more attention to the operation of add-on air
pollution control devices, work practices, and other control measure
activities. The additional attention will reduce periods during which
control devices and other control measures do not operate as intended
or required. The result would be increased emissions reductions from
implementing existing and new rules.
We discussed a range of currently applied and new monitoring
technologies. We addressed concerns we have about the limitations of
the widespread use of visual emissions (VE) monitoring techniques, such
as visible emissions checks, to show compliance with PM emissions
limits. We noted particular concerns about VE approaches, even with
frequent application, having the ability to verify compliance when the
margin of compliance is small or the ability to detect relatively
significant changes in emissions control performance. The other concern
we noted about the use of VE tools is the limited frequency at which
they are conducted. We cited studies on the availability of continuous
instrumental methods for monitoring opacity and operational parameters
closely related to PM control levels including the development of
repeatable correlations between parameter levels and PM emissions. We
noted that PM continuous emissions monitoring systems (PM CEMS)
technology provides the opportunity to quantify PM emissions levels
(concentration or emissions rates). These additional data provide the
source owner/operator with a level of information that can be useful
for understanding and operating the process and the control measures in
ways to minimize emissions, improve operating efficiencies, and reduce
enforcement liabilities. Furthermore, we noted that this technology
will provide the State with quantitative information on PM emissions
which will help improve the inventories and to implement effective
control strategies to meet the NAAQS.
We also discussed at some length what we believe constitutes
improved monitoring and the potential for monitoring-related emissions
reductions. We discussed a study of how these emissions reductions
would be achieved by increasing the monitoring frequency or improving
the monitoring of an add-on air pollution control device or other
process activity above the level currently required in existing rules.
The increased frequency or improved technique would allow owners or
operators to achieve greater emissions reductions by identifying and
responding more quickly to periods of ineffective control measure
operation. States could use an improved monitoring control measure in
regulations or through other means to reduce emissions levels and
receive credits towards attainment. Specifically, we cited materials
that indicate that source owners and operators who increase monitoring
frequency could achieve emissions reductions up to 13 percent and those
who improve the monitoring technique could achieve emissions reductions
up to 15 percent. States with nonattainment areas in need of additional
reductions to achieve compliance with the NAAQS could implement an
improved monitoring measure and develop additional emissions reductions
credits. We outlined several specific examples.
In order to inform our improved monitoring guidance development
efforts, we used the 2005 proposal to solicit specific comments on (1)
how potentially inadequate source monitoring in certain SIPs could be
improved; (2) how improved PM2.5 monitoring relates to title
V monitoring; (3) whether instrumental techniques are more appropriate
than visual emissions (VE) techniques for monitoring compliance with PM
emissions limits; and (4) a basis for determining whether improved
monitoring would be effective and under what conditions should be
required. We also requested comment on the feasibility of monitoring of
co-pollutant control measures and requested examples of improved
monitoring for any applications.
b. Final Rule
We maintain that improved monitoring is critical to implementing
the PM2.5 direct and precursor emissions reductions
programs. We also believe that improving monitoring both in terms of
increasing data collection and analysis frequency and in measuring the
pollutant of interest more directly will accomplish several important
and advantageous outcomes. First, improved monitoring will improve
verification of compliance and assurance of the intended emissions
reductions. Second, improved monitoring can provide additional
emissions reductions through quicker detection and correction of
control measure problems. Third, improved monitoring can improve
operating efficiencies that often result in cost savings to the
facility exceeding the cost of the monitoring. We will continue to
evaluate the effects of improved monitoring on emissions reductions and
ways to quantify the benefits associated with improved monitoring.
We intend to move forward with developing and providing additional
technical and informational materials regarding technologies
constituting improved monitoring and for developing regulations with
improved monitoring. These materials may also include guidance and
tools for establishing emissions reductions credits and the economic
benefits associated with improved monitoring. As noted in section L
above, we also reaffirm our policy that effective regulations must
include certain elements that define applicable emissions limitations,
the testing and monitoring requirements, and compliance, reporting, and
corrective action obligations.
c. Comments and Responses
We expected to receive practical advice concerning improved
PM2.5 source emissions monitoring methods and field-tested
examples. Instead, commenters focused on (1) critiquing PM CEMS
technology (2) insisting that improving monitoring changes stringency
of existing rules and requires rulemaking, and (3) critiquing the
theoretical study linking emissions reductions with improved monitoring.
1. Currently Available PM CEMS for Monitoring Direct PM2.5 Emissions
Comment: Commenters noted that because currently available PM CEMS
measure filterable PM at stack conditions or at other elevated temperatures,
the instruments do not measure the condensable portion of PM2.5.
Response: We agree with this comment relative to PM CEMS in use to
date and the ability to detect condensable PM. PM CEMS as applied today
can be calibrated to measure filterable PM2.5 emissions with
very good sensitivity and repeatability. Note
[[Page 20657]]
that we are aware of a number of PM CEMS vendors developing devices
relying on much the same technology but modified to measure condensable
PM. Further, we are aware of at least one manufacturer offering a PM
CEMS applicable to stationary sources that also complies with ASTM
requirements for mobile source emissions monitoring. We also believe
that monitoring for filterable PM2.5 will be as important in
some cases as monitoring for condensable PM and that PM CEMS in use
today are markedly better at monitoring PM emissions than other
frequently used monitoring approaches.
We realize that PM CEMS represent just one of a range of monitoring
options that constitute improvements over the current monitoring. For
instance, we believe that improved monitoring would include replacing
current periodic VE measurements or daily recording of pressure drop of
fabric filters with continuous bag leak detectors. We know of projects
(e.g., ASTM committee work) for continuing the development of optical,
as well as electromagnetic, monitoring tools to increase sensitivity
and cost-effectiveness. Such monitoring would increase monitoring
frequency and would yield data much more closely related to and more
sensitive to control device operation than most currently applied
monitoring. To the extent that condensable PM control is critical in
implementing a regulation, we believe that monitoring must address that
need. We will continue to collect and also provide information on
source monitoring approaches that are improvements over current methods
in both frequency and representativeness relative to implementing
PM2.5 emissions control strategies.
2. Status of Guidance Relative to Regulations
Comment: A significant majority of commenters suggested that
improving monitoring in an existing regulation increases its stringency
and requires notice and comment rulemaking, not guidance. Just one
commenter suggested guidance could be developed and used.
Response: There are two aspects to the comments on this issue. One
is whether improved monitoring would change source operations. We agree
with the commenters that increasing the frequency of data collection or
providing data more directly related to the pollutant of concern with
improved monitoring could result in changes in how a facility is
operated relative to compliance. We disagree with commenters that such
changes in process operation resulting from improved monitoring
constitute an increase in a regulation's stringency with respect to
compliance. First, as mentioned in the preamble to the Credible
Evidence rule (62 FR 8326, February 24, 1997), an emissions standard's
required stringency is unaffected by the frequency of monitoring given
no decrease in averaging time or emissions limitation. Secondly, data
from improved monitoring will provide a facility operator better
information on control measure performance more quickly and allow for
reducing the duration and the number of periods that may lead to
compliance problems. Reducing the duration of excess emissions periods,
for example, with improved monitoring is not an increase in regulatory
stringency but a decrease in enforcement liability.
The second aspect to the comment is questioning whether we can
issue technical information about improved monitoring as guidance
without applying it to a Federal Register notice and comment process.
We disagree with commenters who believe that our developing and
disseminating technical resource information is limited to notice and
comment rulemaking. We note that making technical and other information
materials available to the public, states, and industry is an important
Agency function. There are many examples of the Agency dispensing such
information including the Monitoring Knowledge Base (http://cfpub.epa.gov
mkb/) that provides just such information on improved
monitoring. On the other hand, we agree with commenters that any
significant change to an existing regulation, including the addition of
new monitoring requirements, would be subject to notice and comment
rulemaking. To the extent that States determine the need for changing
existing or developing new regulations, public notice and comment
rulemaking is appropriate. Our role in developing technical resources
and information informing the states in developing those revised or new
regulations does not require, nor should be subject to the rulemaking
process. In that light, we recognize the value in obtaining and
responding to public comments and suggestions on informative technical
materials. Further, we believe rulemaking is not necessarily required
for source owners or operators who volunteer to participate in an
optional improved monitoring program, such as the one mentioned in the
proposal. That program seeks to provide SIP credits to States where
source owners or operators agree to improve their PM monitoring
approaches. We plan on continuing to prepare and offer non-regulatory
incentives for source owners and operators who volunteer to improve
existing monitoring.
