Control of Emissions of Air Pollution From Locomotive Engines and Marine Compression-Ignition Engines Less Than 30 Liters per Cylinder

[Federal Register: April 3, 2007 (Volume 72, Number 63)]
[Proposed Rules]
[Page 15937-15986]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]
[DOCID:fr03ap07-24]
[[Page 15938]]

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ENVIRONMENTAL PROTECTION AGENCY
40 CFR Parts 92, 94, 1033, 1039, 1042, 1065 and 1068
[EPA-HQ-OAR-2003-0190; FRL-8285-5]
RIN 2006-AM06

Control of Emissions of Air Pollution From Locomotive Engines and
Marine Compression-Ignition Engines Less Than 30 Liters per Cylinder

AGENCY: Environmental Protection Agency (EPA).
ACTION: Proposed rule.

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SUMMARY: Locomotives and marine diesel engines are important
contributors to our nation's air pollution today. These sources are
projected to continue to generate large amounts of particulate matter
(PM) and nitrogen oxides (NO_X) emissions that contribute to
nonattainment of the National Ambient Air Quality Standards (NAAQS) for
PM_2.5 and ozone across the United States. The emissions of
PM and ozone precursors from these engines are associated with serious
public health problems including premature mortality, aggravation of
respiratory and cardiovascular disease, aggravation of existing asthma,
acute respiratory symptoms, chronic bronchitis, and decreased lung
function. In addition, emissions from locomotives and marine diesel
engines are of particular concern, as diesel exhaust has been
classified by EPA as a likely human carcinogen.
EPA is proposing a comprehensive program to dramatically reduce
emissions from locomotives and marine diesel engines. It would apply
new exhaust emission standards and idle reduction requirements to
diesel locomotives of all types--line-haul, switch, and passenger. It
would also set new exhaust emission standards for all types of marine
diesel engines below 30 liters per cylinder displacement. These include
marine propulsion engines used on vessels from recreational and small
fishing boats to super-yachts, tugs and Great Lakes freighters, and
marine auxiliary engines ranging from small gensets to large generators
on ocean-going vessels. The proposed program includes a set of near-
term emission standards for newly-built engines. These would phase in
starting in 2009. The near-term program also contains more stringent
emissions standards for existing locomotives. These would apply when
the locomotive is remanufactured and would take effect as soon as
certified remanufacture systems are available (as early as 2008), but
no later than 2010 (2013 for Tier 2 locomotives). We are requesting
comment on an alternative under consideration that would apply a
similar requirement to existing marine diesel engines when they are
remanufactured. We are also proposing long-term emissions standards for
newly-built locomotives and marine diesel engines based on the
application of high-efficiency catalytic aftertreatment technology.
These standards would phase in beginning in 2015 for locomotives and
2014 for marine diesel engines. We estimate PM reductions of 90 percent
and NO_X reductions of 80 percent from engines meeting these
standards, compared to engines meeting the current standards.
We project that by 2030, this program would reduce annual emissions
of NO_X and PM by 765,000 and 28,000 tons, respectively.
These reductions are estimated to annually prevent 1,500 premature
deaths, 170,000 work days lost, and 1,000,000 minor restricted-activity
days. The estimated annual monetized health benefits of this rule in
2030 would be approximately $12 billion, assuming a 3 percent discount
rate (or $11 billion assuming a 7 percent discount rate). These
estimates would be increased substantially if we were to adopt the
remanufactured marine engine program concept. The annual cost of the
proposed program in 2030 would be significantly less, at approximately
$600 million.

DATES: Comments must be received on or before July 2, 2007. Under the
Paperwork Reduction Act, comments on the information collection
provisions must be received by OMB on or before May 3, 2007.

ADDRESSES: Submit your comments, identified by Docket ID No. EPA-HQ-
OAR-2003-0190, by one of the following methods:
? http://www.regulations.gov: Follow the on-line instructions for
submitting comments.
? Fax: (202) 566-1741
? Mail: Air Docket, Environmental Protection Agency,
Mailcode: 6102T, 1200 Pennsylvania Ave., NW., Washington, DC 20460. In
addition, please mail a copy of your comments on the information
collection provisions to the Office of Information and Regulatory
Affairs, Office of Management and Budget (OMB), Attn: Desk Officer for
EPA, 725 17th St., NW., Washington, DC 20503.
? Hand Delivery: EPA Docket Center, (EPA/DC) EPA West, Room
3334, 1301 Constitution Ave., NW, Washington DC, 20004. Such deliveries
are only accepted during the Docket's normal hours of operation, and
special arrangements should be made for deliveries of boxed information.
Instructions: Direct your comments to Docket ID No. EPA-HQ-OAR-
2003-0190. EPA's policy is that all comments received will be included
in the public docket without change and may be made available online at
http://www.regulations.gov, including any personal information
provided, unless the comment includes information claimed to be
Confidential Business Information (CBI) or other information whose
disclosure is restricted by statute. Do not submit information that you
consider to be CBI or otherwise protected through http://www.regulations.gov
or e-mail. The http://www.regulations.gov Web site
is an ``anonymous access'' system, which means EPA will not know your
identity or contact information unless you provide it in the body of
your comment. If you send an e-mail comment directly to EPA without
going through http://www.regulations.gov your e-mail address will be
automatically captured and included as part of the comment that is
placed in the public docket and made available on the Internet. If you
submit an electronic comment, EPA recommends that you include your name
and other contact information in the body of your comment and with any
disk or CD-ROM you submit. If EPA cannot read your comment due to
technical difficulties and cannot contact you for clarification, EPA
may not be able to consider your comment. Electronic files should avoid
the use of special characters, any form of encryption, and be free of
any defects or viruses. For additional information about EPA's public
docket visit the EPA Docket Center homepage at http://www.epa.gov/
epahome/dockets.htm. For additional instructions on submitting
comments, go to section I.A. of the SUPPLEMENTARY INFORMATION section
of this document, and also go to section VIII.A. of the Public
Participation section of this document.
Docket: All documents in the docket are listed in the
http://www.regulations.gov index. Although listed in the index, some
information is not publicly available, e.g., CBI or other information
whose disclosure is restricted by statute. Certain other material, such
as copyrighted material, will be publicly available only in hard copy.
Publicly available docket materials are available either electronically
in http://www.regulations.gov or in hard copy at the EPA-EQ-OAR-2003-
0190 Docket, EPA/DC, EPA West, Room 3334, 1301 Constitution Ave., NW.,
Washington,

[[Page 15939]]

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
EPA-EQ-OAR-2003-0190 is (202) 566-1742.
Hearing: Two hearings will be held, at 10 a.m. on Tuesday, May 8,
2007 in Seattle, WA, and at 10 a.m. on Thursday, May 10, 2007 in
Chicago, IL. For more information on these hearings or to request to
speak, see section VIII.C. ``WILL THERE BE A PUBLIC HEARING.''

FOR FURTHER INFORMATION CONTACT: John Mueller, U.S. EPA, Office of
Transportation and Air Quality, Assessment and Standards Division
(ASD), Environmental Protection Agency, 2000 Traverwood Drive, Ann
Arbor, MI 48105; telephone number: (734) 214-4275; fax number: (734)
214-4816; e-mail address: Mueller.John@epa.gov, or Assessment and
Standards Division Hotline; telephone number: (734) 214-4636.

SUPPLEMENTARY INFORMATION:

General Information

? Does This Action Apply to Me?

? Locomotive
Entities potentially regulated by this action are those which
manufacture, remanufacture and/or import locomotives and/or locomotive
engines; and those which own and operate locomotives. Regulated
categories and entities include:

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Examples of
Category NAICS Code \1\ potentially affected
entities
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Industry...................... 333618, 336510... Manufacturers,
remanufacturers and
importers of
locomotives and
locomotive engines.
Industry...................... 482110, 482111, Railroad owners and
482112. operators.
Industry...................... 488210........... Engine repair and
maintenance.
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\1\ North American Industry Classification System (NAICS).

This table is not intended to be exhaustive, but rather provides a
guide for readers regarding entities likely to be regulated by this
action. This table lists the types of entities that EPA is now aware
could potentially be regulated by this action. Other types of entities
not listed in the table could also be regulated. To determine whether
your company is regulated by this action, you should carefully examine
the applicability criteria in 40 CFR sections 92.1, 92.801, 92.901,
92.1001, 1065.1, 1068.1, 85.1601, 89.1, and the proposed regulations.
If you have questions, consult the person listed in the preceding FOR
FURTHER INFORMATION CONTACT section.
? Marine
This proposed action would affect companies and persons that
manufacture, sell, or import into the United States new marine
compression-ignition engines, companies and persons that rebuild or
maintain these engines, companies and persons that make vessels that
use such engines, and the owners/operators of such vessels. Affected
categories and entities include:

------------------------------------------------------------------------
Examples of
Category NAICS Code \1\ potentially affected
entities
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Industry...................... 333618........... Manufacturers of new
marine diesel
engines.
Industry...................... 33661 and 346611. Ship and boat
building; ship
building and
repairing.
Industry...................... 811310........... Engine repair,
remanufacture, and
maintenance.
Industry...................... 483.............. Water transportation,
freight and
passenger.
Industry...................... 336612........... Boat building
(watercraft not
built in shipyards
and typically of the
type suitable or
intended for
personal use).
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\1\ North American Industry Classification System (NAICS).

? Additional Information About This Rulemaking

? Locomotive
The current emission standards for locomotive engines were adopted
by EPA in 1998 (see 63 FR 18978, April 16, 1998). This notice of
proposed rulemaking relies in part on information that was obtained for
that rule, which can be found in Public Docket A-94-31. That docket is
incorporated by reference into the docket for this action, OAR-2003-0190.
? Marine
The current emission standards for new commercial marine diesel
engines were adopted in 1999 and 2003 (see 64 FR 73300, December 29,
1999 and 66 FR 9746, February 28, 2003). The current emission standards
for new recreational marine diesel engines were adopted in 2002 (see 67
FR 68241, November 8, 2002). The current emission standards for marine
diesel engines below 37 kW (50 hp) were adopted in 1998 (see 63 FR
56967, October 23, 1998). This notice of proposed rulemaking relies in
part on information that was obtained for those rules, which can be
found in Public Dockets A-96-40, A-97-50, A-98-01, A-2000-01, and A-
2001-11. Those dockets are incorporated by reference into the docket
for this action, OAR-2003-0190.
? Other Dockets
This notice of proposed rulemaking relies in part on information
that was obtained for our recent highway diesel and nonroad diesel
rulemakings, which can be found in Public Dockets A-99-06 and A-2001-28
(see also OAR 2003-

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0012).\1\ \2\ Those dockets are incorporated by reference
into the docket for this action, OAR-2003-0190.
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\1 2\ Control of Air Pollution From New Motor Vehicles: Heavy-
Duty Engine and Vehicle Standards and Highway Diesel Fuel Sulfur
Control Requirements, 66 FR 5002 (January 18, 2001); Control of
Emissions of Air Pollution From Nonroad Diesel Engines and Fuel, 69
FR 38958 (June 29, 2004).
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Outline of This Preamble

I. Overview
A. What Is EPA Proposing?
B. Why Is EPA Making This Proposal?
II. Air Quality and Health Impacts
A. Overview
B. Public Health Impacts
C. Other Environmental Effects
D. Other Criteria Pollutants Affected by This NPRM
E. Emissions From Locomotive and Marine Diesel Engines
III. Emission Standards
A. What Locomotives and Marine Engines Are Covered?
B. Existing EPA Standards
C. What Standards Are We Proposing?
D. Are the Proposed Standards Feasible?
E. What Are EPA's Plans for Diesel Marine Engines on Large
Ocean-Going Vessels?
IV. Certification and Compliance Program
A. Issues Common to Locomotives and Marine
B. Compliance Issues Specific to Locomotives
C. Compliance Issues Specific to Marine Engines
V. Costs and Economic Impacts
A. Engineering Costs
B. Cost Effectiveness
C. EIA
VI. Benefits
A. Overview
B. Quantified Human Health and Environmental Effects of the
Proposed Standards
C. Monetized Benefits
D. What Are the Significant Limitations of the Benefit-Cost Analysis?
E. Benefit-Cost Analysis
VII. Alternative Program Options
A. Summary of Alternatives
B. Summary of Results
VIII. Public Participation
A. How Do I Submit Comments?
B. How Should I Submit CBI to the Agency?
C. Will There Be a Public Hearing?
D. Comment Period
E. What Should I Consider as I Prepare My Comments for EPA?
IX. 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
X. Statutory Provisions and Legal Authority

I. Overview

This proposal is an important step in EPA's ongoing National Clean
Diesel Campaign (NCDC). In recent years, we have adopted major new
programs designed to reduce emissions from highway and nonroad diesel
engines.\3\ When fully implemented, these new programs would largely
eliminate emissions of harmful pollutants from these sources. This
Notice of Proposed Rulemaking (NPRM) sets out the next step in this
ambitious effort by addressing two additional diesel sectors that are
major sources of air pollution nationwide: locomotive engines and
marine diesel engines below 30 liters per cylinder displacement.\4\
This addresses all types of diesel locomotives-- line-haul, switch, and
passenger rail, and all types of marine diesel engines below 30 liters
per cylinder displacement (hereafter collectively called ``marine
diesel engines.''). These include marine propulsion engines used on
vessels from recreational and small fishing boats to super-yachts, tugs
and Great Lakes freighters, and marine auxiliary engines ranging from
small gensets to large generators on ocean-going vessels.\5\
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\3\ See 65 FR 6698 (February 10, 2000), 66 FR 5001 (January 18,
2001), and 69 FR 38958 (June 29, 2004) for the final rules regarding
the light-duty Tier 2, clean highway diesel (2007 highway diesel)
and clean nonroad diesel (nonroad Tier 4) programs, respectively.
EPA has also recently promulgated a clean stationary diesel engine
rule containing standards similar to those in the nonroad Tier 4
rule. See 71 FR 39153. See also http://www.epa.gov/diesel/ for
information on all EPA programs that are part of the NCDC.
\4\ In this NPRM, ``marine diesel engine'' refers to
compression-ignition marine engines below 30 liters per cylinder
displacement unless otherwise indicated. Engines at or above 30
liters per cylinder are being addressed in separate EPA actions,
including a planned rulemaking, participation on the U.S. delegation
to the International Maritime Organization's standard-setting work,
and EPA's new Clean Ports USA Initiative
(http://www.epa.gov/cleandiesel/ports/index.htm).
\5\ Marine diesel engines at or above 30 l/cyl displacement are
not included in this program. See Section III.E, below.
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Emission levels for locomotive and marine diesel engines remain at
high levels--comparable to the emissions standards for highway trucks
in the early 1990s--and emit high level of pollutants that contribute
to unhealthy air in many areas of the U.S. Nationally, in 2007 these
engines account for about 20 percent of mobile source NO_X
emissions and 25 percent of mobile source diesel PM_2.5
emissions. Absent new emissions standards, we expect overall emissions
from these engines to remain relatively flat over the next 10 to 15
years due to existing regulations such as lower fuel sulfur
requirements and the phase-in of locomotive and marine diesel Tier 1
and Tier 2 engine standards but starting in about 2025 emissions from
these engines would begin to grow. Under today's proposed program, by
2030, annual NO_X emissions from locomotive and marine diesel
engines would be reduced by 765,000 tons and PM_2.5 and
28,000 tons. Without new controls, by 2030, these engines would become
a large portion of the total mobile source emissions inventory
constituting 35 percent of mobile source NO_X emissions and
65 percent of diesel PM emissions.
We followed certain principles when developing the elements of this
proposal. First, the program must achieve sizeable reductions in PM and
NO_X emissions as early as possible. Second, as we did in the
2007 highway diesel and clean nonroad diesel programs, we are
considering engines and fuels together as a system to maximize
emissions reductions in a highly cost-effective manner. The groundwork
for this systems approach was laid in the 2004 nonroad diesel final
rule which mandated that locomotive and marine diesel fuel comply with
the 15 parts per million sulfur cap for ultra-low sulfur diesel fuel
(ULSD) by 2012, in anticipation of this rulemaking (69 FR 38958, June
29, 2004). The costs, benefits, and other impacts of the locomotive and
marine diesel fuel regulation are covered in the 2004 rulemaking and
are not duplicated here. Lastly, we are proposing standards and
implementation schedules that take full advantage of the efforts now
being expended to develop advanced emissions control technologies for
the highway and nonroad sectors. As discussed throughout this proposal,
the proposed standards represent a feasible progression in the
application of advanced technologies, providing a cost-effective
program with very large public health and welfare benefits.
The proposal consists of a three-part program. First, we are
proposing more stringent standards for existing locomotives that would
apply when they are remanufactured. The proposed remanufactured
locomotive program would take effect as soon as certified remanufacture
systems are available (as early as 2008), but no later than 2010 (2013
for Tier 2 locomotives). We are also requesting comment on an
alternative under consideration that would apply a similar requirement
to existing marine diesel engines when

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they are remanufactured. Second, we are proposing a set of near-term
emission standards, referred to as Tier 3, for newly-built locomotives
and marine engines, that reflect the application of technologies to
reduce engine-out PM and NO_X. Third, we are proposing
longer-term standards, referred to as Tier 4, that reflect the
application of high-efficiency catalytic aftertreatment technology
enabled by the availability of ULSD. These standards phase in over
time, beginning in 2014. We are also proposing provisions to eliminate
emissions from unnecessary locomotive idling.
Locomotives and marine diesel engines designed to these proposed
standards would achieve PM reductions of 90 percent and NO_X
reductions of 80 percent, compared to engines meeting the current Tier
2 standards. The proposed standards would also yield sizeable
reductions in emissions of nonmethane hydrocarbons (NMHC), carbon
monoxide (CO), and hazardous compounds known as air toxics. Table I-1
summarizes the PM and NO_X emission reductions for the
proposed standards compared to today's (Tier 2) emission standards or,
in the case of remanufactured locomotives, compared to the current
standards for each tier of locomotives covered.

Table I.-1.--Reductions From Levels of Existing Standards
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Sector Proposed standards tier PM NOX
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Locomotives..................................... Remanufactured Tier 0.................. 60% 15-20%
Remanufactured Tier 1.................. 50
Remanufactured Tier 2.................. 50
Tier 3................................. 50
Tier 4................................. 90 80
Marine Diesel Engines \a\....................... Remanufactured Engines \b\............. 25-60 up to 20
Tier 3................................. 50 20
Tier 4................................. 90 80
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\a\ Existing and proposed standards vary by displacement and within power categories. Reductions indicated are
typical.
\b\ This proposal asks for comment on an alternative under consideration that would reduce emissions from
existing marine diesel engines. See section VII.A(2).

Combined, these reductions would result in substantial benefits to
public health and welfare and to the environment. We project that by
2030 this program would reduce annual emissions of NO_X and
PM by 765,000 and 28,000 tons, respectively, and the magnitude of these
reductions would continue to grow well beyond 2030. We estimate that
these annual emission reductions would prevent 1,500 premature
mortalities in 2030. These annual emission reductions are also
estimated to prevent 1,000,000 minor restricted-activity days, 170,000
work days lost, and other quantifiable benefits. All told, the
estimated monetized health benefits of this rule in 2030 would be
approximately $12 billion, assuming a 3 percent discount rate (or $11
billion assuming a 7 percent discount rate). The annual cost of the
program in 2030 would be significantly less, at approximately $600 million.