3. Study of Improved Monitoring-Induced Emissions Reductions
Comment: Commenters recommended that the proposal's theoretical
study showing PM emissions reductions from the use of improved
monitoring needs to be validated with field data.
Response: We agree with commenters that one should base any costs
and benefits findings as well as validating the approach on available
data. To the extent that this applies to assessing the benefits of
emissions reductions achieved through improved monitoring, we requested
that commenters provide data or leads to other information or to other
alternatives that show how improved monitoring yields emissions
reductions and ways to quantify possible PM credits for SIPs. In fact,
we are disappointed that commenters failed to provide these data or
examples of other approaches. As resources allow, we will investigate
opportunities for field validation of the theoretical study, as well as
other means to offer incentives for use of improved monitoring.
N. Guidance Specific to Tribes
a. Background
The proposal set forth guidance for Tribes regarding various
aspects of air quality management, and this guidance remains largely
the same as described in the section below.
b. Final Rule
The 1998 Tribal Authority Rule (TAR) (40 CFR part 49), which
implements section 301(d) of the CAA, gives Tribes the option of
developing tribal implementation plans (TIPs). Specifically, the TAR
provides for the Tribes to be treated in the same manner as a State in
implementing sections of the CAA. However, Tribes are not required to
develop implementation plans. The EPA determined in the TAR that it was
inappropriate to treat Tribes in a manner similar to a State with
regard to specific plan submittal and implementation deadlines for
NAAQS-related requirements, including, but not limited to, such
deadlines in CAA sections 110(a)(1), 172(a)(2), 182, 187, and 191. (Add
footnote) See 40 CFR 49.4(a). In addition, EPA determined it was not
appropriate to treat tribes similarly to states with respect to
provisions of the CAA requiring as a condition of program approval the
demonstration of criminal enforcement
[[Page 20658]]
authority or providing for the delegation of such criminal enforcement
authority. See 40 CFR 49.4(g). To the extent a tribe is precluded from
asserting criminal enforcement authority, the Federal government will
exercise primary criminal enforcement responsibility. See 40 CFR 49.8.
In such circumstances, tribes seeking approval for CAA programs provide
potential investigative leads to an appropriate federal enforcement
agency. (end footnote)
If a Tribe elects to do a TIP, we will work with the Tribe to
develop an appropriate schedule which meets the needs of the Tribe, and
which does not interfere with the attainment of the NAAQS in other
jurisdictions. The Tribe developing a TIP can work with the EPA
Regional Office on the appropriateness of addressing RFP and other
substantive SIP requirements that may or may not be appropriate for the
Tribe's situation.
The TAR indicates that EPA is ultimately responsible for
implementing CAA programs in Indian country, as necessary and
appropriate, if Tribes choose not to implement those provisions. For
example, an unhealthy air quality situation in Indian country may
require EPA to develop a FIP to reduce emissions from sources on the
reservation. In such a situation, EPA, in consultation with the Tribe
and in consideration of their needs, would work to ensure that the
NAAQS are met as expeditiously as practicable. Likewise, if we
determine that sources in Indian country could interfere with a larger
nonattainment area meeting the NAAQS by its attainment date, we would
develop a FIP for those sources in consultation with the Tribe, as
necessary or appropriate.
The TAR also provides flexibility for the Tribe in the preparation
of a TIP to address the NAAQS. If a Tribe elects to develop a TIP, the
TAR offers flexibility to Tribes to identify and implement on a Tribe-
by-Tribe, case-by-case basis only those CAA programs or program
elements needed to address their specific air quality problems. In the
proposed Tribal rule, we described this flexible implementation
approach as a modular approach. Each Tribe may evaluate the particular
activities, including potential sources of air pollution within the
exterior boundaries of its reservation (or within non-reservation areas
for which it has demonstrated jurisdiction), which cause or contribute
to its air pollution problem. A Tribe may adopt measures for
controlling those sources of PM2.5-related emissions, as
long as the elements of the TIP are reasonably severable from the
package of elements that can be included in a whole TIP. A TIP must
include regulations designed to solve specific air quality problems for
which the Tribe is seeking EPA approval, as well as a demonstration
that the Tribal air agency has the authority from the Tribal government
to develop and run their program, the capability to enforce their
rules, and the resources to implement the program they adopt. In
addition, the Tribe must receive an eligibility determination from EPA
to be treated in the same manner as a State and to receive
authorization from EPA to run a CAA program.
The EPA would review and approve, where appropriate, these partial
TIPs as one step of an overall air quality plan to attain the NAAQS. A
Tribe may step in later to add other elements to the plan, or EPA may
step in to fill gaps in the air quality plan as necessary or
appropriate. In approving a TIP, we would evaluate whether the plan
interferes with the overall air quality plan for an area when Tribal
lands are part of a multi-jurisdictional area. Because many of the
nonattainment areas will include multiple jurisdictions, and in some
cases both Tribal and State jurisdictions, it is important for the
Tribes and the States to work together to coordinate their planning
efforts. States need to incorporate Tribal emissions in their base
emission inventories if Indian country is part of an attainment or
nonattainment area. Tribes and States need to coordinate their planning
activities as appropriate to ensure that neither is adversely affecting
attainment of the NAAQS in the area as a whole.
c. Comments and Responses
No public comments were received on this section.
O. Enforcement and Compliance
a. Background
The proposed rule included a discussion of the specific
requirements that must be addressed in order for SIP regulations to be
enforceable.
b. Final Rule
The final rule includes similar guidance on enforceable SIP
regulations, with some additional discussion about specific elements
that must be addressed regarding compliance testing and compliance
monitoring. (Note that enforceable SIP regulations may address these
key elements in different ways depending on the type of source category
being regulated.)
In general, for a SIP regulation to be enforceable, it must clearly
spell out which sources or source types are subject to its requirements
and what its requirements (e.g., emission limits, work practices, etc.)
are. The regulation also needs to specify the time frames within which
these requirements must be met, and must definitively state
recordkeeping and monitoring requirements appropriate to the type of
sources being regulated. The recordkeeping and monitoring requirements
must be sufficient to enable the State or EPA to determine whether the
source is complying with the emission limit on a continuous basis. An
enforceable regulation must also contain test procedures in order to
determine whether sources are in compliance.
Complete and effective regulations that ensure compliance with an
applicable emissions limit must include requirements for both
performance testing of emissions and ongoing monitoring of the
compliance performance of control measures. SIP regulations must
include the following critical elements of regulatory compliance testing:
? Indicator(s) of compliance--the pollutant or pollutants of
interest (e.g., filterable PM2.5 plus condensable
PM2.5) and the applicable measurable units for expressing
compliance (e.g., ng/J of heat input, lb/hr);
? Test method--reference to a specific EPA or other
published set of sample collection and analytical procedures, equipment
design and performance criteria, and the calculations providing data in
units of the indicator of compliance (see section II.L. below for
descriptions of available and potential improved test methods);
? Averaging time--the minimum length of each required test
run and the requirement to average the results of the test runs (e.g.,
three runs) representing a specified period of time (e.g., 8 hours);
and
? Frequency--the maximum time between conduct of emissions
or performance tests (e.g., within 30 days of facility start-up and
once each successive quarter, every 6-month period, yearly).
In order to be complete with regard to compliance monitoring
provisions, SIP regulations must include the following critical elements:
? Indicator(s) of performance--the parameter or parameters
measured or observed for demonstrating proper operation of the
pollution control measures or compliance with the applicable emissions
limitation or standard. Indicators of performance may include direct or
predicted emissions measurements, process or control device (and
capture system) operational
[[Page 20659]]
parametric values that correspond to compliance with efficiency or
emissions limits, and recorded findings of verification of work
practice activities, raw material or fuels pollutant content, or design
characteristics. Indicators may be expressed as a single maximum or
minimum value, a function of process variables (e.g., within a range of
pressure drops), a particular operational or work practice status
(e.g., a damper position, completion of a waste recovery task), raw
material or fuel pollutant content, or an interdependency between two
or more variables;
? Measurement technique--the means used to gather and record
information of or about the indicators of performance. The components
of the measurement technique include the detector type or analytical
method, location and installation specifications, inspection
procedures, and quality assurance and quality control measures.
Examples of measurement approaches include continuous emissions
monitoring systems, continuous opacity monitoring systems, continuous
parametric monitoring systems, performance testing, vendor or
laboratory analytical data, and manual inspections and data collection
that include making records of process conditions, raw materials or
fuel specifications, or work practices;
? Monitoring frequency--the number of times to obtain and
record monitoring data over a specified time interval. Examples of
monitoring frequencies include at least one data value every 15 minutes
for continuous emissions or parametric monitoring systems, at least
every 10 seconds for continuous opacity monitoring systems, upon
receipt or application of raw materials or fuel to the process, and at
least once per operating day (or week, month, etc.) for performance
testing, work practice verification, or equipment design inspections;
and
? Averaging time--the period over which to average and use
data to verify compliance with the emissions limitation or standard or
proper operation of the pollution control measure. Examples of
averaging time include a 3-hour average in units of the emissions
limitation, a 30-day rolling average emissions value, a daily average
of a control device operational parametric range, periodic (e.g.,
monthly, annual) average of raw materials or fuel pollutant content,
and an instantaneous alarm.
These regulatory elements are essential for effective
implementation of the rules and clear and enforceable applicable
requirements. We believe that approval of regulations implementing the
SIPs must ensure that these critical elements are present and clearly
defined to be approvable. We reiterate that the compliance obligations,
including emissions limits and other applicable requirements, must be
representative of and accountable to the assumptions used in the SIP
demonstration. This accountability includes the ability to transfer the
applicable regulatory requirements to an operating permit subject to
EPA and public review.
Under the Title V regulations, sources have an obligation to
include in their Title V permit applications all emissions for which
the source is major and all emissions of regulated air pollutants. The
definition of regulated air pollutant in 40 CFR 70.2 includes any
pollutant for which a NAAQS has been promulgated, which would include
both PM10 and PM2.5. To date, some permitted
entities have been using PM10 emissions as a surrogate for
PM2.5 emissions. Upon promulgation of this rule, EPA will no
longer accept the use of PM10 as a surrogate for
PM2.5. Thus, sources will be required to include their
PM2.5 emissions in their Title V permit applications, in any
corrections or supplements to these applications, and in applications
submitted upon modification and renewal.\52\ The degree of
quantification of PM2.5 emissions required will depend on
the types of determinations that a permitting authority needs to
address for a particular source, the requirements of title V, and the
informational needs and requirements of the particular State in
question. Sources must continue to describe their PM10
emissions in their applications as indicated above because the original
PM10 NAAQS remains in effect.
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\52\ See 40 CFR 70.5(c)(3)(i), 70.5(b), and 70.7(a)(1)(i); 40
CFR 71.5(c)(3)(i), 71.5(b), and 71.7(a)(1)(i).
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c. Comments and Responses
Comment: One commenter disagreed with language in the preamble to
the proposal regarding Title V permitting requirements and the
requirement to include various emissions information in title V permit
applications. As described in 40 CFR 70.5(c)(3)(i) and 71.5(c)(3)(i),
sources are required to include in their permit applications all
emissions for which the source is major and all emissions of regulated
air pollutants. In the preamble to the proposal, the EPA stated that in
the past some permitted entities have been using PM10
emissions as a surrogate for PM2.5 emissions in permit
applications, or in corrections or supplements to applications. The EPA
stated that upon promulgation of this rule, the EPA will no longer
accept the use of PM10 as a surrogate for PM2.5.
The commenter disagreed with language in the proposal stating that
sources would be required to detail or quantify PM2.5
emissions in permit applications, or in corrections or supplements to
applications. The commenter asserts that the inclusion of
PM2.5 emissions information is required in a Title V permit
application only if there is an applicable requirement in existence for
which the source's applicability is in question and cited to various
examples from the memorandum entitled ``White Paper for Streamlined
Development of Part 70 Permit Applications,'' from Lydia N. Wegman,
Deputy Director, Office of Air Quality Planning and Standards, to Air
Division Directors, Regions I-X, dated July 10, 1995.
Response: The commenter is concerned that as a result of this rule
all applications (including initial, modification, and renewal
applications) will need to include a quantification of PM2.5
emissions, and that a State will request that every source supplement
or correct any existing title V application in order to provide an
estimation of PM2.5 emissions at the source.
The EPA is not implying that this is the case. The degree of
quantification of PM2.5 emissions required in an application
(including an initial, modification, or renewal application), or in a
correction or supplement to an existing application, depends on the
types of determinations that a permitting authority needs to address
for a particular source, the requirements of title V, and the
informational needs and requirements of the particular State in
question. For example, if a source which emits PM2.5
emissions has submitted a title V application, but a draft permit has
not yet been issued, then the source is required to submit information
relative to the quantification of its PM2.5 emissions if
such information is needed or requested and it has not previously
submitted such information. See 40 CFR 70.5(b) and 71.5(b).
Circumstances necessitating the quantification of PM2.5
emissions and the submittal of this information include: (1)
Determining all of the pollutants for which a source is major; (2)
determining whether an applicable requirement or program applies, e.g.,
determining the applicability of a SIP requirement or a PSD or
nonattainment NSR program, etc.; or (3) determining what fees a source
owes a permitting
[[Page 20660]]
authority as a result of considering PM2.5 emissions.
In all circumstances, however, a State may require that a source
quantify its PM2.5 emissions information in an application,
supplement, or correction, even if it is not needed for the particular
determination at issue. The State, for example, may choose to obtain
this information for air quality planning purposes, developing emission
inventories, or for other purposes related to its air quality
management goals. Requesting such emissions information is an option
for any title V permitting authority.
The ``White Paper for Streamlined Development of Part 70 Permit
Applications,'' referenced by the commenter, was a confirmation of EPA
policy with respect to the fact that the specificity of emissions
quantification can vary significantly, depending on the circumstances
of a particular source. It is also important to note that this guidance
document is a statement regarding the range of discretion available to
permitting authorities in implementing the emissions quantification
requirement, not a restriction of that discretion to minimum practices.
Thus, States can implement this guidance document at their option,
either in part or in its entirety.
In summary, the purpose of the statements made in the preamble to
the proposal was to notify sources that as of the promulgation of this
final rule, the EPA will no longer accept the use of PM10
emissions information as a surrogate for PM2.5 emissions
information \53\ given that both pollutants are regulated by a National
Ambient Air Quality Standard and therefore are considered regulated air
pollutants. See the definition of regulated air pollutant in 40 CFR
70.2 and 71.2.\54\ The degree of quantification of PM2.5
emissions now required in an application (including an initial,
modification, or renewal application), or provided in a correction or
supplement to an existing application, will depend on the types of
determinations that a permitting authority needs to address for a
particular source, the requirements of title V, and the informational
needs and requirements of the particular State in question.
---------------------------------------------------------------------------
\53\ For background information on issues surrounding
implementation of the PM2.5 NAAQS, see the EPA memo
entitled ``Implementation of New Source Review Requirements in
PM2.5 Nonattainment Areas,'' from Stephen D. Page,
Director, Office of Air Quality Planning and Standards, to Regional
Air Directors, Regions I-X, dated April 5, 2005.
\54\ For background information on regulated air pollutants, see
the EPA memo entitled ``Definition of Regulated Air Pollutant for
Purposes of Title V,'' from Lydia N. Wegman, Deputy Director, Office
of Air Quality Planning and Standards, to Air Division Directors,
Regions I-X, dated April 26, 1993.
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P. Emergency Episodes
a. Background
In the proposal, we noted that subpart H of 40 CFR part 51
specifies requirements for SIPs to address emergency air pollution
episodes and for preventing air pollutant levels from reaching levels
determined to cause significant harm to the health of persons. We noted
that we anticipate proposing a separate rulemaking in the future to
update portions of that rule.