A. What Is EPA Proposing?

This proposal is a further step in EPA's ongoing program to control
emissions from diesel engines, including those used in marine vessels
and locomotives. EPA's current standards for newly-built and
remanufactured locomotives were adopted in 1998 and were implemented in
three tiers (Tiers 0, 1, and 2) over 2000 through 2005. The current
program includes Tier 0 emission limits for existing locomotives
originally manufactured in 1973 or later, that apply when they are
remanufactured. The standards for marine diesel engines were adopted in
1998 for engines under 37 kilowatts (kW), in 1999 for commercial marine
engines, and in 2002 for recreational marine engines. These various
Tier 1 and Tier 2 standards phase in from 1999 through 2009, depending
on engine size and application. The most stringent of these existing
locomotive and marine diesel engine standards are similar in stringency
to EPA's nonroad Tier 2 standards that are now in the process of being
replaced by Tier 3 and 4 standards.
The major elements of the proposal are summarized below. We are
also proposing revised testing, certification, and compliance
provisions to better ensure emissions control in use. Detailed
provisions and our justifications for them are discussed in sections
III and IV and in the draft Regulatory Impact Analysis (RIA). Section
VII of this preamble describes a number of alternatives that we
considered in developing this proposal, including a more simplistic
approach that would introduce aftertreatment-based standards earlier.
Our analysis shows that such an approach would result in higher
emissions and fewer health and welfare benefits than we project will be
realized from the program we are proposing today. After evaluating the
alternatives, we believe that our proposed program provides the best
opportunity for achieving timely and very substantial emissions
reductions from locomotive and marine diesel engines. It best takes
into account the need for appropriate lead time to develop and apply
the technologies necessary to meet these emission standards, the goal
of achieving very significant emissions reductions as early as
possible, the interaction of requirements in this proposal with
existing highway and nonroad diesel engine programs, and other legal
and policy considerations.
Overall, this comprehensive three-part approach to setting
standards for locomotives and marine diesel engines would provide very
large reductions in PM, NO_X, and toxic compounds, both in
the near-term (as early as 2008), and in the long-term. These
reductions would be achieved in a manner that: (1) Is very cost-
effective, (2) leverages technology developments in other diesel
sectors, (3) aligns well with the clean diesel fuel requirements
already being implemented, and (4) provides the lead time needed to
deal with the significant engineering design workload that is involved.
We are asking for comments on all aspects of the proposal, including
standards levels and implementation dates, and on the alternatives
discussed in this proposal.
(1) Locomotive Emission Standards
We are proposing stringent exhaust emissions standards for newly-
built and remanufactured locomotives, furthering the initiative for
cleaner locomotives started in 2004 with the establishment of the ULSD
locomotive fuel program, and adding this important category of engines
to the highway and nonroad

[[Page 15942]]

diesel applications already covered under EPA's National Clean Diesel
Campaign.\6\
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\6\ We are not proposing any change to the current definition of
a ``new locomotive'' in 40 CFR Sec. 92.2. The terms ``new
locomotive'', ``new locomotive engine'', ``freshly manufactured
locomotive'', ``freshly manufactured locomotive engine'',
``repower'', ``remanufacture'', ``remanufactured locomotive'', and
``remanufactured locomotive engine'' all have formal definitions in
40 CFR 92.2. In this notice, the term ``newly-built locomotive'' is
synonymous with ``freshly manufactured locomotive''.
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In the Advance Notice of Proposed Rulemaking (ANPRM) for this
proposal (69 FR 39276, June 29, 2004), we suggested a program for
comment that would bring about the introduction of high-efficiency
exhaust aftertreatment to this sector in a single step. Although it has
taken longer than expected to develop, the proposal we are issuing
today is far more comprehensive than we envisioned in 2004. Informed by
extensive analyses documented in the draft RIA and numerous discussions
with stakeholders since then, this proposal goes significantly beyond
that vision. It sets out standards for locomotives in three steps to
more fully leverage the opportunities provided by both the already-
established clean fuel programs, and the migration of clean diesel
technology from the highway and nonroad sectors. It also addresses the
large and long-lived existing locomotive fleet with stringent new
emissions requirements at remanufacture starting in 2008. Finally, it
sets new requirements for idle emissions control on newly-built and
remanufactured locomotives.
Briefly, for newly-built line-haul locomotives we are proposing a
new Tier 3 PM standard of 0.10 grams per brake horsepower-hour (g/bhp-
hr), based on improvements to existing engine designs. This standard
would take effect in 2012. We are also proposing new Tier 4 standards
of 0.03 g/bhp-hr for PM and 1.3 g/bhp-hr for NO_X, based on
the evolution of high-efficiency catalytic aftertreatment technologies
now being developed and introduced in the highway diesel sector. The
Tier 4 standards would take effect in 2015 and 2017 for PM and
NO_X, respectively. We are proposing that remanufactured Tier
2 locomotives meet a PM standard of 0.10 g/bhp-hr, based on the same
engine design improvements as Tier 3 locomotives, and that
remanufactured Tier 0 and Tier 1 locomotives meet a 0.22 g/bhp-hr PM
standard. We also propose that remanufactured Tier 0 locomotives meet a
NO_X standard of 7.4 g/bhp-hr, the same level as current Tier
1 locomotives, or 8.0 g/bhp-hr if the locomotive is not equipped with a
separate loop intake air cooling system. Section III provides a
detailed discussion of these proposed new standards, and section IV
details improvements being proposed to the applicable test,
certification, and compliance programs.
In setting our original locomotive emission standards in 1998, the
historic pattern of transitioning older line-haul locomotives to road-
and yard-switcher service resulted in our making little distinction
between line-haul and switch locomotives. Because of the increase in
the size of new locomotives in recent years, that pattern cannot be
sustained by the railroad industry, as today's 4000+ hp (3000+ kW)
locomotives are poorly suited for switcher duty. Furthermore, although
there is still a fairly sizeable legacy fleet of older smaller line-
haul locomotives that could find their way into the switcher fleet,
essentially the only newly-built switchers put into service over the
last two decades have been of radically different design, employing one
to three smaller high-speed diesel engines designed for use in nonroad
applications. In light of these trends, we are establishing new
standards and special certification provisions for newly-built and
remanufactured switch locomotives that take these trends into account.
Locomotives spend a substantial amount of time idling, during which
they emit harmful pollutants and consume fuel. Two ways that idling
time can be reduced are through the use of automated systems to stop
idling locomotive engines (restarting them on an as-needed basis), and
through the use of small low-emitting auxiliary engines to provide
essential accessory power. Both types of systems are installed in a
number of U.S. locomotives today for various reasons, including to save
fuel, to help meet current Tier 0 emissions standards, and to address
complaints from railyard neighbors about noise and pollution from
idling locomotives.
We are proposing that idle control systems be required on all
newly-built Tier 3 and Tier 4 locomotives. We also propose that they be
installed on all existing locomotives that are subject to the proposed
remanufactured engine standards, at the point of first remanufacture
under the proposed standards, unless already equipped with idle
controls. We are proposing that automated stop/start systems be
required, but encourage the use of auxiliary power units by allowing
their emission reduction to be factored into the certification test
program as appropriate.
Taken together, the proposed elements described above constitute a
comprehensive program that would address the problems caused by
locomotive emissions from both a near-term and long-term perspective,
and do so more completely than would have occurred under the concept
described in the ANPRM. It would do this while providing for an orderly
and cost-effective implementation schedule for the railroads, builders,
and remanufacturers.
(2) Marine Engine Emission Standards
We are also proposing emissions standards for newly-built marine
diesel engines with displacements under 30 liters per cylinder
(referred to as Category 1 and 2, or C1 and C2, engines). This would
include engines used in commercial, recreational, and auxiliary power
applications, and those below 37 kW (50 hp) that were previously
regulated separately in our nonroad diesel program. As with
locomotives, our ANPRM described a one-step marine diesel program that
would bring about the introduction of high-efficiency exhaust
aftertreatment in this sector. Just as for locomotives, our subsequent
extensive analyses (documented in the draft RIA) and numerous
discussions with stakeholders since then have resulted in this proposal
for standards in multiple steps, with the longer-term implementation of
advanced technologies focused especially on the engines with the
greatest potential for large PM and NO_X emission reductions.
The proposed marine diesel engine standards include stringent
engine-based Tier 3 standards for newly-built marine diesel engines
that phase in beginning in 2009. These are followed by aftertreatment-
based Tier 4 standards for engines above 600 kW (800 hp) that phase in
beginning in 2014. The specific levels and implementation dates for the
proposed Tier 3 and Tier 4 standards vary by engine sub-groupings.
Although this results in a somewhat complicated array of emissions
standards, it will ensure the most stringent standards feasible for
each group of newly-built marine engines, and will help engine and
vessel manufacturers to implement the program in a cost effective
manner that also emphasizes early emission reductions. The proposed
standards and implementation schedules, as well as their technological
feasibility, are described in detail in section III of this preamble.
We are also requesting comment on an alternative we are considering
to address the considerable impact of emissions from large marine diesel

[[Page 15943]]

engines installed in vessels currently in the fleet. We have in the
past considered but not finalized a program to regulate such engines as
``new'' engines at the time of remanufacture, similar to the approach
taken in the locomotive program. We are again considering such a
program in the context of this rulemaking and are soliciting comments
on this alternative.
Briefly summarized, it would consist of two parts. In the first
part, which could begin as early as 2008, vessel owners and rebuilders
would be required to install a certified emissions control system when
the engine is remanufactured, if such a system were available.
Initially, we would expect the systems installed on remanufactured
marine engines to be those certified for the remanufactured locomotive
program, although this alternative would not limit the program to only
those engines. Eventually manufacturers would be expected to provide
systems for other large engines as well. In the second part, to take
effect in 2013, marine diesel engines identified by EPA as high-sales
volume engine models would have to meet specified emissions standards
when remanufactured. The rebuilder or owner would be required to either
use a system certified to meet the standards or, if no certified
systems were available, to either retrofit an emission reduction
technology for the engine that demonstrates at least a 25 percent
reduction or to repower (replace the engine with a new one). The
alternative under consideration is described in more detail in section
VII.A(2). We request comment on the elements of this alternative as
well as other possible approaches to achieve this goal, with the view
that EPA may adopt a remanufacture program in the final rule if appropriate.

B. Why Is EPA Making This Proposal?

(1) Locomotives and Marine Diesels Contribute to Serious Air Pollution
Problems
Locomotive and marine diesel engines subject to today's proposal
generate significant emissions of fine particulate matter
(PM_2.5) and nitrogen oxides (NO_X) that contribute
to nonattainment of the National Ambient Air Quality Standards for
PM_2.5 and ozone. NO_X is a key precursor to ozone
and secondary PM formation. These engines also emit hazardous air
pollutants or air toxics, which are associated with serious adverse
health effects. Emissions from locomotive and marine diesel engines
also cause harm to public welfare, including contributing to visibility
impairment and other harmful environmental impacts across the US.
The health and environmental effects associated with these
emissions are a classic example of a negative externality (an activity
that imposes uncompensated costs on others). With a negative
externality, an activity's social cost (the cost borne to society
imposed as a result of the activity taking place) exceeds its private
cost (the cost to those directly engaged in the activity). In this
case, as described below and in Section II, emissions from locomotives
and marine diesel engines and vessels impose public health and
environmental costs on society. However, these added costs to society
are not reflected in the costs of those using these engines and
equipment. The market system itself cannot correct this externality
because firms in the market are rewarded for minimizing their
production costs, including the costs of pollution control. In
addition, firms that may take steps to use equipment that reduces air
pollution may find themselves at a competitive disadvantage compared to
firms that do not. To correct this market failure and reduce the
negative externality from these emissions, it is necessary to give
producers the signals for the social costs generated from the
emissions. The standards EPA is proposing will accomplish this by
mandating that locomotives and marine diesel engines reduce their
emissions to a technologically feasible limit. In other words, with
this proposed rule the costs of the transportation services produced by
these engines and equipment will account for social costs more fully.
Emissions from locomotive and marine diesel engines account for
substantial portions of the country's ambient PM_2.5 and
NO_X levels. We estimate that today hese engines account for
about 20 percent of mobile source NO_X emissions and about 25
percent of mobile source diesel PM _2.5 emissions. Under
today's proposed standards, by 2030, annual NO_X emissions
from these diesel engines would be reduced by 765,000 tons and
PM_2.5 emissions by 28,000 tons, and those reductions would
continue to grow beyond 2030 as fleet turnover to the clean engines is
completed.
EPA has already taken steps to bring emissions levels from light-
duty and heavy-duty highway, and nonroad diesel vehicles and engines to
very low levels over the next decade, as well as certain stationary
diesel engines also subject to these standards, while the emission
levels for locomotive and marine diesel engines remain at much higher
levels--comparable to the emissions for highway trucks in the early 1990s.
Both ozone and PM_2.5 contribute to serious public health
problems, including premature mortality, aggravation of respiratory and
cardiovascular disease (as indicated by increased hospital admissions
and emergency room visits, school absences, lost work days, and
restricted activity days), changes in lung function and increased
respiratory symptoms, altered respiratory defense mechanisms, and
chronic bronchitis. Diesel exhaust is of special public health concern,
and since 2002 EPA has classified it as likely to be carcinogenic to
humans by inhalation at environmental exposures.\7\ Recent studies are
showing that populations living near large diesel emission sources such
as major roadways,\8\ rail yards, and marine ports \9\ are likely to
experience greater diesel exhaust exposure levels than the overall U.S.
population, putting them at greater health risks. We are currently
studying the size of the U.S. population living near a sample of
approximately 60 marine ports and rail yards, and will place the
information in the docket upon completion prior to the final rule.
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\7\ U.S. EPA (2002) Health Assessment Document for Diesel Engine
Exhaust. EPA/600/8-90/057F. Office of Research and Development,
Washington DC. This document is available electronically at
http://cfpub.epa.gov/ncea/cfm/recordisplay.cfm?deid=29060.
\8\ Kinnee, E.J.; Touman, J.S.; Mason, R.; Thurman, J.; Beidler,
A.; Bailey, C.; Cook, R. (2004) Allocation of onroad mobile
emissions to road segments for air toxics modeling in an urban area.
Transport. Res. Part D 9: 139-150.
\9\ State of California Air Resources Board. Roseville Rail Yard
Study. Stationary Source Division, October 14, 2004. This document
is available electronically at: http://www.arb.ca.gov/diesel/documents/
rrstudy.htm and State of California Air Resources Board.
Diesel Particulate Matter Exposure Assessment Study for the Ports of
Los Angeles and Long Beach, April 2006. This document is available
electronically at: http://www.arb.ca.gov/regact/marine2005/portstudy0406.pdf.

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Today millions of Americans continue to live in areas that do not
meet existing air quality standards. Currently, ozone concentrations
exceeding the 8-hour ozone NAAQS occur over wide geographic areas,
including most of the nation's major population centers. As of October
2006 there are approximately 157 million people living in 116 areas
(461 full or partial counties) designated as not in attainment with the
8-hour ozone NAAQS. These numbers do not include people living in areas
where there is a potential that the area may fail to maintain or
achieve the 8-hour ozone NAAQS. With regard to PM_2.5
nonattainment, EPA has recently finalized nonattainment designations

[[Page 15944]]

(70 FR 943, Jan 5, 2005), and as of October 2006 there are 88 million
people living in 39 areas (which include all or part of 208 counties)
that either do not meet the PM_2.5 NAAQS or contribute to
violations in other counties. These numbers do not include individuals
living in areas that may fail to maintain or achieve the
PM_2.5 NAAQS in the future.
In addition to public health impacts, there are public welfare and
environmental impacts associated with ozone and PM_2.5
emissions which are also serious. Specifically, ozone causes damage to
vegetation which leads to crop and forestry economic losses, as well as
harm to national parks, wilderness areas, and other natural systems.
NO_X and direct emissions of PM_2.5 can contribute
to the substantial impairment of visibility in many part of the U.S.,
where people live, work, and recreate, including national parks,
wilderness areas, and mandatory class I federal areas. The deposition
of airborne particles can also reduce the aesthetic appeal of buildings
and culturally important articles through soiling, and can contribute
directly (or in conjunction with other pollutants) to structural damage
by means of corrosion or erosion. Finally, NO_X emissions
from diesel engines contribute to the acidification, nitrification, and
eutrophication of water bodies.
While EPA has already adopted many emission control programs that
are expected to reduce ambient ozone and PM_2.5 levels,
including the Clean Air Interstate Rule (CAIR) (70 FR 25162, May 12,
2005) and the Clean Air Nonroad Diesel Rule (69 FR 38957, June 29,
2004), the Heavy Duty Engine and Vehicle Standards and Highway Diesel
Fuel Sulfur Control Requirements (66 FR 5002, Jan. 18, 2001), and the
Tier 2 Vehicle and Gasoline Sulfur Program (65 FR 6698, Feb. 10, 2000),
the additional PM_2.5 and NO_X emission reductions
resulting from the standards proposed in this action would assist
states in attaining and maintaining the Ozone and the PM_2.5
NAAQS near term and in the decades to come.
In September 2006, EPA finalized revised PM_2.5 NAAQS
standards and over the next few years the Agency will undergo the
process of designating areas that are not able to meet this new
standard. EPA modeling, conducted as part of finalizing the revised
NAAQS, projects that in 2015 up to 52 counties with 53 million people
may violate either the daily, annual, or both standards for
PM_2.5 while an additional 27 million people in 54 counties
may live in areas that have air quality measurements within 10 percent
of the revised NAAQS. Even in 2020 up to 48 counties, with 54 million
people, may still not be able to meet the revised PM_2.5
NAAQS and an additional 25 million people, living in 50 counties, are
projected to have air quality measurements within 10 percent of the
revised standards. The locomotive and marine diesel PM_2.5
reductions resulting from this proposal will be needed by states to
both attain and maintain the revised PM_2.5 NAAQS.
State and local governments are working to protect the health of
their citizens and comply with requirements of the Clean Air Act (CAA
or ``the Act''). As part of this effort they recognize the need to
secure additional major reductions in both diesel PM_2.5 and
NO_X emissions by undertaking numerous state level
actions,\10\ while also seeking Agency action, including the setting of
stringent new locomotive and marine diesel engine standards being
proposed today.\11\ The emission reductions in this proposal will play
a critical part in state efforts to attain and maintain the NAAQS
through the next two decades.
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\10\ Two examples of state and local actions are: California Air
Resources Board (2006). Emission Reduction Plan for Ports and Goods
Movements, (April 2006). Available electronically at http://www.arb.ca.gov/
gmp/docs/finalgmpplan090905.pdf; Connecticut Department of
Environmental Protection. (2006). Connecticut's Clean Diesel Plan,
(January 2006). See http://www.dep.state.ct.us/air2/diesel/index.htm
for description of initiative.
\11\ For example, see letter dated September 23, 2006 from
Northeast States for Coordinated Air Use Management to Administrator
Stephen L. Johnson; September 7, 2006 letter from Executive Officer
of the California Air Resources Board to Acting Assistant
Administrator William L. Wehrum; August 9, 2006 letter from State
and Territorial Air Pollution Program Administrators and Association
of Local Air Pollution Control Officials (and other organizations)
to Administrator Stephen L. Johnson; January 20, 2006 letter from
Executive Director, Puget Sound Clean Air Agency to Administrator
Stephen L. Johnson; June 30, 2005 letter from Western Regional Air
Partnership to Administrator Stephen L. Johnson.
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While the program we are proposing today will help many states and
communities achieve cleaner air, for some areas, the reductions will
not be large enough or early enough to assist them in meeting near term
ozone and PM air quality goals. More can be done, beyond what we are
proposing today, to address the emissions from locomotive and marine
diesel engines. For example, as part of this proposal we are requesting
comment on a concept to set emission standards for existing large
marine diesel engines when they are remanufactured. Were we to finalize
such a concept, it could provide substantial emission reductions,
beginning in the next few years, from some of the large legacy fleets
of dirtier diesel engines.
At the time of our previous locomotive rulemaking, the State of
California worked with the railroads operating in southern California
to develop and implement a corollary program, ensuring that the
cleanest technologies are expeditiously introduced in these areas with
greatest air quality improvement needs. Today's proposal includes
provisions, such as streamlined switcher locomotive certification using
clean nonroad engines, that are well-suited to encouraging early deployment
of cleaner technologies through the development of similar programs.
In addition to regulatory programs, the Agency has a number of
voluntary programs that partner government, industry, and local
communities together to help address challenging air quality problems.
The EPA SmartWay program has initiatives to reduce unnecessary
locomotive idling and to encourage the use of idle reduction
technologies that can substantially reduce locomotive emissions while
reducing fuel consumption. EPA's National Clean Diesel Campaign,
through its Clean Ports USA program, is working with port authorities,
terminal operators, and trucking and rail companies to promote cleaner
diesel technologies and strategies today through education, incentives,
and financial assistance for diesel emissions reductions at ports. Part
of these efforts involves voluntary retrofit programs that can further
reduce emissions from the existing fleet of diesel engines. Finally,
many of the companies operating in states and communities suffering
from poor air quality have voluntarily entered into Memoranda of
Understanding (MOUs) designed to ensure that the cleanest technologies
are used first in regions with the most challenging air quality issues.
Together, these approaches can augment the regulations being
proposed today helping states and communities achieve larger reductions
sooner in the areas of our country that need them the most. The Agency
remains committed to furthering these programs and others so that all
of our citizens can breathe clean healthy air.
(2) Advanced Technology Solutions
Air pollution from locomotive and marine diesel exhaust is a
challenging problem. However, we believe it can be addressed
effectively through the use of existing technology to reduce engine-out
emissions combined with high-efficiency catalytic aftertreatment
technologies. As discussed in greater detail in section III.D, the
development of these aftertreatment technologies for