The preamble to the proposal
b. Final Rule
We have not yet proposed any rule revision related to emergency
episodes.
c. Comments and Responses
We received no comments on this section of the proposal.
Q. Ambient Monitoring
a. Background
Ambient air quality monitoring for PM2.5 plays an
important role in identifying areas violating the NAAQS, control
strategy development, and tracking progress to attainment. We indicated
in the proposal that States are required to monitor PM2.5
mass concentrations using Federal Reference Method devices to determine
compliance with the NAAQS.\55\ We did not propose any revisions to
current ambient monitoring requirements listed in 40 CFR part 58.
Currently, there are more than 1200 FRM monitors located across the
country. States will need to maintain monitors in designated nonattainment
areas in order to track progress toward attainment and ultimately determine
whether the area has attained the PM2.5 standards.
---------------------------------------------------------------------------
\55\ The PM2.5 monitoring regulations are located at
40 CFR part 58.
---------------------------------------------------------------------------
In addition to the FRM network, EPA and the States have also
deployed more than 250 speciation monitoring sites around the country
to sample for chemical composition of PM2.5. The data
provided from these speciation monitors are invaluable in identifying
contributing source categories and developing control strategies to
reach attainment. Source apportionment and other receptor modeling
techniques rely on the detailed data on species, ions, and other
compounds obtained from chemical analysis. Analyses of rural versus
urban sites to identify which PM2.5 components comprise the
``urban excess'' (urban minus rural levels) portion of PM2.5
mass also rely on data from speciation monitors. The EPA encourages
states to expand their data analysis efforts using the wealth of
information provided from the speciation monitoring network.
b. Final Rule
There is no change from the proposal. We are not promulgating any
additional monitoring requirements as part of this rulemaking. Revised
monitoring regulations were issued in 2006 along with the revised PM NAAQS.
c. Comments and Responses
There were no comments on this section.
III. Statutory and Executive Order Reviews
A. Executive Order 12866: Regulatory Planning and Review
Under section 3(f)(1) of Executive Order (EO) 12866 (58 FR 51735,
October 4, 1993), this action is an ``economically significant
regulatory action.'' Implementation of the PM2.5 NAAQS is
likely to have an annual effect on the economy of $100 million or more.
Accordingly, EPA submitted this action to the Office of Management and
Budget (OMB) for review under EO 12866 and any changes made in response
to OMB recommendations have been documented in the docket for this
action. For clarity, we note that the estimated costs and benefits of
implementing the 1997 PM2.5 NAAQS are not created by this
rule, because the Clean Air Act requires state implementation of the
1997 PM2.5 standards (through state development of plans
with enforceable requirements for sources) on a statutory timetable
regardless of whether EPA issues this rule interpreting the statutory
requirements. The rule reflects the statutory requirements.
As part of the ``Regulatory Impact Analysis for Particulate Matter
National Ambient Air Quality Standards (September 2006),'' EPA prepared
an assessment of the estimated costs and benefits associated with
attaining the 1997 PM2.5 NAAQS in 2015, incremental to
currently promulgated federal and state programs including for example
the Clean Air Interstate Rule, the Nonroad Diesel Rule, and other
programs. This analysis is included as Appendix A of the report and is
available in the docket for this action and on EPA's Web site at:
www.epa.gov/ttn/ecas/regdata/RIAs/Appendix%20A_2015%20Analysis.pdf.
This illustrative
[[Page 20661]]
analysis finds that the estimated monetized benefits of attaining the
1997 standards in 2015 are between $43 billion and $97 billion
annually, and the estimated monetized costs are $6.7 billion annually.
The RIA states: ``Note that because this analysis was intended to
compare costs and benefits of attaining alternative standards by fixed
dates, it did not attempt to identify for each designated
PM2.5 area measures that may be needed to meet subpart 1
Clean Air Act requirements, such as reasonably available measures and
attainment as expeditiously as practicable. It is expected that
additional costs and benefits will begin to accrue in earlier years as
states comply with these requirements.'' (RIA, p. 1-4)
B. Paperwork Reduction Act
The information collection requirements in this rule have been
submitted for approval to the Office of Management and Budget (OMB)
under the Paperwork Reduction Act, 44 U.S.C. 3501 et seq. In a separate
Federal Register notice published today, EPA is requesting comment on
the information collection requirements of this rule. The information
collection requirements are not enforceable until OMB approves them.
The data collected from the State or local air agency respondents
will include the required SIP elements prescribed in CAA sections 110
and part D, subpart 1 of title I for Implementation plans and the
requirements in this Implementation Rule (40 CFR 51.1000-51.1012). The
PM2.5 SIP will contain rules and other requirements designed
to achieve the NAAQS by the deadlines established under the CAA, and it
also contains a demonstration that the State's requirements will in
fact result in attainment. The SIP must meet the requirements in
subpart 1 to adopt RACM, RACT, and provide for RFP toward attainment
for the period prior to the area's attainment date.
The Agency anticipates additional administrative burden during the
3 year period of the ICR for State governments and the Agency of
630,000 hours and 69,300 hours, respectively. Fifty percent of the
hours are expended in the first year with the remainder evenly divided
between the second and third years of the ICR period. Tribes are not
required to conduct attainment demonstrations or submit the RFP, RACT,
or RACM requirements.
The present value of the total additional costs for State
government respondents is estimated at $33.4 million for the 3 year
period. On an equivalent annual basis that is $12.7 million per year
during the 3 year period of the ICR. The present value of the Agency
administrative cost burden is estimated at $3.7 million dollars for the
3 year period. This is equivalent to an equal annual stream of costs of
$1.4 million per year during the three year period. Burden means the
total time, effort, or financial resources expended by persons to
generate, maintain, retain, or disclose or provide information to or
for a Federal agency. This includes the time needed to review
instructions; develop, acquire, install, and utilize technology and
systems for the purposes of collecting, validating, and verifying
information, processing and maintaining information, and disclosing and
providing information; adjust the existing ways to comply with any
previously applicable instructions and requirements; train personnel to
be able to respond to a collection of information; search data sources;
complete and review the collection of information; and transmit or
otherwise disclose the information.
An agency may not conduct or sponsor, and a person is not required
to respond to a collection of information unless it displays a
currently valid OMB control number. The OMB control numbers for EPA's
regulations in 40 CFR are listed in 40 CFR part 9. When this ICR is
approved by OMB, the Agency will publish a technical amendment to 40
CFR part 9 in the Federal Register to display the OMB control number
for the approved information collection requirements contained in this
final rule.
C. Regulatory Flexibility Act
The Regulatory Flexibility Act (RFA) generally requires an agency
to prepare a regulatory flexibility analysis of any rule subject to
notice and comment rulemaking requirements under the Administrative
Procedure Act or any other statute unless the agency certifies that the
rule will not have a significant economic impact on a substantial
number of small entities. Small entities include small businesses,
small organizations, and small governmental jurisdictions.
For purposes of assessing the impacts of this final action on small
entities, small entity is defined as: (1) A small business as defined
by the Small Business Administration's (SBA) regulations at 13 CFR
121.201; (2) a small governmental jurisdiction that is a government of
a city, county, town, school district, or special district with a
population of less than 50,000; or (3) a small organization that is any
not-for-profit enterprise that is independently owned and operated and
is not dominant in its field.
After considering the economic impacts of this final rule on small
entities, I certify that this action will not have a significant
economic impact on a substantial number of small entities and it is not
necessary to prepare a regulatory flexibility analysis in conjunction
with this final rule. The final rule governing SIPs will not directly
impose any requirements on small entities. Rather, this rule interprets
the obligations established in the CAA for States to submit
implementation plans in order to attain the PM2.5 NAAQS.
D. Unfunded Mandates Reform Act
Title II of the Unfunded Mandates Reform Act of 1995 (UMRA), Public
Law 104-4, establishes requirements for Federal agencies to assess the
effects of their regulatory actions on State, local, and Tribal
governments and the private sector. Under section 202 of the UMRA, EPA
generally must prepare a written statement, including a cost-benefit
analysis, for proposed and final rules with ``Federal mandates'' that
may result in expenditures to State, local, and tribal governments, in
the aggregate, or to the private sector, of $100 million or more in any
1 year. Before promulgating an EPA rule for which a written statement
is needed, EPA is required by section 205 of the UMRA to identify and
consider a reasonable number of regulatory alternatives, and adopt the
least costly, most cost-effective or least burdensome alternative that
achieves the objectives of the rule. The provisions of section 205 do
not apply when they are inconsistent with applicable law. Moreover,
section 205 allows EPA to adopt an alternative other than the least
costly, most cost-effective or least burdensome alternative if the
Administrator publishes with the final rule an explanation why that
alternative was not adopted. Before EPA establishes any regulatory
requirements that may significantly or uniquely affect small
governments, including Tribal governments, it must have developed under
section 203 of the UMRA a small government agency plan. The plan must
provide for notifying potentially affected small governments, enabling
officials of affected small governments to have meaningful and timely
input in the development of EPA regulatory proposals with significant
Federal intergovernmental mandates, and informing, educating, and
advising small governments on compliance with the regulatory requirements.
This rule contains no Federal mandate that may result in expenditures
[[Page 20662]]
of $100 million or more for State, local, and Tribal governments, in
the aggregate, or the private sector in any 1 year. The estimated
administrative burden hours and costs associated with implementing the
PM2.5 NAAQS are estimated in the ICR for this rule. The
estimated costs presented there for States totals $33.4 million for a
three-year period. Thus, this rule is not subject to the requirements
of section 202 and 205 of the UMRA. The EPA consulted with governmental
entities affected by this rule and has determined that this rule
contains no regulatory requirements that may significantly or uniquely
affect small governments, including Tribal governments.
The CAA imposes the obligation for States to submit SIPs to
implement the PM2.5 NAAQS. In this rule, EPA is merely
providing an interpretation of those requirements. However, even if
this rule did establish an independent requirement for States to submit
SIPs, it is questionable whether a requirement to submit a SIP revision
would constitute a Federal mandate in any case. The obligation for a
State to submit a SIP that arises out of section 110 and section 172
(part D) of the CAA is not legally enforceable by a court of law, and
at most is a condition for continued receipt of highway funds.
Therefore, it is possible to view an action requiring such a submittal
as not creating any enforceable duty within the meaning of section
421(5)(9a)(I) of UMRA (2 U.S.C. 658(a)(I)). Even if it did, the duty
could be viewed as falling within the exception for a condition of
Federal assistance under section 421(5)(a)(i)(I) of UMRA (2 U.S.C.
658(5)(a)(i)(I)).
E. Executive Order 13132: Federalism
Executive Order 13132, entitled ``Federalism'' (64 FR 43255, August
10, 1999), requires EPA to develop an accountable process to ensure
``meaningful and timely input by State and local officials in the
development of regulatory policies that have Federalism implications.''
``Policies that have Federalism implications'' is defined in the
Executive Order to include regulations that have ``substantial direct
effects on the States, on the relationship between the national
government and the States, or on the distribution of power and
responsibilities among the various levels of government.''
At the time of proposal, EPA concluded that the proposed rule would
not have any federalism implications. The EPA stated that the proposed
rule would not have substantial direct effects on the States, on the
relationship between the national government and the States, or on the
distribution of power and responsibilities among the various levels of
government, as specified in Executive Order 13132. The CAA establishes
the scheme whereby States take the lead in developing plans to meet the
NAAQS. This rule clarifies the statutory obligations of States in
implementing the PM2.5 NAAQS. However, EPA recognized that
States would have a substantial interest in this rule and any
corresponding revisions to associated SIP requirements.
Therefore, in the spirit of Executive Order 13132, and consistent
with EPA policy to promote communications between EPA and State and
local governments, EPA held a number of calls with representatives of
State and local air pollution control agencies and hosted a public
hearing in Washington, DC in November 2005. The EPA considered the
comments from State and local governments in developing the final rule.
EPA concludes that this final rule does not have federalism
implications, for the reasons proposed. The final rule will not modify
the relationship of the States and EPA for purposes of developing
programs to implement the NAAQS. As noted above in section D on UMRA,
this rule does not impose significant costs on State and local
governments. (EPA estimates the costs to States to implement the
PM2.5 NAAQS to be $33.4 million.) Thus, Executive Order
13132 does not apply to this rule.
F. Executive Order 13175: Consultation and Coordination With Indian
Tribal Governments
Executive Order 13175, entitled ``Consultation and Coordination
with Indian Tribal Governments'' (59 FR 22951, November 9, 2000),
requires EPA to develop an accountable process to ensure ``meaningful
and timely input by Tribal officials in the development of regulatory
policies that have Tribal implications.'' This final rule does not have
``Tribal implications'' as defined in Executive Order 13175. This rule
concerns the requirements for State and tribal implementation plans for
attaining the PM2.5 air quality standards. The CAA provides
for States to develop plans to regulate emissions of air pollutants
within their jurisdictions. The Tribal Air Rule (TAR) under the CAA
gives Tribes the opportunity to develop and implement CAA programs such
as programs to attain and maintain the PM2.5 NAAQS, but it
leaves to the discretion of the Tribe the decision of whether to
develop these programs and which programs, or appropriate elements of a
program, they will adopt.
Although Executive Order 13175 does not apply to this rule, EPA did
reach out to Tribal leaders and environmental staff in developing this
rule. From 2001-2004, the EPA supported a National Designations
Workgroup to provide a forum for tribal professionals to give input to
the designations process. In 2006, EPA supported a national ``Tribal
Air call'' which provides an open forum for all Tribes to voice
concerns to EPA about the NAAQS implementation process, including the
PM2.5 NAAQS. In these meetings, EPA briefed call
participants and Tribal environmental professionals gave input as the
rule was under development. Furthermore, in December 2005, EPA sent
individualized letters to all federally recognized Tribes about the
proposal to give Tribal leaders the opportunity for consultation.
This final rule does not have Tribal implications as defined by
Executive Order 13175. It does not have a substantial direct effect on
one or more Indian Tribes, since no Tribe has implemented a CAA program
to attain the PM2.5 NAAQS at this time. The EPA notes that
even if a Tribe were implementing such a plan at this time, while the
rule might have Tribal implications with respect to that Tribe, it
would not impose substantial direct costs upon it, nor would it preempt
Tribal law.
Furthermore, this rule does not affect the relationship or
distribution of power and responsibilities between the Federal
government and Indian Tribes. The CAA and the TAR establish the
relationship of the Federal government and Tribes in developing plans
to attain the NAAQS, and this rule does nothing to modify that
relationship. As this rule does not have Tribal implications, Executive
Order 13175 does not apply.
G. Executive Order 13045: Protection of Children From Environmental
Health and Safety Risks
EO 13045, ``Protection of Children from Environmental Health and
Safety Risks,'' (62 FR 19885, April 23, 1997) applies to any rule that
(1) Is determined to be ``economically significant'' as defined under
Executive Order 12866, and (2) concerns an environmental health or
safety risk that EPA has reason to believe may have disproportionate
effect on children. If the regulatory action meets both criteria, the
Agency must evaluate the environmental health or safety effects of the
planned rule on children, and explain why the planned regulation is
preferable to other potentially effective and reasonably feasible
alternatives considered by the Agency. This final
[[Page 20663]]
rule is subject to EO 13045 because it is economically significant as
defined in EO 12866, and we believe that the environmental health risk
addressed by this action may have a disproportionate effect on
children. This rule implements a previously promulgated health-based
Federal standard--the PM2.5 NAAQS \56\. The NAAQS constitute
uniform, national standards for PM pollution; these standards are
designed to protect public health with an adequate margin of safety, as
required by CAA section 109. However, the protection offered by these
standards may be especially important for children because children,
along with other sensitive population subgroups such as the elderly and
people with existing heart or lung disease, are potentially susceptible
to health effects resulting from PM exposure. Because children are
considered a potentially susceptible population, we have carefully
evaluated the environmental health effects of exposure to PM pollution
among children. These effects and the size of the population affected
are summarized in section 9.2.4 of the Criteria Document and section
3.5 of the Staff Paper.
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\56\ See 62 FR 38652-38760, National Ambient Air Quality
Standards for Particulate Matter, Final Rule; also 40 CFR part 50.