[[Page 15945]]

highway and nonroad diesel applications has advanced rapidly in recent
years, so that very large emission reductions in PM and NO_X
(in excess of 90 and 80 percent, respectively) can be achieved.
High-efficiency PM control technologies are being broadly used in
many parts of the world, and in particular to comply with EPA's heavy-
duty truck standards now taking effect with the 2007 model year. These
technologies are highly durable and robust in use, and have also proved
extremely effective in reducing exhaust hydrocarbon (HC) emissions.
However, as discussed in detail in section III.D, these emission
control technologies are very sensitive to sulfur in the fuel. For the
technology to be viable and capable of controlling an engine's
emissions over the long term, we believe it will require diesel fuel
with sulfur content capped at the 15 ppm level.
Control of NO_X emissions from locomotive and marine
diesel engines can also be achieved with high-efficiency exhaust
emission control technologies. Such technologies are expected to be
used to meet the stringent NO_X standards included in EPA's
heavy-duty highway diesel and nonroad Tier 4 programs, and have been in
production for heavy duty trucks in Europe since 2005, as well as in
many stationary source applications throughout the world. These
technologies are also sensitive to sulfur.
Section III.D discusses additional engineering challenges in
applying these technologies to newly-built locomotive and marine
engines, as well as the development steps that we expect to be taken to
resolve the challenges. With the lead time available and the assurance
of ULSD for the locomotive and marine sectors in 2012, as provided by
our 2004 final rule for nonroad engines and fuel, we are confident the
proposed application of advanced technology to locomotives and marine
diesels will proceed at a reasonable rate of progress and will result
in systems capable of achieving the proposed standards on the proposed
schedule.
(3) Basis for Action Under the Clean Air Act
Authority for the actions promulgated in this documents is granted
to the Environmental Protections Agency (EPA) by sections 114, 203,
205, 206, 207, 208, 213, 216, and 301(a) of the Clean Air Act as
amended in 1990 (CAA or ``the Act'') (42 U.S.C. 7414, 7522, 7524, 7525,
7541, 7542, 7547, 7550 and 7601(a)).
EPA is promulgating emissions standards for new marine diesel
engines pursuant to its authority under section 213(a)(3) and (4) of
the Clean Air Act (CAA). EPA is promulgating emission standards for new
locomotives and new engines used in locomotives pursuant to its
authority under section 213(a)(5) of the CAA.
CAA section 213(a)(3) directs the Administrator to set
NO_X, VOCs, or carbon monoxide, standards for classes or
categories of engines that contribute to ozone or carbon monoxide
concentrations in more than one nonattainment area, like marine diesel
engines. These ``standards shall achieve the greatest degree of
emission reduction achievable through the application of technology
which the Administrator determines will be available for the engines or
vehicles, giving appropriate consideration to cost, lead time, noise,
energy, and safety factors associated with the application of such
technology.''
CAA section 213(a)(4), authorizes the Administrator to establish
standards to control emissions of pollutants which ``may reasonably be
anticipated to endanger public health and welfare,'' where the
Administrator determines, as it has done for emissions of PM, that
nonroad engines as a whole contribute significantly to such air
pollution. The Administrator may promulgate regulations that are deemed
appropriate, taking into account costs, noise, safety, and energy
factors, for classes or categories of new nonroad vehicles and engines
which cause or contribute to such air pollution, like diesel marine engines.
Finally, section 213(a)(5) directs EPA to adopt emission standards
for new locomotives and new engines used in locomotives that achieve
the ``greatest degree of emissions reductions achievable through the
use of technology that the Administrator determines will be available
for such vehicles and engines, taking into account the cost of applying
such technology within the available time period, the noise, energy,
and safety factors associated with the applications of such
technology.'' Section 213(a)(5) does not require any review of the
contribution of locomotive emissions to pollution, though EPA does
provide such information in this proposal. As described in section III
of this Preamble and in Chapter 4 of the draft RIA, EPA has evaluated
the available information to determine the technology the will be available
for locomotives and engines proposed to be subject to EPA standards.
EPA is also acting under its authority to implement and enforce
both the marine diesel emission standards and the locomotive emissions
standards. Section 213(d) provides that the standards EPA adopts for
both new locomotive and marine diesel engines ``shall be subject to
sections 206, 207, 208, and 209'' of the Clean Air Act, with such
modifications that the Administrator deems appropriate to the
regulations implementing these sections. In addition, the locomotive
and marine standards ``shall be enforced in the same manner as [motor
vehicle] standards prescribed under section 202'' of the Act. Section
213(d) also grants EPA authority to promulgate or revise regulations as
necessary to determine compliance with, and enforce, standards adopted
under section 213.
As required under section 213(a)(3), (4), and (5) we believe the
evidence provided in section III.D of this Preamble and in Chapter 4 of
draft RIA indicates that the stringent emission standards proposed
today for newly-built and remanufactured locomotive engines and newly-
built marine diesel engines are feasible and reflect the greatest
degree of emission reduction achievable through the use of technology
that will be available in the model years to which they apply. We also
believe this may be the case for the alternative identified for
existing marine engines in section VII.A(2) of this preamble. We have
given appropriate consideration to costs in proposing these standards.
Our review of the costs and cost-effectiveness of these standards
indicate that they will be reasonable and comparable to the cost-
effectiveness of other emission reduction strategies that have been
required. We have also reviewed and given appropriate consideration to
the energy factors of this rule in terms of fuel efficiency as well as
any safety and noise factors associated with these proposed standards.
The information in section II of this Preamble and Chapter 2 of the
draft RIA regarding air quality and public health impacts provides
strong evidence that emissions from marine diesel engines and
locomotives significantly and adversely impact public health or
welfare. EPA has already found in previous rules that emissions from
new marine diesel engines contribute to ozone and carbon monoxide (CO)
concentrations in more than one area which has failed to attain the
ozone and carbon monoxide NAAQS (64 FR 73300, December 29, 1999). EPA
has also previously determined that it is appropriate to establish
standards for PM from marine diesel engines under section 213(a)(4),
and the additional information on diesel exhaust carcinogenicity noted
above reinforces

[[Page 15946]]

this finding. In addition, we have already found that emissions from
nonroad engines as a whole significantly contribute to air pollution
that may reasonably be anticipated to endanger public welfare due to
regional haze and visibility impairment (67 FR 68241, Nov. 8, 2002). We
propose to find here, based on the information in section II of this
preamble and Chapters 2 and 3 of the draft RIA that emissions from the
new marine diesel engines likewise contribute to regional haze and to
visibility impairment.
The PM and NO_X emission reductions resulting from the
standards proposed in this action would be important to states' efforts
in attaining and maintaining the Ozone and the PM_2.5 NAAQS
in the near term and in the decades to come. As noted above, the risk
to human health and welfare would be significantly reduced by the
standards proposed today.

II. Air Quality and Health Impacts

The locomotive and marine diesel engines subject to today's
proposal generate significant emissions of particulate matter (PM) and
nitrogen oxides (NO_X) that contribute to nonattainment of
the National Ambient Air Quality Standards (NAAQS) for PM_2.5
and ozone. These engines also emit hazardous air pollutants or air
toxics which are associated with serious adverse health effects.
Finally, emissions from locomotive and marine diesel engines cause harm
to the public welfare, contribute to visibility impairment, and
contribute to other harmful environmental impacts across the U.S.
By 2030, the proposed standards are expected to reduce annual
locomotive and marine diesel engine PM_2.5 emissions by
28,000 tons; NO_X emissions by 765,000 tons; and volatile
organic compound (VOC) emissions by 42,000 tons as well as reductions
in carbon monoxide (CO) and toxic compounds known as air toxics.\12\
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\12\ Nationwide locomotive and marine diesel engines comprise
approximately 3 percent of the nonroad mobile sources hydrocarbon
inventory. EPA National Air Quality and Emissions Trends Report
1999. March 2001, Document Number: EPA 454/R-0-004. This document is
available electronically at: http://www.epa.gov/air/airtrends/aqtrnd99/.

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We estimate that reductions of PM_2.5, NO_X,
and VOC emissions from locomotive and marine diesel engines would
produce nationwide air quality improvements. According to air quality
modeling performed in conjunction with this proposed rule, if
finalized, all 39 current PM_2.5 nonattainment areas would
experience a decrease in their 2020 and 2030 design values. Likewise
all 116 mandatory class I federal areas would see improvements in their
visibility. This rule would also result in substantial nationwide ozone
benefits. The air quality modeling conducted for ozone estimates that
in 2020 and 2030, 114 of the current 116 ozone nonattainment areas would
see improvements in ozone air quality as a result of this proposed rule.

A. Overview

From a public health perspective, we are concerned with locomotive
and marine diesel engines' contributions to atmospheric levels of
particulate matter in general, diesel PM_2.5 in particular,
and various gaseous air toxics, and ozone. Today, locomotive and marine
diesel engine emissions represent a substantial portion of the U.S.
mobile source diesel PM_2.5 and NO_X emissions
accounting for approximately 20 percent of mobile source NO_X
and 25 percent of mobile source diesel PM_2.5. These
proportions are even higher in some urban areas. Over time, the
relative contribution of these diesel engines to air quality problems
is expected to increase as the emission contribution from other mobile
sources decreases and the usage of locomotives and marine vessels
increases. By 2030, without further emissions controls beyond those
already adopted for these engines, locomotive and marine diesel engines
nationally will emit more than 65 percent of the total mobile source
diesel PM_2.5 emissions and 35 percent of the total mobile
source NO_X emissions.
Based on the most recent data available for this rule, air quality
problems continue to persist over a wide geographic area of the United
States. As of October 2006 there are approximately 88 million people
living in 39 designated areas (which include all or part of 208
counties) that either do not meet the current PM_2.5 NAAQS or
contribute to violations in other counties, and 157 million people
living in 116 areas (which include all or part of 461 counties)
designated as not in attainment for the 8-hour ozone NAAQS. These
numbers do not include the people living in areas where there is a
significant future risk of failing to maintain or achieve either the
PM_2.5 or ozone NAAQS. Figure II-1 illustrates the widespread
nature of these problems. This figure depicts counties which are
currently designated nonattainment for either or both the 8-hour ozone
NAAQS and PM_2.5 NAAQS. It also shows the location of
mandatory class I federal areas for visibility.
BILLING CODE 6560-50-P

[[Page 15947]]
[GRAPHIC]
[TIFF OMITTED] TP03AP07.000

BILLING CODE 6560-50-C
The engine standards proposed in this rule would help reduce
emissions of PM, NO_X, VOCs, CO, and air toxics and their
associated health and

[[Page 15948]]

environmental effects. Emissions from locomotives and diesel marine
engines contribute to PM and ozone concentrations in many, if not all,
of these nonattainment areas.\13\ The engine standards being proposed
today would become effective as early as 2008 making the expected
PM_2.5, NO_X, and VOC inventory reductions from
this rulemaking critical to states as they seek to either attain or
maintain the current PM_2.5 or ozone NAAQS.
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\13\ See section II.B.(1)(d) and II.B.(2)(d) for a summary of
the impact emission reductions from locomotive and marine diesel
engines will have on air quality in current PM_2.5 and
ozone nonattainment areas.
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Beyond the impact locomotive and marine diesel engines have on our
nation's ambient air quality the diesel exhaust emissions emanating
from these engines are also of particular concern since diesel exhaust
is classified as a likely human carcinogen.\14\ Many people spend a
large portion of time in or near areas of concentrated locomotive or
marine diesel emissions, near rail yards, marine ports, railways, and
waterways. Recent studies show that populations living near large
diesel emission sources such as major roadways,\15\ rail yards \16\ and
marine ports \17\ are likely to experience greater diesel exhaust
exposure levels than the overall U.S. population, putting them at a
greater health risk. We are currently studying the size of the U.S.
population living near a sample of approximately 60 marine ports and
rail yards, and will place that information in the docket upon
completion prior to the final rule. The diesel PM_2.5
reductions which occur as a result of this proposed rule would benefit
the population near these sources and also assist state and local
governments as they work to meet the NAAQS.
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\14\ U.S. EPA (2002) Health Assessment Document for Diesel
Engine Exhaust. EPA/600/8-90/057F. Office of Research and
Development, Washington, DC. This document is available
electronically at http://cfpub.epa.gov/ncea/cfm/recordisplay.cfm?deid=29060.
\15\ Kinnee, E.J.; Touma, J.S.: Mason, R.; Thurman, J.; Beidler,
A.; Bailey, C.; Cook, R. (2004) Allocation of onroad mobile
emissions to road segments for air toxics modeling in an urban area.
Transport. Res. Part D 9:139-150; also see Cohen, J.; Cook, R;
Bailey, C.R.; Carr, E. (2005) Relationship between motor vehicle
emissions of hazardous pollutants, roadway proximity, and ambient
concentrations in Portland, Oregon. Environ. Modeling & Software 20: 7-12.
\16\ Hand, R.; Di, P; Servin, A.; Hunsaker, L.; Suer, C. (2004)
Roseville Rail Yard Study. California Air Resources Board. [Online
at http://www.arb.ca.gov/diesel/documents/rrstudy.htm]
\17\ Di P.; Servin, A.; Rosenkranz, K.; Schwehr, B.; Tran, H.
(April 2006); Diesel Particulate Matter Exposure Assessment Study
for the Ports of Los Angeles and Long Beach. State of California Air
Resources Board. This document is available electronically at:
http://www.arb.ca.gov/regact/marine2005/portstudy0406.pdf.

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In the following three sections we review important public health
effects linked to pollutants emitted from locomotive and marine diesel
engines first describing the human health effects and the current and
expected future ambient levels of direct or indirectly caused
pollution. Following the discussion of health effects, we will discuss
the modeled air quality benefits which are estimated to result from
regulating these engines. We also discuss a number of other welfare
effects associated with emissions from diesel engines. These effects
include visibility impairment, ecological and property damage caused by
acid deposition, eutrophication and nitrification of surface waters,
environmental threats posed by polycyclic organic matter (POM)
deposition, and plant and crop damage from ozone.
Finally, in section E we describe the locomotive and marine engine
emission inventories for the primary pollutants affected by the
proposal. We present current and projected future levels of emissions
for the base case, including anticipated reductions from control
programs already adopted by EPA and the States, but without the
controls proposed today. Then we identify expected emission reductions
from nonroad locomotive and marine diesel engines. These reductions
would make important contributions to controlling the health and
welfare problems associated with ambient PM and ozone levels and with
diesel-related air toxics.
Taken together, the materials in this section describe the need for
tightening emission standards from both locomotive and marine diesel
engines and the air quality and public health benefits we expect as a
result of this proposed rule. This section is not an exhaustive
treatment of these issues. For a fuller understanding of the topics
treated here, you should refer to the extended presentations in Chapter
2 of the Draft Regulatory Impact Analysis (RIA) accompanying this proposal.

B. Public Health Impacts

(1) Particulate Matter
The proposed locomotive and marine engine standards would result in
significant reductions of primary PM_2.5 emissions from these
sources. In addition, locomotive and marine diesel engines emit high
levels of NO_X which react in the atmosphere to form
secondary PM_2.5, ammonium nitrate. Locomotive and marine
diesel engines also emit SO₂ and HC which react in the
atmosphere to form secondary PM_2.5 composed of sulfates and
organic carbonaceous PM_2.5. This proposed rule would reduce
both the directly emitted diesel PM and secondary PM emissions.
(a) Background
Particulate matter (PM) represents a broad class of chemically and
physically diverse substances. It can be principally characterized as
discrete particles that exist in the condensed (liquid or solid) phase
spanning several orders of magnitude in size. PM is further described
by breaking it down into size fractions. PM₁₀ refers to
particles generally less than or equal to 10 micrometers ([mu]m).
PM_2.5 refers to fine particles, those particles generally
less than or equal to 2.5 [mu]m in diameter. Inhalable (or
``thoracic'') coarse particles refer to those particles generally
greater than 2.5 [mu]m but less than or equal to 10 [mu]m in diameter.
Ultrafine PM refers to particles less than 100 nanometers (0.1 [mu]m).
Larger particles tend to be removed by the respiratory clearance
mechanisms (e.g. coughing), whereas smaller particles are deposited
deeper in the lungs.
Fine particles are produced primarily by combustion processes and
by transformations of gaseous emissions (e.g., SO_X,
NO_X and VOCs) in the atmosphere. The chemical and physical
properties of PM_2.5 may vary greatly with time, region,
meteorology, and source category. Thus, PM_2.5, may include a
complex mixture of different pollutants including sulfates, nitrates,
organic compounds, elemental carbon and metal compounds. These
particles can remain in the atmosphere for days to weeks and travel
through the atmosphere hundreds to thousands of kilometers.
The primary PM_2.5 NAAQS includes a short-term (24-hour)
and a long-term (annual) standard. The 1997 PM_2.5 NAAQS
established by EPA set the 24-hour standard at a level of 65 [mu]g/
m3 based on the 98th percentile concentration averaged over
three years. (This air quality statistic compared to the standard is
referred to as the ``design value.'') The annual standard specifies an
expected annual arithmetic mean not to exceed 15 [mu]g/m3
averaged over three years. EPA has recently finalized PM_2.5
nonattainment designations for the 1997 standard (70 FR 943, Jan 5,
2005).\18\ All areas currently in nonattainment for

[[Page 15949]]

PM_2.5 will be required to meet these 1997 standards between
2009 and 2014.
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\18\ US EPA, Air Quality Designations and Classifications for
the Fine Particles (PM_2.5) National Ambient Air Quality
Standards, December 17, 2004. (70 FR 943, Jan 5. 2005) This document
is also available on the web at: http://www.epa.gov/pmdesignations/.

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As can be seen in Figure II-1 ambient PM_2.5 levels
exceeding the 1997 PM_2.5 NAAQS are widespread throughout the
country. As of October 2006 there were approximately 88 million people
living in 39 areas (which include all or part of 208 counties) that
either do not meet the 1997 PM_2.5 NAAQS or contribute to
violations in other counties. These numbers do not include the people
living in areas where there is a significant future risk of failing to
maintain or achieve the PM_2.5 NAAQS.
EPA has recently amended the NAAQS for PM_2.5 (71 FR
61144, October 17, 2006). The final rule, signed on September 21, 2006
and published in the Federal Register on October 17, 2006, addressed
revisions to the primary and secondary NAAQS for PM to provide
increased protection of public health and welfare, respectively. The
level of the 24-hour PM_2.5 NAAQS was revised from 65 [mu]g/
m\3\ to 35 [mu]g/m\3\ to provide increased protection against health
effects associated with short-term exposures to fine particles. The
current form of the 24-hour PM_2.5 standard was retained
(e.g., based on the 98th percentile concentration averaged over three
years). The level of the annual PM_2.5 NAAQS was retained at
15 [mu]g/m\3\, continuing protection against health effects associated
with long-term exposures. The current form of the annual
PM_2.5 standard was retained as an annual arithmetic mean
averaged over three years, however, the following two aspects of the
spatial averaging criteria were narrowed: (1) The annual mean
concentration at each site shall be within 10 percent of the spatially
averaged annual mean, and (2) the daily values for each monitoring site
pair shall yield a correlation coefficient of at least 0.9 for each
calendar quarter.
With regard to the secondary PM_2.5 standards, EPA has
revised these standards to be identical in all respects to the revised
primary standards. Specifically, EPA has revised the current 24-hour
PM_2.5 secondary standard by making it identical to the
revised 24-hour PM_2.5 primary standard and retained the
annual PM_2.5 secondary standard. This suite of secondary
PM_2.5 standards is intended to provide protection against
PM-related public welfare effects, including visibility impairment,
effects on vegetation and ecosystems, and material damage and soiling.
The 2006 standards became effective on December 18, 2006. As a
result of the 2006 PM_2.5 standard, EPA will designate new
nonattainment areas in early 2010. The timeframe for areas attaining
the 2006 PM NAAQS will likely extend from 2015 to 2020.
Table II-1 presents the number of counties in areas currently
designated as nonattainment for the 1997 PM_2.5 NAAQS as well
as the number of additional counties which have monitored data that is
violating the 2006 PM_2.5 NAAQS. In total more than 106
million U.S. residents, in 257 counties are living in areas which
either violate either the 1997 PM_2.5 standard or the 2006
PM_2.5 standard.