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H. Executive Order 13211: Actions That Significantly Affect Energy
Supply, Distribution, or Use
This final rule is not a ``significant energy action'' as defined
in Executive Order 13211, ``Actions That Significantly Affect Energy
Supply, Distribution, or Use,'' (66 FR 28355, May 22, 2001) because it
is not likely to have a significant adverse effect on the supply,
distribution, or use of energy. This rule is not a ``significant energy
action,'' because it does not establish requirements that directly
affect the general public and the public and private sectors, but,
rather, interprets the statutory requirements that apply to States in
preparing their SIPs. The SIPs themselves will likely establish
requirements that directly affect the general public, and the public
and private sectors.
I. National Technology Transfer Advancement Act
Section 12(d) of the National Technology Transfer Advancement Act
of 1995 (``NTTAA''), Public Law No. 104-113, section 12(d) (15 U.S.C.
272 note) directs EPA to use voluntary consensus standards (VCS) in its
regulatory activities unless to do so would be inconsistent with
applicable law or otherwise impractical. Voluntary consensus standards
are technical standards (e.g., materials specifications, test methods,
sampling procedures, and business practices) that are developed or
adopted by VCS bodies. The NTTAA directs EPA to provide Congress,
through OMB, explanations when the Agency decides not to use available
and applicable VCS.
This final rulemaking does not involve technical standards.
Therefore, EPA is not considering the use of any VCS. The EPA will
encourage the States and Tribes to consider the use of such standards,
where appropriate, in the development of their implementation plans.
J. Executive Order 12898: Federal Actions To Address Environmental
Justice in Minority Populations and Low-Income Populations
EO 12898 (59 FR 7629 (Feb. 16, 1994) establishes Federal executive
policy on environmental justice. Its main provision directs Federal
agencies, to the greatest extent practicable and permitted by law, to
make environmental justice part of their mission by identifying and
addressing, as appropriate, disproportionately high and adverse human
health or environmental effects of their programs, policies and
activities on minority populations and low-income populations in the
United States.
The EPA has determined that the final rule should not have
disproportionately high and adverse human health or environmental
effects on minority or low-income populations because it increases the
level of environmental protection for all affected populations without
having any disproportionately high and adverse human health or
environmental effects on any population, including any minority or low-
income population. The health and environmental risks associated with
fine particles were considered in the establishment of the
PM2.5 NAAQS. The level is designed to be protective with an
adequate margin of safety. This final rule provides a framework for
improving environmental quality and reducing health risks for areas
that may be designated nonattainment.
K. Congressional Review Act
The Congressional Review Act, 5 U.S.C. 801 et seq., as added by the
Small Business Regulatory Enforcement Fairness Act of 1996, generally
provides that before a rule may take effect, the agency promulgating
the rule must submit a rule report, which includes a copy of the rule,
to each House of the Congress and to the Comptroller General of the
United States. The EPA will submit a report containing the rule and
other required information to the U.S. Senate, the U.S. House of
Representatives, and the Comptroller General of the United States prior
to publication of the rule in the Federal Register. A Major rule cannot
take effect until 60 days after it is published in the Federal
Register. This action is a ``major rule'' as defined by 5 U.S.C.
804(2). This rule will be effective June 25, 2007.
L. Petitions for Judicial Review
Under section 307(b)(1) of the Act, petitions for judicial review
of this action must be filed in the United States Court of Appeals for
the District of Columbia Circuit by June 25, 2007. Filing a petition
for reconsideration by the Administrator of this final rule does not
affect the finality of this rule for the purposes of judicial review
nor does it extend the time within which a petition for judicial review
may be filed, and shall not postpone the effectiveness of such rule or
action. This action may not be challenged later in proceedings to
enforce its requirements. See Act section 307(b)(2).
M. Judicial Review
Under sections 307(d)(1)(E) and 307(d)(1)(V) of the CAA, the
Administrator determines that this action is subject to the provisions
of section 307(d). Section 307(d)(1)(V) provides that the provisions of
section 307(d) apply to ``such other actions as the Administrator may
determine.'' While the Administrator did not make this determination
earlier, the Administrator believes that all of the procedural
requirements, e.g., docketing, hearing and comment periods, of section
307(d) have been complied with during the course of this rulemaking.
IV. Statutory Authority
The statutory authority for this action is provided by 42 U.S.C.
7401, 7408, 7410, 7501-7509a, and 7601(a)(1). This notice is also
subject to 307(d) of the CAA (42 U.S.C. 7407(d)).
List of Subjects in 40 CFR Part 51
Administrative practice and procedure, Air pollution control,
Intergovernmental relations, Nitrogen dioxide, Ozone, Particulate
matter, Sulfur oxides, Transportation, Volatile organic compound.
Dated: March 29, 2007.
Stephen L. Johnson,
Administrator.
? For the reasons set out in the preamble, title 40, chapter I of the Code
[[Page 20664]]
of Federal Regulations is amended as follows:
? 1. The authority citation for part 51 continues to read as follows:
Authority: 23 U.S.C. 101; 42 U.S.C. 7401-7671q.
? 2. A new Subpart Z is added to read as follows:
Subpart Z--Provisions for Implementation of PM2.5 National Ambient
Air Quality Standards
Sec.
51.1000 Definitions.
51.1001 Applicability of part 51.
51.1002 Submittal of State implementation plan.
51.1003 [Reserved]
51.1004 Attainment dates.
51.1005 One-year extensions of the attainment date.
51.1006 Redesignation to nonattainment following initial
designations for the PM2.5 NAAQS.
51.1007 Attainment demonstration and modeling requirements.
51.1008 Emission inventory requirements for the PM2.5 NAAQS.
51.1009 Reasonable further progress (RFP) requirements.
51.1010 Requirements for reasonably available control technology
(RACT) and reasonably available control measures (RACM).
51.1011 Requirements for mid-course review.
51.1012. Requirements for contingency measures.
Sec. 51.1000 Definitions.
The following definitions apply for purposes of this subpart. Any
term not defined herein shall have the meaning as defined in 40 CFR 51.100.
Act means the Clean Air Act as codified at 42 U.S.C. 7401-7671q. (2003).
Attainment date means the date by which an area, under an approved
State implementation plan, is required to attain the PM2.5
NAAQS (based on the average of three consecutive years of ambient air
quality data).
Baseline year inventory for the RFP plan is the emissions inventory
for the year also used as the base year for the attainment demonstration.
Benchmark RFP plan means the reasonable further progress plan that
requires generally linear emission reductions in pollutants from the
baseline emissions year through the milestone inventory year.
Date of designation means the effective date of the
PM2.5 area designation as promulgated by the Administrator.
Direct PM2.5 emissions means solid particles emitted
directly from an air emissions source or activity, or gaseous emissions
or liquid droplets from an air emissions source or activity which
condense to form particulate matter at ambient temperatures. Direct
PM2.5 emissions include elemental carbon, directly emitted
organic carbon, directly emitted sulfate, directly emitted nitrate, and
other inorganic particles (including but not limited to crustal
material, metals, and sea salt).
Existing control measure means any Federally enforceable national,
State, or local control measure that has been approved in the SIP and
that results in reductions in emissions of PM2.5 or
PM2.5 precursors in a nonattainment area.
Full implementation inventory is the projected RFP emission
inventory for the year preceding the attainment date, representing a
level of emissions that demonstrates attainment.
Milestone year inventory is the projected RFP emission inventory
for the applicable RFP milestone year (i.e. 2009 and, where applicable,
2012).
PM2.5 NAAQS means the particulate matter national
ambient air quality standards (annual and 24-hour) codified at 40 CFR 50.7.
PM2.5 design value for a nonattainment area is the
highest of the three-year average concentrations calculated for the
monitors in the area, in accordance with 40 CFR part 50, appendix N.
PM2.5 attainment plan precursor means S02 and
those other PM2.5 precursors emitted by sources in the State
which the State must evaluate for emission reduction measures to be
included in its PM2.5 nonattainment area or maintenance area
plan.
PM2.5 precursor means those air pollutants other than
PM2.5 direct emissions that contribute to the formation of
PM2.5. PM2.5 precursors include S02,
NOX, volatile organic compounds, and ammonia.