Table II-1.--Fine Particle Standards: Current Nonattainment Areas and
Other Violating Counties
------------------------------------------------------------------------
Number of
counties Population \a\
------------------------------------------------------------------------
1997 PM2.5 Standards: 39 areas currently 208 88,394,000
designated.............................
2006 PM2.5 Standards: Counties with 49 18,198,676
violating monitors \b\.................
-------------------------------
Total............................... 257 106,595,676
------------------------------------------------------------------------
\a\ Population numbers are from 2000 census data.
\b\ This table provides an estimate of the counties violating the 2006
PM2.5 NAAQS based on 2003-05 air quality data. The areas designated as
nonattainment for the 2006 PM2.5 NAAQS will be based on 3 years of air
quality data from later years. Also, the county numbers in the summary
table includes only the counties with monitors violating the 2006
PM2.5 NAAQS. The monitored county violations may be an underestimate
of the number of counties and populations that will eventually be
included in areas with multiple counties designated nonattainment.

EPA has already adopted many emission control programs that are
expected to reduce ambient PM_2.5 levels and as a result of
these programs, the number of areas that fail to achieve the 1997
PM_2.5 NAAQS is expected to decrease. Even so, EPA modeling
projects that in 2015, with all current controls, up to 52 counties
with 53 million population may not attain some combination of the
current annual standard of 15 [mu]g/m\3\ and the revised daily standard
of 35 [mu]g/m\3\, and that even in 2020 up to 48 counties with 54
million population will still not be able to attain either the annual,
daily, or both the annual and daily PM_2.5 standards.\19\
This does not account for additional areas that have air quality
measurements within 10 percent of the 2006 PM_2.5 standard.
These areas, although not violating the standards, would also benefit
from the additional reductions from this rule ensuring long term
maintenance of the PM NAAQS.
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\19\ Final RIA PM NAAQS, Chapter 2: Defining the
PM_2.5 Air Quality Problem. October 17, 2006.
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States have told EPA that they need the reductions this proposed
rule would provide in order to meet and maintain both the current 1997
PM_2.5 NAAQS and the 2006 PM_2.5 NAAQS. Based on
the final rule designating and classifying PM_2.5
nonattainment areas, most PM_2.5 nonattainment areas will be
required to attain the 1997 PM_2.5 NAAQS in the 2009 to 2015
time frame, and then be required to maintain the NAAQS thereafter. The
emissions standards for engine remanufacturing being proposed in this
action would become effective as early as 2008, but no later than 2010,
and states would rely on these expected PM_2.5 reductions to
help them to either attain or maintain the 1997 PM_2.5 NAAQS.
In the long term, the emission reductions resulting from the proposed
locomotive and marine diesel engine standards would be important to
states efforts to attain and maintain the 2006 PM_2.5 NAAQS.
(b) Health Effects of PM_2.5
Scientific studies show ambient PM is associated with a series of
adverse health effects. These health effects are discussed in detail in
the 2004 EPA Particulate Matter Air Quality Criteria Document (PM AQCD)
for PM, and the 2005 PM Staff Paper.\20\ \21\ \22\ Further discussion
of health effects associated

[[Page 15950]]

with PM can also be found in the draft RIA for this proposal.
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\20\ U.S. EPA (1996) Air Quality Criteria for Particulate
Matter, EPA 600-P-95-001aF, EPA 600-P-95-001bF. This document is
available in Docket EPA-HQ-OAR.
\21\ U.S. EPA (2004) Air Quality Criteria for Particulate Matter
(Oct 2004), Volume I Document No. EPA600/P-99/002aF and Volume II
Document No. EPA600/P-99/002bF. This document is available in Docket
EPA-HQ-OAR.
\22\ U.S. EPA (2005) Review of the National Ambient Air Quality
Standard for Particulate Matter: Policy Assessment of Scientific and
Technical Information, OAQPS Staff Paper. EPA-452/R-05-005. This
document is available in Docket EPA-HQ-OAR.
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Health effects associated with short-term exposures (hours to days)
to ambient PM include premature mortality, increased hospital
admissions, heart and lung diseases, increased cough, adverse lower-
respiratory symptoms, decrements in lung function and changes in heart
rate rhythm and other cardiac effects. Studies examining populations
exposed to different levels of air pollution over a number of years,
including the Harvard Six Cities Study and the American Cancer Society
Study, show associations between long-term exposure to ambient
PM_2.5 and both total and cardio respiratory mortality.\23\
In addition, a reanalysis of the American Cancer Society Study shows an
association between fine particle and sulfate concentrations and lung
cancer mortality.\24\ The locomotive and marine diesel engines, covered
in this proposal contribute to both acute and chronic PM_2.5
exposures. Additional information on acute exposures is available in
Chapter 2 of the draft RIA for this proposal.
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\23\ Dockery, DW; Pope, CA III: Xu, X; et al. 1993. An
association between air pollution and mortality in six U.S. cities.
N Engl J Med 329:1753-1759.
\24\ Pope Ca, III; Thun, MJ; Namboodiri, MM; Docery, DW; Evans,
JS; Speizer, FE; Heath, CW. 1995. Particulate air pollution as a
predictor of mortality in a prospective study of U.S. adults. Am J
Respir Crit Care Med 151:669-674.
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These health effects of PM_2.5 have been further
documented in local impact studies which have focused on health effects
due to PM_2.5 exposures measured on or near roadways.\25\
Taking account of all air pollution sources, including both spark-
ignition (gasoline) and diesel powered vehicles, these latter studies
indicate that exposure to PM_2.5 emissions near roadways,
dominated by mobile sources, are associated with potentially serious
health effects. For instance, a recent study found associations between
concentrations of cardiac risk factors in the blood of healthy young
police officers and PM_2.5 concentrations measured in
vehicles.\26\ Also, a number of studies have shown associations between
residential or school outdoor concentrations of some constituents of
fine particles found in motor vehicle exhaust and adverse respiratory
outcomes, including asthma prevalence in children who live near major
roadways.\27\ \28\ \29\ Although the engines considered in this
proposal differ with those in these studies with respect to their
applications and fuel qualities, these studies provide an indication of
the types of health effects that might be expected to be associated
with personal exposure to PM_2.5 emissions from large marine
diesel and locomotive engines. The proposed controls would help to
reduce exposure, and specifically exposure near marine ports and rail
yard related PM_2.5 sources.
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\25\ Riekider, M.; Cascio, W.E.; Griggs, T.R..; Herbst, M.C.;
Bromberg, P.A.; Neas, L.; Williams, R.W.; Devlin, R.B. (2003)
Particulate Matter Exposures in Cars is Associated with
Cardiovascular Effects in Healthy Young Men. Am. J. Respir. Crit.
Care Med. 169: 934-940.
\26\ Riediker, M.; Cascio, W.E.; Griggs, T.R.; et al. (2004)
Particulate matter exposure in cars is associated with
cardiovascular effects in healthy young men. Am. J. Respir. Crit.
Care Med. 169: 934-940.
\27\ Van Vliet, P.; Knape, M.; de Hartog, J.; Janssen, N.;
Harssema, H.; Brunekreef, B. (1997). Motor vehicle exhaust and
chronic respiratory symptoms in children living near freeways. Env.
Research 74: 122-132.
\28\ Brunekreef, B., Janssen, N.A.H.; de Hartog, J.; Harssema,
H.; Knape, M.; van Vliet, P. (1997). Air pollution from truck
traffic and lung function in children living near roadways.
Epidemiology 8:298-303.
\29\ Kim, J.J.; Smorodinsky, S.; Lipsett, M.; Singer, B.C.;
Hodgson, A.T.; Ostro, B. (2004). Traffic-related air pollution near
busy roads: The East Bay children's respiratory health study. Am. J.
Respir. Crit. Care Med. 170: 520-526.
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Recently, new studies \30\ from the State of California provide
evidence that PM_2.5 emissions within marine ports and rail
yards contribute significantly to elevated ambient concentrations near
these sources. A substantial number of people experience exposure to
locomotive and marine diesel engine emissions, raising potential health
concerns. Additional information on marine port and rail yard emissions
and ambient exposures can be found in section.B.3 of this preamble.
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\30\ State of California Air Resources Board. Roseville Rail
Yard Study. Stationary Source Division, October 14, 2004. This
document is available electronically at: http://www.arb.ca.gov/
diesel/documents/rrstudy.htm and State of California Air Resources
Board and State of California Air Resources Board. Diesel
Particulate Matter Exposure Assessment Study for the Ports of Los
Angeles and Long Beach, April 2006. This document is available
electronically at: ftp://ftp.arb.ca.gov/carbis/msprog/offroad/marinevess/
documents/portstudy0406.pdf.

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(c) PM_2.5 Air Quality Modeling Results
Air quality modeling performed for this proposal shows that in 2020
and 2030 all 39 current PM_2.5 nonattainment areas would
experience decreases in their PM_2.5 design values. For areas
with PM_2.5 design values greater than 15 [mu]g/m3
the modeled future-year PM_2.5 design values are expected to
decrease on average by 0.06 [mu]g/m3 in 2020 and 0.14 [mu]g/
m3 in 2030. The maximum decrease for future-year
PM_2.5 design values in 2020 would be 0.35 [mu]g/
m3 and 0.90 [mu]g/m3 in 2030. The reductions are
discussed in more detail in Chapter 2 of the draft RIA.
The geographic impact of the proposed locomotive and marine diesel
engine controls in 2030 on PM_2.5 design values (DV) in
counties across the US, can be seen in Figure II-2.
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[GRAPHIC]
[TIFF OMITTED] TP03AP07.001
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Figure II-2 illustrates that the greatest emission reductions in
2030 are projected to occur in Southern California where 3 counties
would experience reductions in their PM_2.5 design values of
-0.50 to -0.90 [mu]g/m3. The next level of emission
reductions would occur among 13 counties geographically dispersed in
the southeastern U.S., southern Illinois, and southern California. An
additional 325 counties spread across the U.S. would see a decrease in
their PM_2.5 DV ranging from -0.05 to -0.24 [mu]g/m3.
(d) PM Air Quality Modeling Methodology
A national scale air quality modeling analysis was performed to
estimate future year annual and daily PM_2.5 concentrations
and visibility for this proposed rule. To model the air quality
benefits of this rule we used the Community-Scale Air Quality (CMAQ)
model. CMAQ simulates the numerous physical and chemical processes
involved in the formation, transport, and destruction of ozone and
particulate matter. In addition to the CMAQ model, the modeling
platform includes the emissions, meteorology, and initial and boundary
condition data which are inputs to this model. Consideration of the
different processes that affect primary directly emitted and secondary
PM at the regional scale in different locations is fundamental to
understanding and assessing the effects of pollution control measures
that affect PM, ozone and deposition of pollutants to the surface. A
complete description of the CAMQ model and methodology employed to
develop the future year impacts of this proposed rule are found in
Chapter 2.1 of the draft RIA.
It should be noted that the emission control scenarios used in the
air quality and benefits modeling are slightly different than the
emission control program being proposed. The differences reflect
further refinements of the regulatory program since we performed the
air quality modeling for this rule. Emissions and air quality modeling
decisions are made early in the analytical process. Chapter 3 of the
draft RIA describes the changes in the inputs and resulting emission
inventories between the preliminary assumptions used for the air
quality modeling and the final proposed regulatory scenario. These
refinements to the proposed program would not significantly change the
results summarized here or our conclusions drawn from this analysis.

(2) Ozone

The proposed locomotive and marine engine standards are expected to
result in significant reductions of NO_X and VOC emissions.
NO_X and VOC contribute to the formation of ground-level
ozone pollution or smog. People in many areas across the U.S. continue
to be exposed to unhealthy levels of ambient ozone.
(a) Background
Ground-level ozone pollution is formed by the reaction of volatile
organic compounds (VOCs) and nitrogen oxides (NO_X) in the
atmosphere in the presence of heat and sunlight. These two pollutants,
often referred to as ozone precursors, are emitted by many types of
pollution sources, such as highway and nonroad motor vehicles and
engines, power plants, chemical plants, refineries, makers of consumer
and commercial products, industrial facilities, and smaller ``area'' sources.
The science of ozone formation, transport, and accumulation is
complex.\31\ Ground-level ozone is produced and destroyed in a cyclical
set of chemical reactions, many of which are sensitive to temperature
and sunlight. When ambient temperatures and sunlight levels remain high
for several days and the air is relatively stagnant, ozone and its
precursors can build up and result in more ozone than typically would
occur on a single high-temperature day. Ozone also can be transported
from pollution sources into areas hundreds of miles upwind, resulting
in elevated ozone levels even in areas with low local VOC or
NO_X emissions.
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\31\ U.S. EPA Air Quality Criteria for Ozone and Related
Photochemical Oxidants (Final). U.S. Environmental Protection
Agency, Washington, D.C., EPA 600/R- 05/004aF-cF, 2006. This
document may be accessed electronically at:
http://www.epa.gov/ttn/naaqs/standards/ozone/s_o3_cr_cd.html.
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The highest levels of ozone are produced when both VOC and
NO_X emissions are present in significant quantities on clear
summer days. Relatively small amounts of NO_X enable ozone to
form rapidly when VOC levels are relatively high, but ozone production
is quickly limited by removal of the NO_X. Under these
conditions NO_X reductions are highly effective in reducing
ozone while VOC reductions have little effect. Such conditions are
called ``NO_X-limited.'' Because the contribution of VOC
emissions from biogenic (natural) sources to local ambient ozone
concentrations can be significant, even some areas where man-made VOC
emissions are relatively low can be NO_X-limited.
When NO_X levels are relatively high and VOC levels
relatively low, NO_X forms inorganic nitrates (i.e.,
particles) but relatively little ozone. Such conditions are called
``VOC-limited.'' Under these conditions, VOC reductions are effective
in reducing ozone, but NO_X reductions can actually increase
local ozone under certain circumstances. Even in VOC-limited urban
areas, NO_X reductions are not expected to increase ozone
levels if the NO_X reductions are sufficiently large.
Rural areas are usually NO_X-limited, due to the
relatively large amounts of biogenic VOC emissions in many rural areas.
Urban areas can be either VOC- or NO_X-limited, or a mixture
of both, in which ozone levels exhibit moderate sensitivity to changes
in either pollutant.
Ozone concentrations in an area also can be lowered by the reaction
of nitric oxide with ozone, forming nitrogen dioxide (NO₂);
as the air moves downwind and the cycle continues, the NO₂
forms additional ozone. The importance of this reaction depends, in
part, on the relative concentrations of NO_X, VOC, and ozone,
all of which change with time and location.
The current ozone National Ambient Air Quality Standards (NAAQS)
has an 8-hour averaging time.\32\ The 8-hour ozone NAAQS, established
by EPA in 1997, is based on well-documented science demonstrating that
more people were experiencing adverse health effects at lower levels of
exertion, over longer periods, and at lower ozone concentrations than
addressed by the previous one-hour ozone NAAQS. The current ozone NAAQS
addresses ozone exposures of concern for the general population and
populations most at risk, including children active outdoors, outdoor
workers, and individuals with pre-existing respiratory disease, such as
asthma. The 8-hour ozone NAAQS is met at an ambient air quality
monitoring site when the average of the annual fourth-highest daily
maximum 8-hour average ozone concentration over three years is less
than or equal to 0.084 ppm.
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\32\ EPA's review of the ozone NAAQS is underway and a proposal
is scheduled for May 2007 with a final rule scheduled for February 2008.
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Ozone concentrations exceeding the level of the 8-hour ozone NAAQS
occur over wide geographic areas, including most of the nation's major
population centers.\33\ As of October 2006 there are approximately 157
million people living in 116 areas (which include all or part

[[Page 15953]]

of 461 counties) designated as not in attainment with the 8-hour ozone
NAAQS. These numbers do not include the people living in areas where
there is a future risk of failing to maintain or achieve the 8-hour
ozone NAAQS.
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\33\ A listing of the 8-hour ozone nonattainment areas is
included in the draft RIA for this proposed rule.
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EPA has already adopted many emission control programs that are
expected to reduce ambient ozone levels. These control programs are
described in section I.B.(1) of this preamble. As a result of these
programs, the number of areas that fail to meet the 8-hour ozone NAAQS
in the future is expected to decrease.
Based on recent ozone modeling performed for the CAIR analysis,\34\
which does not include any additional local ozone precursor controls,
we estimate that in 2010, 24 million people are projected to live in 37
Eastern counties exceeding the 8-hour ozone NAAQS. An additional 61
million people are projected to live in 148 Eastern counties expected
to be within 10 percent of violating the 8-hour ozone NAAQS in 2010.
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\34\ Technical Support Document for the Final Clean Air
Interstate Rule Air Quality Modeling. This document is available in
Docket EPA-HQ-OAR-2003-0190.
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States with 8-hour ozone nonattainment areas will be required to
take action to bring those areas into compliance in the future. Based
on the final rule designating and classifying 8-hour ozone
nonattainment areas (69 FR 23951, April 30, 2004), most 8-hour ozone
nonattainment areas will be required to attain the 8-hour ozone NAAQS
in the 2007 to 2013 time frame and then be required to maintain the 8-
hour ozone NAAQS thereafter.\35\ We expect many of the 8-hour ozone
nonattainment areas will need to adopt additional emission reduction
programs. The expected NO_X and VOC reductions from the
standards proposed in this action would be important to states as they
seek to either attain or maintain the 8-hour ozone NAAQS.
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\35\ The Los Angeles South Coast Air Basin 8-hour ozone
nonattainment area will have to attain before June 15, 2021.
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(b) Health Effects of Ozone
The health and welfare effects of ozone are well documented and are
assessed in EPA's 2006 ozone Air Quality Criteria Document (ozone AQCD)
and EPA staff papers. 36 37 38 Ozone can irritate the
respiratory system, causing coughing, throat irritation, and/or
uncomfortable sensation in the chest. Ozone can reduce lung function
and make it more difficult to breathe deeply, and breathing may become
more rapid and shallow than normal, thereby limiting a person's
activity. Ozone can also aggravate asthma, leading to more asthma
attacks that require a doctor's attention and/or the use of additional
medication. Animal toxicological evidence indicates that with repeated
exposure, ozone can inflame and damage the lining of the lungs, which
may lead to permanent changes in lung tissue and irreversible
reductions in lung function. People who are more susceptible to effects
associated with exposure to ozone include children, the elderly, and
individuals with respiratory disease such as asthma. There is also
suggestive evidence that certain people may have greater genetic
susceptibility. People can also have heightened vulnerability to ozone
due to greater exposures (e.g., children and outdoor workers).
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\36\ U.S. EPA Air Quality Criteria for Ozone and Related
Photochemical Oxidants (Final). U.S. Environmental Protection
Agency, Washington, D.C., EPA 600/R-05/004aF-cF, 2006. This document
may be accessed electronically at:
http://www.epa.gov/ttn/naaqs/standards/ozone/s_o3_cr_cd.html.
\37\ U.S. EPA (1996) Review of National Ambient Air Quality
Standards for Ozone, Assessment of Scientific and Technical
Information. OAQPS Staff Paper First Draft. EPA-452/R-96-007. This
document is available electronically at:
http://www.epa.gov/ttn/naaqs/standards/ozone/s_o3_cr_sp.html.
\38\ U.S. EPA (2006) Review of the National Ambient Air Quality
Standards for Ozone, Policy Assessment of Scientific and Technical
Information. OAQPS Staff Paper Second Draft. EPA-452/D-05-002. This
document is available electronically at:
http://www.epa.gov/ttn/naaqs/standards/ozone/s_o3_cr_sp.html.

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The recent ozone AQCD also examined relevant new scientific
information which has emerged in the past decade, including the impact
of ozone exposure on such health effect indicators as changes in lung
structure and biochemistry, inflammation of the lungs, exacerbation and
causation of asthma, respiratory illness-related school absence,
hospital admissions and premature mortality. In addition to supporting
and building further on conclusions from the 1996 AQCD, the 2006 AQCD
included new information on the health effects of ozone. Animal
toxicological studies have suggested potential interactions between
ozone and PM with increased responses observed to mixtures of the two
pollutants compared to either ozone or PM alone. The respiratory
morbidity observed in animal studies along with the evidence from
epidemiologic studies supports a causal relationship between acute
ambient ozone exposures and increased respiratory-related emergency
room visits and hospitalizations in the warm season. In addition, there
is suggestive evidence of a contribution of ozone to cardiovascular-
related morbidity and non-accidental and cardiopulmonary mortality.
EPA typically quantifies ozone-related health impacts in its
regulatory impact analyses (RIAs) when possible. In the analysis of
past air quality regulations, ozone-related benefits have included
morbidity endpoints and welfare effects such as damage to commercial
crops. EPA has not recently included a separate and additive mortality
effect for ozone, independent of the effect associated with fine
particulate matter. For a number of reasons, including (1) advice from
the Science Advisory Board (SAB) Health and Ecological Effects
Subcommittee (HEES) that EPA consider the plausibility and viability of
including an estimate of premature mortality associated with short-term
ozone exposure in its benefits analyses and (2) conclusions regarding
the scientific support for such relationships in EPA's 2006 Air Quality
Criteria for Ozone and Related Photochemical Oxidants (the CD), EPA is
in the process of determining how to appropriately characterize ozone-
related mortality benefits within the context of benefits analyses for
air quality regulations. As part of this process, we are seeking advice
from the National Academy of Sciences (NAS) regarding how the ozone-
mortality literature should be used to quantify the reduction in
premature mortality due to diminished exposure to ozone, the amount of
life expectancy to be added and the monetary value of this increased
life expectancy in the context of health benefits analyses associated
with regulatory assessments. In addition, the Agency has sought advice
on characterizing and communicating the uncertainty associated with
each of these aspects in health benefit analyses.
Since the NAS effort is not expected to conclude until 2008, the
agency is currently deliberating how best to characterize ozone-related
mortality benefits in its rulemaking analyses in the interim. For the
analysis of the proposed locomotive and marine standards, we do not
quantify an ozone mortality benefit. So that we do not provide an
incomplete picture of all of the benefits associated with reductions in
emissions of ozone precursors, we have chosen not to include an
estimate of total ozone benefits in the proposed RIA. By omitting ozone
benefits in this proposal, we acknowledge that this analysis
underestimates the benefits associated with the proposed standards. For
more information regarding the quantified benefits included in this
analysis, please refer to Chapter 6 of this RIA.

[[Page 15954]]

(c) Air Quality Modeling Results for Ozone
This proposed rule would result in substantial nationwide ozone
benefits. The air quality modeling conducted for ozone as part of this
proposed rulemaking projects that in 2020 and 2030, 114 of the current
116 ozone nonattainment areas would see improvements in ozone air
quality as a result of this proposed rule.
Results from the air quality modeling conducted for this rulemaking
indicates that the average and population-weighted average
concentrations over all U.S. counties would experience broad
improvement in ozone air quality. The decrease in average ozone
concentration in current nonattainment counties shows that the proposed
rule would help bring these counties into attainment. The decrease in
average ozone concentration for counties below the standard, but within
ten percent, shows that the proposed rule would also help those
counties to maintain the standard. All of these metrics show a decrease
in 2020 and a larger decrease in 2030, indicating in four different
ways the overall improvement in ozone air quality. For example, in
nonattainment counties, on a population-weighted basis, the 8-hour
ozone design value would decrease by 0.29 ppb in 2020 and 0.87 ppb in 2030.
The impact of the proposed reductions has also been analyzed with
respect to those areas that have the highest design values at or above
85 ppb in 2030. We project there would be 27 U.S. counties with design
values at or above 85 ppb in 2030. After implementation of this
proposed action, we project that 3 of these 27 counties would drop
below 85 ppb. Further, 17 of the 27 counties would be at least 10
percent closer to a design value of less than 85 ppb, and on average
all 27 counties would be about 30 percent closer to a design value of
less than 85 ppb.
BILLING CODE 6560-50-P

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[GRAPHIC]
[TIFF OMITTED] TP03AP07.002
BILLING CODE 6560-50-C
Figure II-3 shows those U.S. counties in 2030 which are projected
to experience a change in their ozone design values as a result of this

[[Page 15956]]

proposed rule. The most significant decreases, equal or greater than -
2.0 ppb, would occur in 7 counties across the U.S. including: Grant (-
2.1 ppb) and Lafayette (-2.0 ppb) Counties in Louisiana; Montgomery (-
2.0 ppb), Galveston (-2.0 ppb), and Jefferson (-2.0 ppb) Counties in
Texas; Warren County (-2.9 ppb) in Mississippi; and Santa Barbara
County (-2.7 ppb) in California. One hundred eighty-seven (187)
counties would see annual ozone design value reductions from -1.0 to -
1.9 ppb while an estimated 217 additional counties would see annual
design value reductions from -0.5 to -0.9 ppb. Note that 5 counties
including: Suffolk (+1.5 ppb) and Hampton (+0.8 ppb) Counties in
Virginia; Cook County (+0.7 ppb) in Illinois; Lake County (+0.2 ppb) in
Indiana; and San Bernardino County (+0.1 ppb) in California are
projected to experience an increase in ozone design values because of
the NO_X disbenefit that occurs under certain conditions.\39\
It is expected that future local and national controls that decrease
VOC, CO, and regional ozone will mitigate any localized disbenefits.
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\39\ NO_X reductions can at certain times and in some
areas cause ozone levels to increase. Such ``disbenefits'' are
predicted in our modeling for this proposed rule. For a discussion
of the phenomenon see the draft RIA Chapter 2.2. In spite of this
disbenefit, the air quality modeling we conducted makes clear that
the overall effect of this proposed rule is positive with 456 counties
experiencing a decrease in both their 2020 and 2030 ozone design value.
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EPA's review of the ozone NAAQS is currently underway and a
proposed decision in this review is scheduled for May 2007 with a final
rule scheduled for February 2008. If the ozone NAAQS is revised then
new nonattainment areas could be designated. While EPA is not relying
on it for purposes of justifying this proposal, the emission reductions
from this rulemaking would also be helpful to states if there is an
ozone NAAQS revision.
(d) Ozone Air Quality Modeling Methodology
A national scale air quality modeling analysis was performed to
estimate future year ozone concentrations for this proposed rule. To
model the air quality benefits of this rule we used the Community-Scale
Air Quality (CMAQ) model. CMAQ simulates the numerous physical and
chemical processes involved in the formation, transport, and
destruction of ozone and particulate matter. In addition to the CMAQ
model, the modeling platform includes the emissions, meteorology, and
initial and boundary condition data which are inputs to this model.
Consideration of the different processes that affect primary directly
emitted and secondary PM at the regional scale in different locations
is fundamental to understanding and assessing the effects of pollution
control measures that affect PM, ozone and deposition of pollutants to
the surface. A complete description of the CAMQ model and methodology
employed to develop the future year impacts of this proposed rule are
found in Chapter 2.1 of the draft RIA.
It should be noted that the emission control scenarios used in the
air quality and benefits modeling are slightly different than the
emission control program being proposed. The differences reflect
further refinements of the regulatory program since we performed the
air quality modeling for this rule. Emissions and air quality modeling
decisions are made early in the analytical process. Chapter 3 of the
draft RIA describes the changes in the inputs and resulting emission
inventories between the preliminary assumptions used for the air
quality modeling and the final proposed regulatory scenario. These
refinements to the proposed program would not significantly change the
results summarized here or our conclusions drawn from this analysis.
(3) Air Toxics
People experience elevated risk of cancer and other noncancer
health effects from exposure to air toxics. Mobile sources are
responsible for a significant portion of this risk. According to the
National Air Toxic Assessment (NATA) for 1999, mobile sources were
responsible for 44 percent of outdoor toxic emissions and almost 50
percent of the cancer risk. Benzene is the largest contributor to
cancer risk of all 133 pollutants quantitatively assessed in the 1999
NATA. Mobile sources were responsible for 68 percent of benzene
emissions in 1999. Although the 1999 NATA did not quantify cancer risks
associated with exposure to this diesel exhaust, EPA has concluded that
diesel exhaust ranks with the other air toxic substances that the
national-scale assessment suggests pose the greatest relative risk.
According to 1999 NATA, nearly the entire U.S. population was
exposed to an average level of air toxics that has the potential for
adverse respiratory health effects (noncancer). Mobile sources were
responsible for 74 percent of the noncancer (respiratory) risk from
outdoor air toxics in 1999. The majority of this risk was from
acrolein, and formaldehyde also contributed to the risk of respiratory
health effects. Although not included in NATA's estimates of noncancer
risk, PM from gasoline and diesel mobile sources contribute
significantly to the health effects associated with ambient PM.
It should be noted that the NATA modeling framework has a number of
limitations which prevent its use as the sole basis for setting
regulatory standards. These limitations and uncertainties are discussed
on the 1999 NATA Web site.\40\ Even so, this modeling framework is very
useful in identifying air toxic pollutants and sources of greatest
concern, setting regulatory priorities, and informing the decision
making process.
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\40\ U.S. EPA (2006) National-Scale Air Toxics Assessment for
1999. http://www.epa.gov/ttn/atw/nata1999.

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The following section provides a brief overview of air toxics which
are associated with nonroad engines, including locomotive and marine
diesel engines, and provides a discussion of the health risks
associated with each air toxic.
(a) Diesel Exhaust (DE)
Locomotive and marine diesel engine emissions include diesel
exhaust (DE), a complex mixture comprised of carbon dioxide, oxygen,
nitrogen, water vapor, carbon monoxide, nitrogen compounds, sulfur
compounds and numerous low-molecular-weight hydrocarbons. A number of
these gaseous hydrocarbon components are individually known to be toxic
including aldehydes, benzene and 1,3-butadiene. The diesel particulate
matter (DPM) present in diesel exhaust consists of fine particles (< 2.5
[mu]m), including a subgroup with a large number of ultrafine particles
(< 0.1 [mu]m). These particles have large surface area which makes them
an excellent medium for adsorbing organics and their small size makes
them highly respirable and able to reach the deep lung. Many of the
organic compounds present on the particles and in the gases are
individually known to have mutagenic and carcinogenic properties.
Diesel exhaust varies significantly in chemical composition and
particle sizes between different engine types (heavy-duty, light-duty),
engine operating conditions (idle, accelerate, decelerate), and fuel
formulations (high/low sulfur fuel). Also, there are emissions
differences between on-road and nonroad engines because the nonroad
engines are generally of older technology. This is especially true for
locomotive and marine diesel engines.\41\
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\41\ U.S. EPA (2002) Health Assessment Document for Diesel
Engine Exhaust. EPA/600/8-90/057F Office of Research and
Development, Washington, DC. Pp 1-1, 1-2. This document is available
electronically at http://cfpub.epa.gov/ncea/cfm/recordisplay.cfm?deid=29060.

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[[Page 15957]]

After being emitted in the engine exhaust, diesel exhaust undergoes
dilution as well as chemical and physical changes in the atmosphere.
The lifetime for some of the compounds present in diesel exhaust ranges
from hours to days.
(i) Diesel Exhaust: Potential Cancer Effect of Diesel Exhaust
In EPA's 2002 Diesel Health Assessment Document (Diesel HAD),\42\
diesel exhaust was classified as likely to be carcinogenic to humans by
inhalation at environmental exposures, in accordance with the revised
draft 1996/1999 EPA cancer guidelines. A number of other agencies
(National Institute for Occupational Safety and Health, the
International Agency for Research on Cancer, the World Health
Organization, California EPA, and the U.S. Department of Health and
Human Services) have made similar classifications. However, EPA also
concluded in the Diesel HAD that it is not possible currently to
calculate a cancer unit risk for diesel exhaust due to a variety of
factors that limit the current studies, such as limited quantitative
exposure histories in occupational groups investigated for lung cancer.
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\42\ U.S. EPA (2002) Health Assessment Document for Diesel
Engine Exhaust. EPA/600/8-90/057F Office of Research and
Development, Washington, DC. This document is available
electronically at http://cfpub.epa.gov/ncea/cfm/recordisplay.cfm?deid=29060.

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For the Diesel HAD, EPA reviewed 22 epidemiologic studies on the
subject of the carcinogenicity of workers exposed to diesel exhaust in
various occupations, finding increased lung cancer risk, although not
always statistically significant, in 8 out of 10 cohort studies and 10
out of 12 case-control studies within several industries, including
railroad workers. Relative risk for lung cancer associated with
exposure ranged from 1.2 to 1.5, although a few studies show relative
risks as high as 2.6. Additionally, the Diesel HAD also relied on two
independent meta-analyses, which examined 23 and 30 occupational
studies respectively, which found statistically significant increases
in smoking-adjusted relative lung cancer risk associated with diesel
exhaust, of 1.33 to 1.47. These meta-analyses demonstrate the effect of
pooling many studies and in this case show the positive relationship
between diesel exhaust exposure and lung cancer across a variety of
diesel exhaust-exposed occupations.\43\ \44\ \45\
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\43\ U.S. EPA (2002) Health Assessment Document for Diesel
Engine Exhaust. EPA/6008-90/057F Office of Research and Development,
Washington, DC. 9-11.
\44\ Bhatia, R., Lopipero, P., Smith, A. (1998) Diesel exposure
and lung cancer. Epidemiology 9(1):84-91.
\45\ Lipsett, M: Campleman, S; (1999) Occupational exposure to
diesel exhaust and lung cancer: a meta-analysis. Am J Public Health
80(7): 1009-1017.
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In the absence of a cancer unit risk, the Diesel HAD sought to
provide additional insight into the significance of the diesel exhaust-
cancer hazard by estimating possible ranges of risk that might be
present in the population. An exploratory analysis was used to
characterize a possible risk range by comparing a typical environmental
exposure level for highway diesel sources to a selected range of
occupational exposure levels. The occupationally observed risks were
then proportionally scaled according to the exposure ratios to obtain
an estimate of the possible environmental risk. A number of
calculations are needed to accomplish this, and these can be seen in
the EPA Diesel HAD. The outcome was that environmental risks from
diesel exhaust exposure could range from a low of 10-\4\ to
10-\5\ to as high as 10-\3\, reflecting the range
of occupational exposures that could be associated with the relative
and absolute risk levels observed in the occupational studies. Because
of uncertainties, the analysis acknowledged that the risks could be
lower than 10-\4\ or 10-\5\, and a zero risk from
diesel exhaust exposure was not ruled out.
Retrospective health studies of railroad workers have played an
important part in determining that diesel exhaust is a likely human
carcinogen. Key evidence of the diesel exhaust exposure linkage to lung
cancer comes from two retrospective case-control studies of railroad
workers which are discussed at length in the Diesel HAD.
(ii) Diesel Exhaust: Other Health Effects
Noncancer health effects of acute and chronic exposure to diesel
exhaust emissions are also of concern to the Agency. EPA derived an RfC
from consideration of four well-conducted chronic rat inhalation
studies showing adverse pulmonary effects. \46\ \47\ \48\ \49\ The RfC
is 5 [mu]g/m \3\ for diesel exhaust as measured by diesel PM. This RfC
does not consider allergenic effects such as those associated with
asthma or immunologic effects. There is growing evidence, discussed in
the Diesel HAD, that diesel exhaust can exacerbate these effects, but
the exposure-response data are presently lacking to derive an RfC. The
EPA Diesel HAD states, ``With DPM [diesel particulate matter] being a
ubiquitous component of ambient PM, there is an uncertainty about the
adequacy of the existing DE [diesel exhaust] noncancer database to
identify all of the pertinent DE-caused noncancer health hazards. (p. 9-19).
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\46\ Ishinishi, N; Kuwabara, N; Takaki, Y; et al. (1988) Long-
term inhalation experiments on diesel exhaust. In: Diesel exhaust
and health risks. Results of the HERP studies. Ibaraki, Japan:
Research Committee for HERP Studies; pp. 11-84.
\47\ Heinrich, U; Fuhst, R; Rittinghausen, S; et al. (1995)
Chronic inhalation exposure of Wistar rats and two different strains
of mice to diesel engine exhaust, carbon black, and titanium
dioxide. Inhal. Toxicol. 7:553-556.
\48\ Mauderly, JL; Jones, RK; Griffith, WC; et al. (1987) Diesel
exhaust is a pulmonary carcinogen in rats exposed chronically by
inhalation. Fundam. Appl. Toxicol. 9:208-221.
\49\ Nikula, KJ; Snipes, MB; Barr, EB; et al. (1995) Comparative
pulmonary toxicities and carcinogenicities of chronically inhaled
diesel exhaust and carbon black in F344 rats. Fundam. Appl. Toxicol.
25:80-94.
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Diesel exhaust has been shown to cause serious noncancer effects in
occupational exposure studies. One study of railroad workers and
electricians, cited in the Diesel HAD,\50\ found that exposure to
diesel exhaust resulted in neurobehavioral impairments in one or more
areas including reaction time, balance, blink reflex latency, verbal
recall, and color vision confusion indices. Pulmonary function tests
also showed that 10 of the 16 workers had airway obstruction and
another group of 10 of 16 workers had chronic bronchitis, chest pain,
tightness, and hyperactive airways. Finally, a variety of studies have
been published subsequent to the completion of the Diesel HAD. One such
study, published in 2006 \51\ found that railroad engineers and
conductors with diesel exhaust exposure from operating trains had an
increased incidence of chronic obstructive pulmonary disease (COPD)
mortality. The odds of COPD mortality increased with years on the job
so that those who had worked more than 16 years as an engineer or
conductor after 1959 had an increased risk of 1.61 (95% confidence
interval, 1.12--2.30). EPA is assessing the significance of this study
within the context of the broader literature.
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\50\ Kilburn (2000). See HAD Chapter 5-7.
\51\ Hart, JE, Laden F; Schenker, M.B.; and Garshick, E. Chronic
Obstructive Pulmonary Disease Mortality in Diesel-Exposed Railroad
Workers; Environmental Health Perspective July 2006: 1013-1016.

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[[Page 15958]]

(iii) Ambient PM_2.5 Levels and Exposure to Diesel Exhaust PM
The Diesel HAD also briefly summarizes health effects associated
with ambient PM and discusses the EPA's annual National Ambient Air
Quality Standard (NAAQS) of 15 [mu]g/m \3\. There is a much more
extensive body of human data showing a wide spectrum of adverse health
effects associated with exposure to ambient PM, of which diesel exhaust
is an important component. The PM_2.5 NAAQS is designed to
provide protection from the noncancer and premature mortality effects
of PM_2.5 as a whole, of which diesel PM is a constituent.
(iv) Diesel Exhaust PM Exposures
Exposure of people to diesel exhaust depends on their various
activities, the time spent in those activities, the locations where
these activities occur, and the levels of diesel exhaust pollutants in
those locations. The major difference between ambient levels of diesel
particulate and exposure levels for diesel particulate is that exposure
accounts for a person moving from location to location, proximity to
the emission source, and whether the exposure occurs in an enclosed
environment.
1. Occupational Exposures
Occupational exposures to diesel exhaust from mobile sources,
including locomotive engines and marine diesel engines, can be several
orders of magnitude greater than typical exposures in the non-
occupationally exposed population.
Over the years, diesel particulate exposures have been measured for
a number of occupational groups resulting in a wide range of exposures
from 2 to 1,280 [mu]g/m \3\ for a variety of occupations. Studies have
shown that miners and railroad workers typically have higher diesel
exposure levels than other occupational groups studied, including
firefighters, truck dock workers, and truck drivers (both short and
long haul).\52\ As discussed in the Diesel HAD, the National Institute
of Occupational Safety and Health (NIOSH) has estimated a total of
1,400,000 workers are occupationally exposed to diesel exhaust from on-
road and nonroad vehicles including locomotive and marine diesel engines.
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\52\ Diesel HAD Page 2-110, 8-12; Woskie, SR; Smith, TJ; Hammond, SK:
et al. (1988a) Estimation of the DE exposures of railroad workers: II.
National and historical exposures. Am J Ind Med 12:381-394.
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2. Elevated Concentrations and Ambient Exposures in Mobile Source-
Impacted Areas
Regions immediately downwind of rail yards and marine ports may
experience elevated ambient concentrations of directly-emitted
PM_2.5 from diesel engines. Due to the unique nature of rail
yards and marine ports, emissions from a large number of diesel engines
are concentrated in a small area. Furthermore, emissions occur at or
near ground level, allowing emissions of diesel engines to reach nearby
receptors without fully mixing with background air.
A recent study conducted by the California Air Resources Board
(CARB) examined the air quality impacts of railroad operations at the
J.R. Davis Rail Yard, the largest rail facility in the western United
States. \53\ The yard occupies 950 acres along a one-quarter mile wide
and four mile long section of land in Roseville, CA. The study
developed an emissions inventory for the facility for the year 2000 and
modeled ambient concentrations of diesel PM using a well-accepted
dispersion model (ISCST3). The study estimated substantially elevated
concentrations in an area 5,000 meters from the facility, with higher
concentrations closer to the rail yard. Using local meteorological
data, annual average contributions from the rail yard to ambient diesel
PM concentrations under prevailing wind conditions were 1.74, 1.18,
0.80, and 0.25 [mu]g/m \3\ at receptors located 200, 500, 1000, and
5000 meters from the yard, respectively. Several tens of thousands of
people live within the area estimated to experience substantial
increases in annual average ambient PM_2.5 as a result of
rail yard emissions.
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\53\ Hand, R.; Pingkuan, D.; Servin, A.; Hunsaker, L.; Suer, C.
(2004) Roseville rail yard study. California Air Resources Board.
[Online at http://www.arb.ca.gov/diesel/documents/rrstudy.htm].