Reasonable further progress (RFP) means the incremental emissions
reductions toward attainment required under sections 172(c)(2) and 171(1).
Subpart 1 means the general attainment plan requirements found in
subpart 1 of part D of title I of the Act.
Sec. 51.1001 Applicability of part 51.
The provisions in subparts A through X of this part apply to areas
for purposes of the PM2.5 NAAQS to the extent they are not
inconsistent with the provisions of this subpart.
Sec. 51.1002 Submittal of State implementation plan.
(a) For any area designated by EPA as nonattainment for the
PM2.5 NAAQS, the State must submit a State implementation
plan satisfying the requirements of section 172 of the Act and this
subpart to EPA by the date prescribed by EPA which will be no later
than 3 years from the date of designation.
(b) The State must submit a plan consistent with the requirements
of section 110(a)(2) of the Act unless the State already has fulfilled
this obligation for the purposes of implementing the PM2.5 NAAQS.
(c) Pollutants contributing to fine particle concentrations. The
State implementation plan must identify and evaluate sources of
PM2.5 direct emissions and PM2.5 attainment plan
precursors in accordance with Sec. Sec. 51.1009 and 51.1010. After
January 1, 2011, for purposes of establishing emissions limits under
51.1009 and 51.1010, States must establish such limits taking into
consideration the condensable fraction of direct PM2.5
emissions. Prior to this date, States are not prohibited from
establishing source emission limits that include the condensable
fraction of direct PM2.5.
(1) The State must address sulfur dioxide as a PM2.5
attainment plan precursor and evaluate sources of SO2
emissions in the State for control measures.
(2) The State must address NOX as a PM2.5
attainment plan precursor and evaluate sources of NOX
emissions in the State for control measures, unless the State and EPA
provide an appropriate technical demonstration for a specific area
showing that NOX emissions from sources in the State do not
significantly contribute to PM2.5 concentrations in the
nonattainment area.
(3) The State is not required to address VOC as a PM2.5
attainment plan precursor and evaluate sources of VOC emissions in the
State for control measures, unless:
(i) the State provides an appropriate technical demonstration for a
specific area showing that VOC emissions from sources in the State
significantly contribute to PM2.5 concentrations in the
nonattainment area, and such demonstration is approved by EPA; or
(ii) The EPA provides such a technical demonstration.
(4) The State is not required to address ammonia as a
PM2.5 attainment plan precursor and evaluate sources of
ammonia emissions from sources in the State for control measures, unless:
(i) The State provides an appropriate technical demonstration for a
specific area showing that ammonia emissions from sources in the State
significantly contribute to PM2.5 concentrations in the
[[Page 20665]]
nonattainment area, and such demonstration is approved by EPA; or
(ii) The EPA provides such a technical demonstration.
(5) The State must submit a demonstration to reverse any
presumption in this rule for a PM2.5 precursor with respect
to a particular nonattainment area, if the administrative record
related to development of its SIP shows that the presumption is not
technically justified for that area.
Sec. 51.1003 [Reserved]
Sec. 51.1004 Attainment dates.
(a) Consistent with section 172(a)(2)(A) of the Act, the attainment
date for an area designated nonattainment for the PM2.5
NAAQS will be the date by which attainment can be achieved as
expeditiously as practicable, but no more than five years from the date
of designation. The Administrator may extend the attainment date to the
extent the Administrator determines appropriate, for a period no
greater than 10 years from the date of designation, considering the
severity of nonattainment and the availability and feasibility of
pollution control measures.
(b) In the SIP submittal for each of its nonattainment areas, the
State must submit an attainment demonstration justifying its proposed
attainment date. For each nonattainment area, the Administrator will
approve an attainment date at the same time the Administrator approves
the attainment demonstration for the area, consistent with the
attainment date timing provision of section 172(a)(2)(A) and paragraph
(a) of this section.
(c) Upon a determination by EPA that an area designated
nonattainment for the PM2.5 NAAQS has attained the standard,
the requirements for such area to submit attainment demonstrations and
associated reasonably available control measures, reasonable further
progress plans, contingency measures, and other planning SIPs related
to attainment of the PM2.5 NAAQS shall be suspended until
such time as: the area is redesignated to attainment, at which time the
requirements no longer apply; or EPA determines that the area has
violated the PM2.5 NAAQS, at which time the area is again
required to submit such plans.
Sec. 51.1005 One-year extensions of the attainment date.
(a) Pursuant to section 172(a)(2)(C)(ii) of the Act, a State with
an area that fails to attain the PM2.5 NAAQS by its
attainment date may apply for an initial 1-year attainment date
extension if the State has complied with all requirements and
commitments pertaining to the area in the applicable implementation
plan, and:
(1) For an area that violates the annual PM2.5 NAAQS as
of its attainment date, the annual average concentration for the most
recent year at each monitor is 15.0 [mu]g/m3 or less
(calculated according to the data analysis requirements in 40 CFR part
50, appendix N).
(2) For an area that violates the 24-hour PM2.5 NAAQS as
of its attainment date, the 98th percentile concentration for the most
recent year at each monitor is 65 [mu]g/m3 or less
(calculated according to the data analysis requirements in 40 CFR part
50, appendix N).
(b) An area that fails to attain the PM2.5 NAAQS after
receiving a 1-year attainment date extension may apply for a second 1-
year attainment date extension pursuant to section 172(a)(2)(C)(ii) if
the State has complied with all requirements and commitments pertaining
to the area in the applicable implementation plan, and:
(1) For an area that violates the annual PM2.5 NAAQS as
of its attainment date, the two-year average of annual average
concentrations at each monitor, based on the first extension year and
the previous year, is 15.0 [mu]g/m3 or less (calculated
according to the data analysis requirements in 40 CFR part 50, appendix N).
(2) For an area that violates the 24-hour PM2.5 NAAQS as
of its attainment date, the two-year average of annual 98th percentile
concentrations at each monitor, based on the first extension year and
the previous year, is 65 [mu]g/m3 or less (calculated
according to the data analysis requirements in 40 CFR part 50, appendix N).
Sec. 51.1006 Redesignation to nonattainment following initial
designations for the PM2.5 NAAQS.
Any area that is initially designated ``attainment/unclassifiable''
for the PM2.5 NAAQS may be subsequently redesignated to
nonattainment if ambient air quality data in future years indicate that
such a redesignation is appropriate. For any such area that is
redesignated to nonattainment for the PM2.5 NAAQS, any
absolute, fixed date that is applicable in connection with the
requirements of this part is extended by a period of time equal to the
length of time between the effective date of the initial designation
for the PM2.5 NAAQS and the effective date of redesignation,
except as otherwise provided in this subpart.
Sec. 51.1007 Attainment demonstration and modeling requirements.
(a) For any area designated as nonattainment for the
PM2.5 NAAQS, the State must submit an attainment
demonstration showing that the area will attain the annual and 24-hour
standards as expeditiously as practicable. The demonstration must meet
the requirements of Sec. 51.112 and Appendix W of this part and must
include inventory data, modeling results, and emission reduction
analyses on which the State has based its projected attainment date.
The attainment date justified by the demonstration must be consistent
with the requirements of Sec. 51.1004(a). The modeled strategies must
be consistent with requirements in Sec. 51.1009 for RFP and in Sec.
51.1010 for RACT and RACM. The attainment demonstration and supporting
air quality modeling should be consistent with EPA's PM2.5
modeling guidance.
(b) Required time frame for obtaining emissions reductions. For
each nonattainment area, the State implementation plan must provide for
implementation of all control measures needed for attainment as
expeditiously as practicable, but no later than the beginning of the
year prior to the attainment date. Consistent with section 172(c)(1) of
the Act, the plan must provide for implementation of all RACM and RACT
as expeditiously as practicable. The plan also must include RFP
milestones in accordance with Sec. 51.1009, and control measures
needed to meet these milestones, as necessary.
Sec. 51.1008 Emission inventory requirements for the PM2.5 NAAQS.