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Another study from CARB evaluated air quality impacts of diesel
engine emissions within the Ports of Long Beach and Los Angeles in
California, one of the largest ports in the U.S.\54\ Like the earlier
rail yard study, the port study employed the ISCST3 dispersion model.
Also using local meteorological data, annual average concentrations
were substantially elevated over an area exceeding 200,000 acres.
Because the ports are located near heavily-populated areas, the
modeling indicated that over 700,000 people lived in areas with at
least 0.3 [mu]g/m3 of port-related diesel PM in ambient air,
about 360,000 people lived in areas with at least 0.6 [mu]g/m
3 of diesel PM, and about 50,000 people lived in areas with
at least 1.5 [mu]g/m 3 of ambient diesel PM directly from the port.
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\54\ Di, P.; Servin, A.; Rosenkranz, K.; Schwehr, B.; Tran, H.
(2006) Diesel particulate matter exposure assessment study for the
Ports of Los Angeles and Long Beach. California Air Resources Board.
[Online at http://www.arb.ca.gov/msprog/offroad/marinevess/marinevess.htm].

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Overall, while these studies focus on only two large marine port
and railroad facilities, they highlight the substantial contribution
these facilities make to elevated ambient concentrations in populated areas.
We have recently initiated a study to better understand the
populations that are living near rail yards and marine ports
nationally. As part of the study, a computer geographic information
system (GIS) is being used to identify the locations and property
boundaries of these facilities nationally, and to determine the size
and demographic characteristics of the population living near these
facilities. We anticipate that the results of this study will be
complete in 2007 and we intend to add this report to the public docket.
(a) Gaseous Air Toxics--Benzene, 1,3-butadiene, Formaldehyde,
Acetaldehyde, Acrolein, POM, Naphthalene
Locomotive and marine diesel engine exhaust emissions contribute to
ambient levels of other air toxics known or suspected as human or
animal carcinogens, or that have non-cancer health effects. These other
compounds include benzene, 1,3-butadiene, formaldehyde, acetaldehyde,
acrolein, polycyclic organic matter (POM), and naphthalene. All of
these compounds, except acetaldehyde, were identified as national or
regional risk drivers in the 1999 National-Scale Air Toxics Assessment
(NATA) and have significant inventory contributions from mobile
sources. That is, for a significant portion of the population, these
compounds pose a significant portion of the total cancer and noncancer
risk from breathing outdoor air toxics. The reductions in locomotive
and marine diesel engine emissions proposed in this rulemaking would
help reduce exposure to these harmful substances.
Air toxics can cause a variety of cancer and noncancer health
effects. A number of the mobile source air toxic pollutants described
in this section are known or likely to pose a cancer hazard in humans.
Many of these compounds also cause adverse noncancer health effects
resulting from chronic,\55\

[[Page 15959]]

subchronic,\56\ or acute \57\ inhalation exposures. These include
neurological, cardiovascular, liver, kidney, and respiratory effects as
well as effects on the immune and reproductive systems.
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\55\ Chronic exposure is defined in the glossary of the Integrated Risk
Information (IRIS) database (http://www.epa.gov/iris) as repeated
exposure by the oral, dermal, or inhalation route for more than
approximately 10 percent of the life span in humans (more than
approximately 90 days to 2 years in typically used laboratory animal
species).
\56\ Defined in the IRIS database as exposure to a substance
spanning approximately 10 percent of the lifetime of an organism.
\57\ Defined in the IRIS database as exposure by the oral,
dermal, or inhalation route for 24 hours or less.
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Benzene: The EPA's Integrated Risk Information (IRIS) database
lists benzene as a known human carcinogen (causing leukemia) by all
routes of exposure, and that exposure is associated with additional
health effects, including genetic changes in both humans and animals
and increased proliferation of bone marrow cells in
mice.58 59 60 EPA states in its IRIS database that data
indicate a causal relationship between benzene exposure and acute
lymphocytic leukemia and suggests a relationship between benzene
exposure and chronic non-lymphocytic leukemia and chronic lymphocytic
leukemia. A number of adverse noncancer health effects including blood
disorders, such as preleukemia and aplastic anemia, have also been
associated with long-term exposure to benzene.61 62 The most
sensitive noncancer effect observed in humans, based on current data,
is the depression of the absolute lymphocyte count in
blood.63 64 In addition, recent work, including studies
sponsored by the Health Effects Institute (HEI), provides evidence that
biochemical responses are occurring at lower levels of benzene exposure
than previously known.65 66 67 68 EPA's IRIS program has not
yet evaluated these new data.
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\58\ U.S. EPA. 2000. Integrated Risk Information System File for
Benzene. This material is available electronically at
http://www.epa.gov/iris/subst/0276.htm.
\59\ International Agency for Research on Cancer, IARC
monographs on the evaluation of carcinogenic risk of chemicals to
humans, Volume 29, Some industrial chemicals and dyestuffs,
International Agency for Research on Cancer, World Health
Organization, Lyon, France, p. 345-389, 1982.
\60\ Irons, R.D.; Stillman, W.S.; Colagiovanni, D.B.; Henry,
V.A. (1992) Synergistic action of the benzene metabolite
hydroquinone on myelopoietic stimulating activity of granulocyte/
macrophage colony-stimulating factor in vitro, Proc. Natl. Acad.
Sci. 89:3691-3695.
\61\ Aksoy, M. (1989). Hematotoxicity and carcinogenicity of
benzene. Environ. Health Perspect. 82:193-197.
\62\ Goldstein, B.D. (1988). Benzene toxicity. Occupational
medicine. State of the Art Reviews. 3:541-554.
\63\ Rothman, N., G.L. Li, M. Dosemeci, W.E. Bechtold, G.E.
Marti, Y.Z. Wang, M. Linet, L.Q. Xi, W. Lu, M.T. Smith, N. Titenko-
Holland, L.P. Zhang, W. Blot, S.N. Yin, and R.B. Hayes (1996)
Hematotoxicity among Chinese workers heavily exposed to benzene. Am.
J. Ind. Med. 29:236-246.
\64\ U.S. EPA 2002 Toxicological Review of Benzene (Noncancer
Effects). Environmental Protection Agency, Integrated Risk
Information System (IRIS), Research and Development, National Center
for Environmental Assessment, Washington, DC. This material is
available electronically at http://www.epa.gov/iris/subst/0276.htm.
\65\ Qu, O.; Shore, R.; Li, G.; Jin, X.; Chen, C.L.; Cohen, B.;
Melikian, A.; Eastmond, D.; Rappaport, S.; Li, H.; Rupa, D.;
Suramaya, R.; Songnian, W.; Huifant, Y.; Meng, M.; Winnik, M.; Kwok,
E.; Li, Y.; Mu, R.; Xu, B.; Zhang, X.; Li, K. (2003). HEI Report
115, Validation & Evaluation of Biomarkers in Workers Exposed to
Benzene in China.
\66\ Qu, Q., R. Shore, G. Li, X. Jin, L.C. Chen, B. Cohen, et
al. (2002). Hematological changes among Chinese workers with a broad
range of benzene exposures. Am. J. Industr. Med. 42: 275-285.
\67\ Lan, Qing, Zhang, L., Li, G., Vermeulen, R., et al. (2004).
Hematotoxically in Workers Exposed to Low Levels of Benzene. Science
306: 1774-1776.
\68\ Turtletaub, K.W. and Mani, C. (2003). Benzene metabolism in
rodents at doses relevant to human exposure from Urban Air. Research
Reports Health Effect Inst. Report No.113.
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1,3-Butadiene: EPA has characterized 1,3-butadiene as carcinogenic
to humans by inhalation.69 70 The specific mechanisms of
1,3-butadiene-induced carcinogenesis are unknown. However, it is
virtually certain that the carcinogenic effects are mediated by
genotoxic metabolites of 1,3-butadiene. Animal data suggest that
females may be more sensitive than males for cancer effects; while
there are insufficient data in humans from which to draw conclusions
about sensitive subpopulations. 1,3-Butadiene also causes a variety of
reproductive and developmental effects in mice; no human data on these
effects are available. The most sensitive effect was ovarian atrophy
observed in a lifetime bioassay of female mice.\71\
Formaldehyde: Since 1987, EPA has classified formaldehyde as a
probable human carcinogen based on evidence in humans and in rats,
mice, hamsters, and monkeys.\72\ EPA is currently reviewing recently
published epidemiological data. For instance, recently released
research conducted by the National Cancer Institute (NCI) found an
increased risk of nasopharyngeal cancer and lymphohematopoietic
malignancies such as leukemia among workers exposed to
formaldehyde.73 74 NCI is currently performing an update of
these studies. A recent National Institute of Occupational Safety and
Health (NIOSH) study of garment workers also found increased risk of
death due to leukemia among workers exposed to formaldehyde.\75\ Based
on the developments of the last decade, in 2004, the working group of
the International Agency for Research on Cancer (IARC) concluded that
formaldehyde is carcinogenic to humans (Group 1), on the basis of
sufficient evidence in humans and sufficient evidence in experimental
animals--a higher classification than previous IARC evaluations.
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\69\ U.S. EPA. 2002. Health Assessment of 1,3-Butadiene. Office
of Research and Development, National Center for Environmental
Assessment, Washington Office, Washington, DC. Report No. EPA600-P-
98-001F. This document is available electronically at
http://www.epa.gov/iris/supdocs/buta-sup.pdf.
\70\ U.S. EPA. 2002. ``Full IRIS Summary for 1,3-butadiene
(CASRN 106-99-0)'' Environmental Protection Agency, Integrated Risk
Information System (IRIS), Research and Development, National Center
for Environmental Assessment, Washington, DC.
http://www.epa.gov/iris/subst/0139.htm.
\71\ Bevan, C.; Stadler, J.C.; Elliot, G.S.; et al. (1996)
Subchronic toxicity of 4-vinylcyclohexene in rats and mice by
inhalation. Fundam. Appl. Toxicol. 32:1-10.
\72\ U.S. EPA (1987). Assessment of Health Risks to Garment
Workers and Certain Home Residents from Exposure to Formaldehyde,
Office of Pesticides and Toxic Substances, April 1987.
\73\ Hauptmann, M.; Lubin, J.H.; Stewart, P.A.; Hayes, R.B.;
Blair, A. 2003. Mortality from lymphohematopoietic malignancies
among workers in formaldehyde industries. Journal of the National
Cancer Institute 95: 1615-1623.
\74\ Hauptmann, M..; Lubin, J.H.; Stewart, P.A.; Hayes, R.B.;
Blair, A. 2004. Mortality from solid cancers among workers in
formaldehyde industries. American Journal of Epidemiology 159: 1117-1130.
\75\ Pinkerton, L.E. 2004. Mortality among a cohort of garment
workers exposed to formaldehyde: an update. Occup. Environ. Med. 61: 193-200.
---------------------------------------------------------------------------

Formaldehyde exposure also causes a range of noncancer health
effects, including irritation of the eyes (tearing of the eyes and
increased blinking) and mucous membranes.
Acetaldehyde: Acetaldehyde is classified in EPA's IRIS database as
a probable human carcinogen, based on nasal tumors in rats, and is
considered toxic by the inhalation, oral, and intravenous routes.\76\
The primary acute effect of exposure to acetaldehyde vapors is
irritation of the eyes, skin, and respiratory tract.\77\ The agency is
currently conducting a reassessment of the health hazards from
inhalation exposure to acetaldehyde.
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\76\ U.S. EPA. 1988. Integrated Risk Information System File of
Acetaldehyde. Research and Development, National Center for
Environmental Assessment, Washington, DC. This material is available
electronically at http://www.epa.gov/iris/subst/0290.htm.
\77\ U.S. EPA. 1988. Integrated Risk Information System File of
Acetaldehyde. Research and Development, National Center for
Environmental Assessment, Washington, DC. This material is available
electronically at http://www.epa.gov/iris/subst/0290.htm.

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Acrolein: Acrolein is intensely irritating to humans when inhaled,
with acute exposure resulting in upper respiratory tract irritation and
congestion. EPA determined in 2003 using the 1999 draft cancer
guidelines that the human carcinogenic potential of acrolein could not
be determined because the available data were inadequate. No
information was

[[Page 15960]]

available on the carcinogenic effects of acrolein in humans and the
animal data provided inadequate evidence of carcinogenicity.\78\
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\78\ U.S. EPA. 2003. Integrated Risk Information System File of
Acrolein. Research and Development, National Center for
Environmental Assessment, Washington, DC. This material is available
electronically at http://www.epa.gov/iris/subst/0364.htm.

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Polycyclic Organic Matter (POM): POM is generally defined as a
large class of organic compounds which have multiple benzene rings and
a boiling point greater than 100 degrees Celsius. Many of the compounds
included in the class of compounds known as POM are classified by EPA
as probable human carcinogens based on animal data. One of these
compounds, naphthalene, is discussed separately below.
Recent studies have found that maternal exposures to PAHs in a
population of pregnant women were associated with several adverse birth
outcomes, including low birth weight and reduced length at birth, as
well as impaired cognitive development at age three.79 80
EPA has not yet evaluated these recent studies.
---------------------------------------------------------------------------

\79\ Perera, F.P.; Rauh, V.; Tsai, W-Y.; et al. (2002) Effect of
transplacental exposure to environmental pollutants on birth
outcomes in a multiethnic population. Environ Health Perspect. 111:
201-205.
\80\ Perera, F.P.; Rauh, V.; Whyatt, R.M.; Tsai, W.Y.; Tang, D.;
Diaz, D.; Hoepner, L.; Barr, D.; Tu, Y.H.; Camann, D.; Kinney, P.
(2006) Effect of prenatal exposure to airborne polycyclic aromatic
hydrocarbons on neurodevelopment in the first 3 years of life among
inner-city children. Environ Health Perspect 114: 1287-1292.
---------------------------------------------------------------------------

Naphthalene: Naphthalene is found in small quantities in gasoline
and diesel fuels but is primarily a product of combustion. EPA recently
released an external review draft of a reassessment of the inhalation
carcinogenicity of naphthalene.\81\ The draft reassessment recently
completed external peer review.\82\ Based on external peer review
comments, additional analyses are being considered. California EPA has
released a new risk assessment for naphthalene, and the IARC has
reevaluated naphthalene and re-classified it as Group 2B: possibly
carcinogenic to humans.\83\ Naphthalene also causes a number of chronic
non-cancer effects in animals, including abnormal cell changes and
growth in respiratory and nasal tissues.\84\
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\81\ U.S. EPA. 2004. Toxicological Review of Naphthalene
(Reassessment of the Inhalation Cancer Risk), Environmental
Protection Agency, Integrated Risk Information System, Research and
Development, National Center for Environmental Assessment,
Washington, DC. This material is available electronically at
http://www.epa.gov/iris/subst/0436.htm.
\82\ Oak Ridge Institute for Science and Education. (2004).
External Peer Review for the IRIS Reassessment of the Inhalation
Carcinogenicity of Naphthalene. August 2004.
http://cfpub2.epa.gov/ncea/cfm/recordisplay.cfm?deid=86019.
\83\ International Agency for Research on Cancer (IARC). (2002).
Monographs on the Evaluation of the Carcinogenic Risk of Chemicals
for Humans. Vol. 82. Lyon, France.
\84\ U.S. EPA. 1998. Toxicological Review of Naphthalene,
Environmental Protection Agency, Integrated Risk Information System,
Research and Development, National Center for Environmental
Assessment, Washington, DC. This material is available
electronically at http://www.epa.gov/iris/subst/0436.htm.

---------------------------------------------------------------------------

In addition to reducing substantial amounts of NO_X and
PM_2.5 emissions from locomotive and marine diesel engines,
the standards being proposed today would also reduce air toxics emitted
from these engines. This will help mitigate some of the adverse health
effects associated with operation of these engines.

C. Other Environmental Effects

There is a number of public welfare effects associated with the
presence of ozone and PM_2.5 in the ambient air. In this
section we discuss the impact of PM_2.5 on visibility and
materials and the impact of ozone on plants, including trees, agronomic
crops and urban ornamentals.
(1) Visibility
Visibility can be defined as the degree to which the atmosphere is
transparent to visible light.\85\ Visibility impairment manifests in
two principal ways: as local visibility impairment and as regional
haze.\86\ Local visibility impairment may take the form of a localized
plume, a band or layer of discoloration appearing well above the
terrain as a result of complex local meteorological conditions.
Alternatively, local visibility impairment may manifest as an urban
haze, sometimes referred to as a ``brown cloud''. This urban haze is
largely caused by emissions from multiple sources in the urban areas
and is not typically attributable to only one nearby source or to long-
range transport. The second type of visibility impairment, regional
haze, usually results from multiple pollution sources spread over a
large geographic region. Regional haze can impair visibility in large
regions and across states.
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\85\ National Research Council, 1993. Protecting Visibility in
National Parks and Wilderness Areas. National Academy of Sciences
Committee on Haze in National Parks and Wilderness Areas. National
Academy Press, Washington, DC. This document is available in Docket
EPA-HQ-OAR-2005-0036. This book can be viewed on the National
Academy Press Web site at http://www.nap.edu/books/0309048443/html.