(a) For purposes of meeting the emission inventory requirements of
section 172(c)(3) of the Act for nonattainment areas, the State shall,
no later than three years after designation:
(1) Submit to EPA Statewide emission inventories for direct
PM2.5 emissions and emissions of PM2.5
precursors. For purposes of defining the data elements for these
inventories, the PM2.5 and PM2.5 precursor-relevant
data element requirements under subpart A of this part shall apply.
(2) Submit any additional emission inventory information needed to
support an attainment demonstration and RFP plan ensuring expeditious
attainment of the annual and 24-hour PM2.5 standards.
(b) For inventories required for submission under paragraph (a) of
this section, a baseline emission inventory is required for the
attainment demonstration required under Sec. 51.1007 and for meeting
RFP requirements
[[Page 20666]]
under Sec. 51.1009. As determined on the date of designation, the base
year for this inventory shall be the most recent calendar year for
which a complete inventory was required to be submitted to EPA pursuant
to subpart A of this part. The baseline emission inventory for calendar
year 2002 or other suitable year shall be used for attainment planning
and RFP plans for areas initially designated nonattainment for the
PM2.5 NAAQS in 2004-2005.
Sec. 51.1009 Reasonable further progress (RFP) requirements.
(a) Consistent with section 172(c)(2) of the Act, State
implementation plans for areas designated nonattainment for the
PM2.5 NAAQS must demonstrate reasonable further progress as
provided in Sec. 51.1009(b) through (h).
(b) If the State submits to EPA an attainment demonstration and
State implementation plan for an area which demonstrates that it will
attain the PM NAAQS within five years of the date of designation, the
State is not required to submit a separate RFP plan. Compliance with
the emission reduction measures in the attainment demonstration and
State implementation plan will meet the requirements for achieving
reasonable further progress for the area.
(c) For any area for which the State submits to EPA an approvable
attainment demonstration and State implementation plan that
demonstrates the area needs an attainment date of more than five years
from the date of designation, the State also must submit an RFP plan.
The RFP plan must describe the control measures that provide for
meeting the reasonable further progress milestones for the area, the
timing of implementation of those measures, and the expected reductions
in emissions of direct PM2.5 and PM2.5 attainment
plan precursors. The RFP plan is due to EPA within three years of the
date of designation.
(1) For any State that submits to EPA an approvable attainment
demonstration and State implementation plan justifying an attainment
date of more than five and less than nine years from the date of
designation, the RFP plan must include 2009 emissions milestones for
direct PM2.5 and PM2.5 attainment plan precursors
demonstrating that reasonable further progress will be achieved for the
2009 emissions year.
(2) For any area that submits to EPA an approvable attainment
demonstration and State implementation plan justifying an attainment
date of nine or ten years from the date of designation, the RFP plan
must include 2009 and 2012 emissions milestones for direct
PM2.5 and PM2.5 attainment plan precursors
demonstrating that reasonable further progress will be achieved for the
2009 and 2012 emissions years.
(d) The RFP plan must demonstrate that in each applicable milestone
year, emissions will be at a level consistent with generally linear
progress in reducing emissions between the base year and the attainment
year.
(e) For a multi-State nonattainment area, the RFP plans for each
State represented in the nonattainment area must demonstrate RFP on the
basis of common multi-State inventories. The States within which the
area is located must provide a coordinated RFP plan. Each State in a
multi-State nonattainment area must ensure that the sources within its
boundaries comply with enforceable emission levels and other
requirements that in combination with the reductions planned in other
state(s) will provide for attainment as expeditiously as practicable
and demonstrate reasonable further progress.
(f) In the benchmark RFP plan, the State must identify direct
PM2.5 emissions and PM2.5 attainment plan
precursors regulated under the PM2.5 attainment plan and
specify target emission reduction levels to be achieved during the
milestone years. In developing the benchmark RFP plan, the State must
develop emission inventory information for the geographic area included
in the plan and conduct the following calculations:
(1) For direct PM2.5 emissions and each PM2.5
attainment plan precursor addressed in the attainment strategy, the
full implementation reduction is calculated by subtracting the full
implementation inventory from the baseline year inventory.
(2) The ``milestone date fraction'' is the ratio of the number of
years from the baseline year to the milestone inventory year divided by
the number of years from the baseline year to the full implementation year.
(3) For direct PM2.5 emissions and each PM2.5
attainment plan precursor addressed in the attainment strategy, a
benchmark emission reduction is calculated by multiplying the full
implementation reduction by the milestone date fraction.
(4) The benchmark emission level in the milestone year is
calculated for direct PM2.5 emissions and each
PM2.5 attainment plan precursor by subtracting the benchmark
emission reduction from the baseline year emission level. The benchmark
RFP plan is defined as a plan that achieves benchmark emission levels
for direct PM2.5 emissions and each PM2.5 attainment
plan precursor addressed in the attainment strategy for the area.
(5) In comparing inventories between baseline and future years for
direct PM2.5 emissions and each PM2.5 attainment
plan precursor, the inventories must be derived from the same
geographic area. The plan must include emissions estimates for all
types of emitting sources and activities in the geographic area from
which the emission inventories for direct PM2.5 emissions
and each PM2.5 attainment plan precursor addressed in the
plan are derived.
(6) For purposes of establishing motor vehicle emissions budgets
for transportation conformity purposes (as required in 40 CFR part 93)
for a PM2.5 nonattainment area, the State shall include in
its RFP submittal an inventory of on-road mobile source emissions in
the nonattainment area.
(g) The RFP plan due three years after designation must demonstrate
that emissions for the milestone year are either:
(1) At levels that are roughly equivalent to the benchmark emission
levels for direct PM2.5 emissions and each PM2.5
attainment plan precursor to be addressed in the plan; or
(2) At levels included in an alternative scenario that is projected
to result in a generally equivalent improvement in air quality by the
milestone year as would be achieved under the benchmark RFP plan.
(h) The equivalence of an alternative scenario to the corresponding
benchmark plan must be determined by comparing the expected air quality
changes of the two scenarios at the design value monitor location. This
comparison must use the information developed for the attainment plan
to assess the relationship between emissions reductions of the direct
PM2.5 emissions and each PM2.5 attainment plan
precursor addressed in the attainment strategy and the ambient air
quality improvement for the associated ambient species.
Sec. 51.1010 Requirements for reasonably available control technology
(RACT) and reasonably available control measures (RACM).
(a) For each PM2.5 nonattainment area, the State shall
submit with the attainment demonstration a SIP revision demonstrating
that it has adopted all reasonably available control measures
(including RACT for stationary sources) necessary to demonstrate
attainment as expeditiously as practicable and to meet any RFP
requirements. The SIP revision shall contain the list of the potential
measures considered by the State, and
[[Page 20667]]
information and analysis sufficient to support the State's judgment
that it has adopted all RACM, including RACT.
(b) In determining whether a particular emission reduction measure
or set of measures must be adopted as RACM under section 172(c)(1) of
the Act, the State must consider the cumulative impact of implementing
the available measures. Potential measures that are reasonably
available considering technical and economic feasibility must be
adopted as RACM if, considered collectively, they would advance the
attainment date by one year or more.
Sec. 51.1011 Requirements for mid-course review.
(a) Any State that submits to EPA an approvable attainment plan for
a PM2.5 nonattainment area justifying an attainment date of
nine or ten years from the date of designation also must submit to EPA
a mid-course review six years from the date of designation.
(b) The mid-course review for an area must include:
(1) A review of emissions reductions and progress made in
implementing control measures to reduce emissions of direct
PM2.5 and PM2.5 attainment plan precursors
contributing to PM2.5 concentrations in the area;
(2) An analysis of changes in ambient air quality data for the area;
(3) Revised air quality modeling analysis to demonstrate attainment;
(4) Any new or revised control measures adopted by the State, as
necessary to ensure attainment by the attainment date in the approved
SIP of the nonattainment area.
Sec. 51.1012 Requirement for contingency measures.
Consistent with section 172(c)(9) of the Act, the State must submit
in each attainment plan specific contingency measures to be undertaken
if the area fails to make reasonable further progress, or fails to
attain the PM2.5 NAAQS by its attainment date. The
contingency measures must take effect without significant further
action by the State or EPA.
[FR Doc. E7-6347 Filed 4-24-07; 8:45 am]
BILLING CODE 6560-50-P
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