\86\ See discussion in U.S. EPA, National Ambient Air Quality
Standards for Particulate Matter; Proposed Rule; January 17, 2006,
Vol 71 p 2676. This information is available electronically at
http://epa.gov/fedrgstr/EPA-AIR/2006/January/Day-17/a177.pdf.
\87\ U.S. EPA (2004). Air Quality Criteria for Particulate
Matter (Oct 2004), Volume I Document No. EPA600/P-99/002aF and
Volume II Document No. EPA600/P-99/002bF. This document is available
in Docket EPA-HQ-OAR-2005-0036.
\88\ U.S. EPA (2005). Review of the National Ambient Air Quality
Standard for Particulate Matter: Policy Assessment of Scientific and
Technical Information, OAQPS Staff Paper. EPA-452/R-05-005. This
document is available in Docket EPA-HQ-OAR-2005-0036.
---------------------------------------------------------------------------

Visibility is important because it has direct significance to
people's enjoyment of daily activities in all parts of the country.
Individuals value good visibility for the well-being it provides them
directly, where they live and work, and in places where they enjoy
recreational opportunities. Visibility is also highly valued in
significant natural areas such as national parks and wilderness areas
and special emphasis is given to protecting visibility in these areas.
For more information on visibility see the final 2004 PM AQCD as well
as the 2005 PM Staff Paper.87 88

[[Page 15961]]

Fine particles are the major cause of reduced visibility in parts
of the United States. EPA is pursuing a two-part strategy to address
visibility. First, to address the welfare effects of PM on visibility,
EPA set secondary PM_2.5 standards which would act in
conjunction with the establishment of a regional haze program. In
setting this secondary standard EPA concluded that PM_2.5
causes adverse effects on visibility in various locations, depending on
PM concentrations and factors such as chemical composition and average
relative humidity. Second, section 169 of the Clean Air Act provides
additional authority to address existing visibility impairment and
prevent future visibility impairment in the 156 national parks, forests
and wilderness areas categorized as mandatory class I federal areas (62
FR 38680-81, July 18, 1997).\89\ In July 1999 the regional haze rule
(64 FR 35714) was put in place to protect the visibility in mandatory
class I federal areas. Visibility can be said to be impaired in both
PM_2.5 nonattainment areas and mandatory class I federal
areas.\90\
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\89\ These areas are defined in section 162 of the Act as those
national parks exceeding 6,000 acres, wilderness areas and memorial
parks exceeding 5,000 acres, and all international parks which were
in existence on August 7, 1977.
\90\ As mentioned above, the EPA has recently proposed to amend
the PM NAAQS (71 FR 2620, Jan. 17, 2006). The proposal would set the
secondary NAAQS equal to the primary standards for both
PM_2.5 and PM₁₀_-_2.5. EPA
also is taking comment on whether to set a separate PM_2.5
standard, designed to address visibility (principally in urban
areas), on potential levels for that standard within a range of 20
to 30 [mu]g/m\3\, and on averaging times for the standard within a
range of four to eight daylight hours.
---------------------------------------------------------------------------

Locomotives and marine engines contribute to visibility concerns in
these areas through their primary PM_2.5 emissions and their
NO_X emissions which contribute to the formation of secondary
PM_2.5.
Current Visibility Impairment
Recently designated PM_2.5 nonattainment areas indicate
that, as of March 2, 2006, almost 90 million people live in
nonattainment areas for the 1997 PM_2.5 NAAQS. Thus, at least
these populations would likely be experiencing visibility impairment,
as well as many thousands of individuals who travel to these areas. In
addition, while visibility trends have improved in mandatory class I
federal areas the most recent data show that these areas continue to
suffer from visibility impairment. In summary, visibility impairment is
experienced throughout the U.S., in multi-state regions, urban areas,
and remote mandatory class I federal areas.\91\ \92\ The mandatory
federal class I areas are listed in Chapter 2 of the draft RIA for this
action. The areas that have design values above the 1997
PM_2.5 NAAQS are also listed in Chapter 2 of the draft RIA
for this action.
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\91\ US EPA, Air Quality Designations and Classifications for
the Fine Particles (PM_2.5) National Ambient Air Quality
Standards, December 17, 2004. (70 FR 943, Jan 5. 2005) This document
is also available on the Web at: http://www.epa.gov/pmdesignations/.
\92\ US EPA. Regional Haze Regulations, July 1, 1999. (64 FR
35714, July 1, 1999).
---------------------------------------------------------------------------

Future Visibility Impairment

Recent modeling for this proposed rule was used to project
visibility conditions in the 116 mandatory class I federal areas across
the U.S. in 2020 and 2030 resulting from the proposed locomotive and
marine diesel engine standards. The results suggest that improvement in
visibility would occur in all class I federal areas although areas
would continue to have annual average deciview levels above background
in 2020 and 2030. Table II-2 groups class I federal areas by regions
and illustrates that regardless of geographic area, reductions in
PM_2.5 emissions from this rule would benefit visibility in
each region of the U.S. in mandatory class I federal areas.

Table II-2.--SUmmary of Modeled 2030 Visibility Conditions in Mandatory Class I Federal Areas
[Annual average deciview]
----------------------------------------------------------------------------------------------------------------
Predicted 2030
visibility Predicted 2030 Change in annual
Region baseline w/o rule visibility with average deciview
rule rule control
----------------------------------------------------------------------------------------------------------------
Eastern
----------------------------------------------------------------------------------------------------------------
Southeast........................................... 17.52 17.45 .07
Northeast/Midwest................................... 14.85 14.80 .05
----------------------------------------------------------------------------------------------------------------
Western
----------------------------------------------------------------------------------------------------------------
Southwest........................................... 9.36 9.32 .04
West (CA-NV-UT)..................................... 9.99 9.92 .07
Rocky Mountain...................................... 8.37 8.33 .04
Northwest........................................... 9.11 9.05 .06
National Class I Area Average....................... 10.97 10.91 .06
----------------------------------------------------------------------------------------------------------------
Notes:
(a) Background visibility conditions differ by regions: Eastern natural background is 9.5 deciview (or visual
range of 150 kilometers) and the West natural background is 5.3 deciview (or visual range of 230 kilometers).
(b) The results average visibility conditions for mandatory Class I Federal areas in the regions.
(c) The results illustrate the type of visibility improvements for the primary control options. The proposal
differs based on updated information; however, we believe that the net results would approximate future PM
emissions.

(2) Plant and Ecosystem Effects of Ozone
Ozone contributes to many environmental effects, with impacts to
plants and ecosystems being of most concern. Ozone can produce both
acute and chronic injury in sensitive species depending on the
concentration level and the duration of the exposure. Ozone effects
also tend to accumulate over the growing season of the plant, so that
even lower concentrations experienced for a longer duration have the
potential to create chronic stress on vegetation. Ozone damage to
plants includes visible injury to leaves and a reduction in food
production through impaired photosynthesis, both of which can lead to
reduced crop yields, forestry production, and use of sensitive
ornamentals in landscaping. In addition, the reduced food production in
plants and subsequent reduced root growth and storage below ground, can
result in

[[Page 15962]]

other, more subtle plant and ecosystems impacts. These include
increased susceptibility of plants to insect attack, disease, harsh
weather, interspecies competition and overall decreased plant vigor.
The adverse effects of ozone on forest and other natural vegetation can
potentially lead to species shifts and loss from the affected
ecosystems, resulting in a loss or reduction in associated ecosystem
goods and services. Lastly, visible ozone injury to leaves can result
in a loss of aesthetic value in areas of special scenic significance
like national parks and wilderness areas. The final 2006 Criteria
Document presents more detailed information on ozone effects on
vegetation and ecosystems.
As discussed above, locomotive and marine diesel engine emissions
of NO_X contribute to ozone and therefore the proposed
NO_X standards will help reduce crop damage and stress on
vegetation from ozone.
(3) Acid Deposition
Acid deposition, or acid rain as it is commonly known, occurs when
NO_X and SO₂ react in the atmosphere with water,
oxygen and oxidants to form various acidic compounds that later fall to
earth in the form of precipitation or dry deposition of acidic
particles. It contributes to damage of trees at high elevations and in
extreme cases may cause lakes and streams to become so acidic that they
cannot support aquatic life. In addition, acid deposition accelerates
the decay of building materials and paints, including irreplaceable
buildings, statues, and sculptures that are part of our nation's
cultural heritage.
The proposed NO_X standards would help reduce acid
deposition, thereby helping to reduce acidity levels in lakes and
streams throughout the country and helping accelerate the recovery of
acidified lakes and streams and the revival of ecosystems adversely
affected by acid deposition. Reduced acid deposition levels will also
help reduce stress on forests, thereby accelerating reforestation
efforts and improving timber production. Deterioration of historic
buildings and monuments, vehicles, and other structures exposed to acid
rain and dry acid deposition also will be reduced, and the costs borne
to prevent acid-related damage may also decline. While the reduction in
nitrogen acid deposition will be roughly proportional to the reduction
in NO_X emissions, the precise impact of this rule will
differ across different areas.
(4) Eutrophication and Nitrification
The NO_X standards proposed in this action will help
reduce the airborne nitrogen deposition that contributes to
eutrophication of watersheds, particularly in aquatic systems where
atmospheric deposition of nitrogen represents a significant portion of
total nitrogen loadings.
Eutrophication is the accelerated production of organic matter,
particularly algae, in a water body. This increased growth can cause
numerous adverse ecological effects and economic impacts, including
nuisance algal blooms, dieback of underwater plants due to reduced
light penetration, and toxic plankton blooms. Algal and plankton blooms
can also reduce the level of dissolved oxygen, which can adversely
affect fish and shellfish populations. In recent decades, human
activities have greatly accelerated nutrient impacts, such as nitrogen
and phosphorus, causing excessive growth of algae and leading to
degraded water quality and associated impairment of fresh water and
estuarine resources for human uses.\93\
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\93\ Deposition of Air Pollutants to the Great Waters, Third
Report to Congress, June 2000, EPA-453/R-00-005. This document can
be found in Docket No. OAR-2002-0030, Document No. OAR-2002-0030-
0025. It is also available at
http://www.epa.gov/oar/oaqps/gr8water/3rdrpt/obtain.html.

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Severe and persistent eutrophication often directly impacts human
activities. For example, losses in the nation's fishery resources may
be directly caused by fish kills associated with low dissolved oxygen
and toxic blooms. Declines in tourism occur when low dissolved oxygen
causes noxious smells and floating mats of algal blooms create
unfavorable aesthetic conditions. Risks to human health increase when
the toxins from algal blooms accumulate in edible fish and shellfish,
and when toxins become airborne, causing respiratory problems due to
inhalation. According to the NOAA report, more than half of the
nation's estuaries have moderate to high expressions of at least one of
these symptoms `` an indication that eutrophication is well developed
in more than half of U.S. estuaries.\94\
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\94\ Bricker, Suzanne B., et al. National Estuarine
Eutrophication Assessment, Effects of Nutrient Enrichment in the
Nation's Estuaries, National Ocean Service, National Oceanic and
Atmospheric Administration, September, 1999.
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(5) Materials Damage and Soiling
The deposition of airborne particles can reduce the aesthetic
appeal of buildings and culturally important articles through soiling,
and can contribute directly (or in conjunction with other pollutants)
to structural damage by means of corrosion or erosion.\95\ Particles
affect materials principally by promoting and accelerating the
corrosion of metals, by degrading paints, and by deteriorating building
materials such as concrete and limestone. Particles contribute to these
effects because of their electrolytic, hygroscopic, and acidic
properties, and their ability to adsorb corrosive gases (principally
sulfur dioxide). The rate of metal corrosion depends on a number of
factors, including the deposition rate and nature of the pollutant; the
influence of the metal protective corrosion film; the amount of
moisture present; variability in the electrochemical reactions; the
presence and concentration of other surface electrolytes; and the
orientation of the metal surface.
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\95\ U.S EPA (2005). Review of the National Ambient Air Quality
Standards for Particulate Matter: Policy Assessment of Scientific
and Technical Information, OAQPS Staff Paper. This document is
available in Docket EPA-HQ-OAR-2005-0036.
---------------------------------------------------------------------------

The PM_2.5 standards proposed in this action will help
reduce the airborne particles that contribute to materials damage and
soiling.

D. Other Criteria Pollutants Affected by This NPRM

Locomotive and marine diesel engines account for about 1 percent of
the mobile sources carbon monoxide (CO) inventory. Carbon monoxide (CO)
is a colorless, odorless gas produced through the incomplete combustion
of carbon-based fuels. The current primary NAAQS for CO are 35 ppm for
the 1-hour average and 9 ppm for the 8-hour average. These values are
not to be exceeded more than once per year. As of October 2006, there
are 15.5 million people living in 6 areas (10 counties) that are
designated as nonattainment for CO.
Carbon monoxide enters the bloodstream through the lungs, forming
carboxyhemoglobin and reducing the delivery of oxygen to the body's
organs and tissues. The health threat from CO is most serious for those
who suffer from cardiovascular disease, particularly those with angina
or peripheral vascular disease. Healthy individuals also are affected,
but only at higher CO levels. Exposure to elevated CO levels is
associated with impairment of visual perception, work capacity, manual
dexterity, learning ability and performance of complex tasks. Carbon
monoxide also contributes to ozone nonattainment since carbon monoxide
reacts photochemically in the atmosphere to form ozone. Additional
information on CO related health effects

[[Page 15963]]

can be found in the Air Quality Criteria for Carbon Monoxide.\96\
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\96\ U.S. EPA (2000). Air Quality Criteria for Carbon Monoxide,
EPA/600/P-99/001F. This document is available in Docket EPA-HQ-OAR-
2004-0008.
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E. Emissions From Locomotive and Marine Diesel Engines

(1) Overview
The engine standards being proposed in this rule would affect
emissions of particulate matter (PM_2.5), oxides of nitrogen
(NO_X), volatile organic compounds (VOCs), and air toxics.
Carbon monoxide is not specifically targeted in this proposal although
the technologies applied to control these other pollutants are expected
to also reduce CO emissions.
Locomotive and marine diesel engine emissions are expected to
continue to be a significant part of the mobile source emissions
inventory both nationally and in ozone and PM_2.5
nonattainment areas in the coming years. In the absence of new
emissions standards, we expect overall emissions from these engines to
decrease modestly over the next ten to fifteen years than remain
relatively flat through 2025 due to existing regulations such as lower
fuel sulfur requirements, the phase in of locomotive and marine diesel
Tier 1 and Tier 2 engine standards, and the Tier 0 locomotive
remanufacturing requirements. Beginning thereafter, emission
inventories from these engines would once again begin increasing due to
growth in the locomotive and marine sectors. Under today's proposed
standards, by 2030, annual NO_X emissions from these engines
would be reduced by 765,000 tons, PM_2.5 emissions by 28,000
tons, and VOC emissions by 42,000 tons.
In this section we first present base case emissions inventory
contributions for locomotive and marine diesel engines and other mobile
sources assuming no further emission controls beyond those already in
place. The 2001 inventory numbers were developed and used as an input
into our air quality modeling. Individual sub-sections which follow
discuss PM_2.5, NO_X, and VOC pollutants, in terms
of expected emission reductions associated with the proposed standards.
The tables and figures illustrate the Agency's analysis of current and
future emissions contributions from locomotive and marine diesel engines.
(2) Estimated Inventory Contribution
Locomotive and marine diesel engine emissions contribute to
nationwide PM, NO_X, VOC, CO, and air toxics inventories. Our
current baseline and future year estimates for NO_X and
PM_2.5 inventories (50-state) are set out in Tables II-3 and
II-4. Based on our analysis undertaken for this rulemaking, we estimate
that in 2001 locomotives and marine diesel engines contributed almost
60,000 tons (18 percent) to the national mobile source diesel
PM_2.5 inventory and about 2.0 million tons (16 percent) to
the mobile source NO_X inventory. In 2030, absent the
standards proposed today, these engines would contribute about 50,000
tons (65 percent) to the mobile source diesel PM_2.5
inventory and almost 1.6 million tons (35 percent) to the mobile source
NO_X inventory.
The national locomotives and marine diesel engine PM_2.5
and NO_X inventories in 2030 would be roughly twice as large
as the combined PM_2.5 and NO_X inventories from
on-highway diesel and land-based nonroad diesel engines. In absolute
terms--locomotives and marine diesel engines, in 2030, would annually
emit 22,000 more tons of PM_2.5 and 890,000 more tons of
NO_X than all highway and nonroad diesels combined. This
occurs because EPA has already taken steps to bring engine emissions
from both on-highway and nonroad diesels to near-zero levels, while
locomotives and marine diesel engines continue to meet relatively
modest emission requirements. Table II-4 shows that in 2001 the land-
based nonroad diesel category contributed about 160,000 tons of
PM_2.5 emissions and by 2030 they drop to under 18,000 tons.
Likewise, in 2001, annual PM_2.5 emissions from highway
diesel engines totaled about 110,000 tons falling in 2030 to about
10,000 tons. Table II-3 shows a similar downward trend occurring for
annual NO_X emissions. In 2001, NO_X emissions from
highway diesel engines' amounted to over 3.7 million tons but by 2030
they fall to about 260,000 tons. Finally, land-based nonroad diesels in
2001 emitted over 1.5 million tons of NO_X but by 2030 these
emissions drop to approximately 430,000 tons.
Marine diesel engine and locomotive inventories were developed
using multiple methodologies. Chapter 3 of the draft RIA provides a
detailed explanation of our approach. In summary, the quality of data
available for locomotive inventories made it possible to develop more
detailed estimates of fleet composition and emission rates than we have
previously done. Locomotive emissions were calculated based on
estimated current and projected fuel consumption rates. Emissions were
calculated separately for the following locomotive categories: line-
haul locomotives in large railroads, switching locomotives in large
railroads (including Class II/III switch railroads owned by Class I
railroads), other line-haul locomotives (i.e., local and regional
railroads), other switch/terminal locomotives, and passenger
locomotives. Our inventories for marine diesel engines were created
using the inventory for marine diesel engines up to 30 liters per
cylinder displacement including recreational, commercial, and auxiliary
applications was developed by using a methodology based on engine
population, hours of use, average engine loads, and in-use emissions
factors.

Table II-3.--Nationwide Annual NOX Baseline Emission Levels
--------------------------------------------------------------------------------------------------------------------------------------------------------
2001 2030
----------------------------------------------------------------------------------------
Percent
Category of
NOX short tons Percent of Percent of NOX Percent of total
mobile source total mobile source short
tons
--------------------------------------------------------------------------------------------------------------------------------------------------------
Locomotive..................................................... 1,118,786 9.0 5.1 854,226 19.0 8.1
Recreational Marine Diesel..................................... 40,437 0.3 0.2 48,155 1.1 0.5
Commercial Marine (C1 & C2).................................... 833,963 6.7 3.8 679,973 15.1 6.4
Land-Based Nonroad Diesel...................................... 1,548,236 12.5 7.1 434,466 9.7 4.1
Commercial Marine (C3)*........................................ 224,100 1.8 1.0 531,641 11.8 5.0
Small Nonroad SI............................................... 100,319 0.8 0.5 114,287 2.5 1.1
Recreational Marine SI......................................... 42,252 0.3 0.2 92,188 2.1 0.9
SI Recreational Vehicles....................................... 5,488 0.0 0.0 20,136 0.4 0.2
Large Nonroad SI (>25hp)....................................... 321,098 2.6 1.5 46,253 1.0 0.4

[[Page 15964]]

Aircraft....................................................... 83,764 0.7 0.4 118,740 2.6 1.1
Total Off Highway.............................................. 4,318,443 34.8 19.8 2,940,066 65.5 27.7
Highway Diesel................................................. 3,750,886 30.2 17.2 260,915 5.8 2.5
Highway non-diesel............................................. 4,354,430 35.0 20.0 1,289,780 28.7 12.2
Total Highway.................................................. 8,105,316 65.2 37.2 1,550,695 34.5 14.6
Total Diesel (distillate) Mobile............................... 7,292,308 58.7 33.5 2,277,735 50.7 21.5
Total Mobile Sources........................................... 12,423,758 100 57.0 4,490,761 100 42.4
Stationary Point and Area Sources.............................. 9,355,659 - 43.0 6,111,866 - 57.6
Total Man-Made Sources......................................... 21,779,418 - 100 10,602,627 - 100
--------------------------------------------------------------------------------------------------------------------------------------------------------
* This category includes emissions from Category 3 (C3) propulsion engines and C2/3 auxiliary engines used on ocean-going vessels.

Table II-4.--Nationwide Annual PM2.5 Baseline Emission Levels
--------------------------------------------------------------------------------------------------------------------------------------------------------
2001 2030
-------------------------------------------------------------------------------------------------
Category PM2.5 short Percent of Percent of PM2.5 short Percent of Percent of
tons diesel mobile mobile source tons diesel mobile mobile source
--------------------------------------------------------------------------------------------------------------------------------------------------------
Locomotive............................................ 29,660 8.9 6.36 25,109 32.2 10.01
Recreational Marine Diesel............................ 1,096 0.3 0.24 1,141 1.5 0.45
Commercial Marine (C1 & C2)........................... 28,728 8.6 6.16 23,758 30.5 9.47
Land-Based Nonroad Diesel............................. 164,180 49.2 35.2 17,934 23.0 7.1
Commercial Marine (C3)................................ 20,023 ............... 4.30 52,682 ............... 20.99
Small Nonroad SI...................................... 25,575 ............... 5.5 35,761 ............... 14.3
Recreational Marine SI................................ 17,101 ............... 3.7 6,378 ............... 2.5
SI Recreational Vehicles.............................. 12,301 ............... 2.6 9,953 ............... 4.0
Large Non road SI (>25hp)............................. 1,610 ............... 0.3 2,844 ............... 1.1
Aircraft.............................................. 5,664 ............... 1.22 8,569 ............... 3.41
Total Off Highway..................................... 305,939 ............... 65.6 184,129 ............... 73.4
Highway Diesel........................................ 109,952 33.0 23.6 10,072 12.9 4.0
Highway non-diesel.................................... 50,277 ............... 10.8 56,734 ............... 22.6
Total Highway......................................... 160,229 ............... 34.4 66,806 ............... 26.6
Total Diesel (distillate) Mobile...................... 333,618 100 71.6 78,014 100 31.1
Total Mobile Sources.................................. 466,168 ............... 100 250,934 ............... 100
Stationary Point and Area Sources Diesel.............. 3,189 ............... .............. 2,865 ............... ..............
Stationary Point and Areas Sources non-diesel......... 1,963,264 ............... .............. 1,817,722 ............... ..............
Total Stationary Point and Area Sources............... 1,966,453 ............... .............. 1,820,587 ............... ..............
Total Man-Made Sources............................ 2,432,621 ............... .............. 2,071,521 ............... ..............
--------------------------------------------------------------------------------------------------------------------------------------------------------

(3) PM_2.5 Emission Reductions
In 2001 annual emissions from locomotive and marine diesel engines
totaled about 60,000 tons. Table II-4 shows the distribution of these
PM_2.5 emissions: locomotives contributed about 30,000 tons,
recreational marine diesel roughly 1,000 tons, and commercial marine
diesel (C1 and C2) 29,000 tons. Due to current standards, annual
PM_2.5 emissions from these engines drop to 50,000 tons in
2030 with roughly proportional emission reductions occurring in both
the locomotive and commercial marine diesel categories while the
recreational marine diesel category experiences a slight increase in
PM_2.5 emissions. Both Tables II-5 and Figure II-4 show
PM_2.5 emissions nearly flat through 2030 before beginning to
rise again due to growth in these sectors.
Table II-5 shows how the proposed rule would begin reducing
PM_2.5 emissions from the current national inventory baseline
starting in 2015 when annual reductions of 7,000 tons would occur. By
2020 that number would grow to 15,000 tons of PM_2.5, by 2030
to 28,000 annual tons, and reductions would continue to grow through
2040 to about 39,000 tons of PM_2.5 annually.

Table II-5.--Locomotive and Marine Diesel PM2.5 Emissions
[Short tons/year]
------------------------------------------------------------------------
2015 2020 2030 2040
------------------------------------------------------------------------
Without Proposed Rule....... 51,000 50,000 50,000 54,000
With Proposed Rule.......... 44,000 35,000 22,000 15,000
Reductions From Proposed 7,000 15,000 28,000 39,000
Rule.......................
------------------------------------------------------------------------

[[Page 15965]]
[GRAPHIC]
[TIFF OMITTED] TP03AP07.003

Although this proposed rule results in large nationwide
PM_2.5 inventory reductions, it would also help urban areas
that have significant locomotive and marine diesel engine emissions in
their inventories. Table II-6 shows the percent these engines
contribute to the mobile source diesel PM_2.5 inventory in a
variety of urban areas in 2001 and 2030. In 2001, a number of
metropolitan areas saw locomotives and marine diesel engines contribute
a much larger share to their local inventories than the national
average including Houston (42 percent), Los Angeles (32 percent), and
Baltimore (23 percent). In 2030, each of these metropolitan areas would
continue to see locomotive and marine diesel engines comprise a larger
portion of their mobile source diesel PM_2.5 inventory than
the national average as would other communities including Cleveland (72
percent), Chicago (70 percent) and Chattanooga (70 percent).

Table II-6.--Locomotive and Marine Diesel Contribution to Mobile Source
Diesel PM2.5 Inventories in Selected Metropolitan Areas in 2001 and 2030
------------------------------------------------------------------------
2001 2030
Metropolitan area (MSA) Percent Percent
------------------------------------------------------------------------
National Average.................................. 18 65
Los Angeles, CA................................... 32 73
Houston, TX....................................... 42 85
Chicago, IL....................................... 25 70
Philadelphia, PA.................................. 20 64
Cleveland-Akron-Lorain, OH........................ 26 72
St. Louis, MO..................................... 22 68
Seattle, WA....................................... 17 61
Kansas City, MO................................... 21 68
Baltimore, MD..................................... 23 68
Cincinnati, OH.................................... 24 70
Boston, MA........................................ 8 41
Huntington-Ashland WV-KY-OH....................... 53 91
New York, NY...................................... 4 21
San Joaquin Valley, CA............................ 9 39
Minneapolis-St. Paul, MN.......................... 11 48
Atlanta, GA....................................... 6 30
Phoenix-Mesa, AZ.................................. 5 27
Birmingham, AL.................................... 17 58
Detroit, MI....................................... 5 26
Chattanooga, TN................................... 22 70
Indianapolis, IN.................................. 5 30
------------------------------------------------------------------------

(4) NO_X Emissions Reductions
In 2001 annual emissions from locomotive and marine diesel engines
totaled about 2.0 million tons. Table II-3 shows the distribution of
these NO_X emissions: locomotives contributed about 1.1
million tons, recreational marine diesel roughly 40,000 tons, and
commercial marine diesel (C1 and C2) 834,000 tons. Due to current
standards, annual NO_X emission from these engines drop to
1.6 million tons in 2030 with roughly proportional emission reductions
occurring in both the locomotive and commercial marine diesel
categories while the recreational marine diesel category experiences an
increase in PM_2.5 emissions. Both Table II-7 and Figure II-5
show NO_X

[[Page 15966]]

emissions remaining nearly flat through 2030 before beginning to rise
again due to growth in these sectors.
Table II-7 shows how the proposed rule would begin reducing
NO_X emissions from the current national inventory baseline
starting in 2015 when annual reductions of 84,000 tons would occur. By
2020 that number would grow to 293,000 tons of NO_X, by 2030
to 765,000 annual tons, and reductions would continue to grow through
2040 to about 1.1 million tons of NO_X annually.
These numbers are comparable to emission reductions projected in
2030 for our already established nonroad Tier 4 program. Table II-8
provides the 2030 NO_X emission reductions (and PM
reductions) for this proposed rule compared to the Heavy-Duty Highway
rule and Nonroad Tier 4 rule. The 2030 NO_X reductions of
about 740,000 tons for the Nonroad Tier 4 are similar to those from
this proposed rule.

Table II-7.--Locomotive and Marine Diesel NOX Emissions
[Short tons/year]
----------------------------------------------------------------------------------------------------------------
2015 2020 2030 2040
----------------------------------------------------------------------------------------------------------------
Without Proposed Rule................................... 1,633,000 1,582,000 1,582,000 1,703,000
With Proposed Rule...................................... 1,549,000 1,289,000 817,000 579,000
Reductions From Proposed Rule........................... 84,000 293,000 765,000 1,124,000
----------------------------------------------------------------------------------------------------------------

Table II-8.--Projected 2030 Emissions Reductions From Recent Mobile
Source Rules
[Short tons]
------------------------------------------------------------------------
Rule NOX PM2.5
------------------------------------------------------------------------
Proposed Locomotive and Marine.................... 765,000 28,000
Nonroad Tier 4.................................... 738,000 129,000
Heavy-Duty Highway................................ 2,600,000 109,000
------------------------------------------------------------------------

[GRAPHIC]
[TIFF OMITTED] TP03AP07.004

Although this proposed rule results in large nationwide
NO_X inventory reductions, it would also help urban areas
that have significant concentrations of locomotive and marine diesel
engines in their inventories. Table II-9 shows the percent these
engines contribute to the mobile source diesel NO_X inventory
in a variety of urban areas in 2001 and 2030. In 2001, a number of
metropolitan areas saw locomotives and marine diesel engines contribute
a much larger share to their local inventories than the national
average including Houston (32 percent), Kansas City (20 percent), and
Los Angeles (19 percent). In 2030, each of these metropolitan areas
would continue to see locomotive and marine diesel engines comprise a
larger portion of their mobile source diesel PM_2.5 inventory
than the national average as would other communities including
Birmingham (43 percent), Chicago (42 percent) and Chattanooga (40 percent).

[[Page 15967]]

Table II-9.--Locomotive and Marine Diesel Engine Contribution to Mobile
Source NOX Inventories in Selected Metropolitan Areas in 2001 and 2030
------------------------------------------------------------------------
2001 2030
Metropolitan areas (MSA) Percent Percent
------------------------------------------------------------------------
National Average.................................. 16 35
Los Angeles, CA................................... 19 38
Houston, TX....................................... 32 45
Chicago, IL....................................... 20 42
Philadelphia, PA.................................. 14 19
Cleveland-Akron-Lorain, OH........................ 19 40
New York, NY...................................... 5 8
St. Louis, MO..................................... 16 37
Seattle, WA....................................... 14 31
Kansas City, MO................................... 20 44
Cincinnati, OH.................................... 18 39
Huntington-Ashland, WV-KY-OH...................... 39 37
Boston, MA........................................ 7 11
San Joaquin Valley, CA............................ 9 26
Minneapolis-St. Paul, MN.......................... 9 20
Atlanta, GA....................................... 5 13
Birmingham, AL.................................... 17 43
Baltimore, MD..................................... 8 10
Phoenix-Mesa, AZ.................................. 6 15
Detroit, MI....................................... 3 9
Chattanooga, TN................................... 16 40
Indianapolis, IN.................................. 5 13
------------------------------------------------------------------------

(5) Volatile Organic Compounds Emissions Reductions
Emissions of volatile organic compounds (VOCs) from locomotive and
marine diesel engines based on a 50-state inventory are shown in Table
II-10, along with the estimates of the reductions in 2015, 2020, 2030
and 2040 we expect would result from the VOC exhaust emission standard
in our proposed rule. In 2015 15,000 tons of VOCs would be reduced and
by 2020 reductions would almost double to 27,000 tons annually from
these engines. Over the next ten years annual reductions from
controlled locomotive and marine diesel engines would produce annual
VOC reductions of 42,000 tons in 2030 and 54,000 tons in 2040.
Figure II-6 shows our estimate of VOC emissions between 2005 and
2040 both with and without the proposed standards of this rule. We
estimate that VOC emissions from locomotive and marine diesel engines
would be reduced by 60 percent by 2030 and by 70 percent in 2040.

Table II-10.--Locomotive and Marine Diesel VOC Emissions
[ short tons/year]
------------------------------------------------------------------------
2015 2020 2030 2040
------------------------------------------------------------------------
Without Proposed Rule....... 72,000 71,000 72,000 78,000
With Proposed Rule.......... 57,000 44,000 30,000 24,000
Reductions From Proposed 15,000 27,000 42,000 54,000
Rule.......................
------------------------------------------------------------------------

[GRAPHIC]
[TIFF OMITTED] TP03AP07.005

III. Emission Standards

This section details the emission standards, implementation dates,
and other major requirements of the proposed program. Following brief
summaries of the types of locomotives and marine engines covered and of
the existing standards, we describe the proposed provisions for setting:
? Tier 3 and Tier 4 standards for newly-built locomotives,
? Standards for remanufactured Tier 0, 1, and 2 locomotives,

[[Page 15968]]

? Standards and other provisions for diesel switch locomotives,
? Requirements to reduce idling locomotive emissions, as
well as possible ways to encourage emission reductions through the
optimization of multi-locomotive teams (consists), and
? Tier 3 and Tier 4 standards for newly-built marine diesel engines.
As discussed in sections I.A(2) and VII.A(2), we are also
soliciting comment on setting standards for remanufactured marine
diesel engines.
A detailed discussion of the technological feasibility of the
proposed standards follows the description of the proposed program. The
section concludes with a discussion of considerations and activities
surrounding emissions from large Category 3 engines used on ocean-going
vessels, although we are not proposing provisions for these engines in
this rulemaking.
To ensure that the benefits of the standards are realized in-use
and throughout the useful life of these engines, and to incorporate
lessons learned over the last few years from the existing test and
compliance program, we are also proposing revised test procedures and
related certification requirements. In addition, we are proposing to
continue the averaging, banking, and trading (ABT) emissions credits
provisions to demonstrate compliance with the standards. These
provisions are described further in section IV.

A. What Locomotives and Marine Engines Are Covered?

The regulations being proposed would affect locomotives currently
regulated under part 92 and marine diesel engines and vessels currently
regulated under parts 89 and 94, as described below.\97\
---------------------------------------------------------------------------

\97\ All of the regulatory parts referenced in this preamble are
parts in Title 40 of the Code of Federal Regulations, unless
otherwise noted.
---------------------------------------------------------------------------

With some exceptions, the regulations apply for all locomotives
that operate extensively within the United States. See section IV.B for
a discussion of the exemption for locomotives that are used only
incidentally within the U.S. The exceptions include historic steam-
powered locomotives and locomotives powered solely by an external
source of electricity. In addition, the regulations generally do not
apply to existing locomotives owned by railroads that are classified as
small businesses.\98\ Furthermore, engines used in locomotive-type
vehicles with less than 750 kW (1006 hp) total power (used primarily
for railway maintenance), engines used only for hotel power (for
passenger railcar equipment), and engines that are used in self-
propelled passenger-carrying railcars, are excluded from these
regulations. The engines used in these smaller locomotive-type vehicles
are generally subject to the nonroad engine requirements of Parts 89
and 1039.
---------------------------------------------------------------------------

\98\ This small business provision is limited to railroads that
are classified as small businesses by the Small Business
Administration (SBA). Many but not all Class II and III railroads
qualify as small businesses for this provision. See the 1998
locomotive rule (63 FR 18978, April 16, 1998) for a complete
discussion of the basis and application of this provision.
---------------------------------------------------------------------------

There are currently three tiers of locomotive emission standards.
The Tier 0 standards apply only to locomotives originally manufactured
before 2002, the Tier 1 standards apply to new locomotives manufactured
in 2002-2004, and the Tier 2 standards apply to new locomotives
manufactured in 2005 and later. Under the existing regulations, the
applicability of the Tier 1 and Tier 2 standards is based on the date
of manufacture of the locomotive, rather than the engine. Thus, a newly
manufactured engine in 2005 that is used to repower a 1990 model year
locomotive would be subject to the Tier 0 emission standards, which are
also applicable to all other 1990 model year locomotives. As described
in section IV.B, we are proposing some changes to this approach.
The marine diesel engines covered by this rule would include
propulsion engines used on vessels from recreational and small fishing
boats to super-yachts, tugs and Great Lakes freighters, and auxiliary
engines ranging from small gensets to large generators on ocean-going
vessels.\99\ Marine diesel engines are categorized both by per cylinder
displacement and by rated power. Consistent with our existing marine
diesel emission control program, the proposed standards would apply to
any marine diesel engine with per cylinder displacement below 30 liters
installed on a vessel flagged or registered in the United States.
According to our existing definitions, a marine engine is defined as an
engine that is installed or intended to be installed on a marine vessel.
---------------------------------------------------------------------------

\99\ Marine diesel engines at or above 30 l/cyl displacement are
not included in this program. See Section 3E, below.
---------------------------------------------------------------------------

While marine diesel engines up to 37 kW (50 hp) are currently
covered by our nonroad Tier 1 and Tier 2 standards, they were not
included in the nonroad Tier 3 and Tier 4 programs. Instead, they are
covered in this rule, making this a comprehensive control strategy for
all marine diesel engines below 30 liters per cylinder displacement.
This is a very broad range of engines and they are grouped into several
categories for the existing standards, as described in detail in
Chapter 1 of the draft RIA.
Consistent with our current marine diesel engine program, the
standards described in this proposal would apply to engines
manufactured for sale in the United States or imported into the United
States beginning with the effective date of the standards. Any engine
installed on a new vessel flagged or registered in the U.S. would be
required to meet the appropriate emission limits. Also consistent with
our current marine diesel engine program, the standards would also
apply to any engine installed for the first time in a marine vessel
flagged or registered in the U.S. after having been used in another
application subject to different emission standards. In other words, an
existing nonroad diesel engine would become a new marine diesel engine,
and subject to the marine diesel engine standards, when it is marinized
for use in a marine application.
Our current marine diesel engine emission controls do not apply to
marine diesel engines on foreign vessels entering U.S. ports. At this
time we believe it is appropriate to postpone consideration of the
application of our national standards to engines on foreign vessels to
a future rulemaking that would consider controls for Category 3 engines
on ocean-going vessels. This will allow us consider the engines on
foreign vessels as an integrated system, to better evaluate the
regulatory options available for controlling their overall emission
contribution to U.S. ambient air quality.
Nevertheless, we are soliciting comment on whether the emission
standards we are proposing in this action should apply to engines below
30 liters per cylinder displacement installed on foreign vessels
entering U.S. ports, and to no longer exclude these engines from the
emission standards under 40 CFR 94.1(b)(3). Commenters are also invited
to suggest when the standards should apply to foreign vessels. For
example, the standards could apply based on the date the engine is
built or, consistent with MARPOL Annex VI, the date the vessel is built.

B. Existing EPA Standards

NO_X emission levels from newly-built locomotives have
been reduced over the past several years from unregulated levels of
over 13 g/bhp-hr (17 g/kW-hr) to the current Tier 2 standard level for
newly-built locomotives of 5.5 g/bhp-hr

[[Page 15969]]

(7.3 g/kW-hr)--a 60 percent reduction.\100\ PM reductions on the order
of 50 percent have also been achieved under a Tier 2 standard level of
0.20 g/bhp-hr (0.27 g/kW-hr). EPA emission standards for marine diesel
engines vary somewhat due to the ranges in size and application of
engines included; however Tier 2 levels for recreational and commercial
marine engines are generally comparable in stringency to those adopted
for locomotives, and are now in the process of phasing in over 2004-
2009. See Chapter 1 of the draft RIA for a complete listing of the
existing standards, including standards for remanufactured locomotives.
---------------------------------------------------------------------------

\100\ Consistent with past EPA rulemakings, our regulations
generally express standards, power ratings, and other quantities in
international SI (metric) units--kW, g/kW-hr, etc. One exception to
this is Part 92 (locomotives), which for historical reasons
expresses standards in g/bhp-hr. This proposal retains these
established norms for locomotive and marine engine regulations.
However, in this preamble we have chosen to express standards in
units of g/bhp-hr, to provide a common frame of reference. Where
helpful for clarity, we have also included g/kW-hr standards in
parentheses. In any compliance questions that might arise from
differences in these due to, for example, rounding conventions, the
regulations themselves establish the applicable requirements.
---------------------------------------------------------------------------

The Tier 2 emissions reductions have been achieved largely through
engine calibration optimization and engine hardware design changes
(such as improved fuel injectors and turbochargers, increased injection
pressure, intake air after-cooling, combustion chamber design, reduced
oil consumption and injection timing) Although these reductions in
locomotive and marine emissions are important, they only bring today's
cleanest locomotives and marine diesels to roughly the emissions levels
of new trucks in the early 1990's, on the basis of grams per unit of
work done.

C. What Standards Are We Proposing?

(1) Locomotive Standards
(a) Line-Haul Locomotives
We are proposing new emission standards for newly-built and
remanufactured line-haul locomotives. Our proposed standards for newly-
built line-haul locomotives would be implemented in two tiers: First, a
new Tier 3 PM standard of 0.10 g/bhp-hr (0.13 g/kW-hr) taking effect in
2012, based on engine design improvements; second, new Tier 4 standards
of 0.03 g/bhp-hr (0.04 g/kW-hr) for PM, 0.14 g/bhp-hr (0.19 g/kW-hr)
for HC (both taking effect in 2015), and 1.3 g/bhp-hr (1.8 g/kW-hr) for
NO_X (taking effect in 2017), based on the application of the
high-efficiency catalytic aftertreatment technologies now being
developed and introduced in the highway diesel sector. Our proposed
standards for remanufactured line-haul locomotives would apply to all
Tier 0, 1, and 2 locomotives and are based on engine design
improvements. The feasibility of the proposed standards and the
technologies involved are discussed in detail in section III.D. Table
III-1 summarizes the proposed line-haul locomotive standards and
implementation dates. See section III.C(3) for a discussion of the HC
standards.

Table III-1.--Proposed Line-Haul Locomotive Standards
[g/bhp-hr]
----------------------------------------------------------------------------------------------------------------
Standards apply to: Date PM NOX HC
----------------------------------------------------------------------------------------------------------------
Remanufactured Tier 0 & 1.................... 2008 as Available, 2010 Required 0.22 \a\ 7.4 \a\ 0.55
Remanufactured Tier 2........................ 2008 as Available, 2013 Required 0.10 5.5 0.30
New Tier 3.................................. 2012............................ 0.10 5.5 0.30
New Tier 4................................... PM and HC 2015 NOX 2017......... 0.03 1.3 0.14
----------------------------------------------------------------------------------------------------------------
\a\ For Tier 0 locomotives originally manufactured without a separate loop intake air cooling system, these
standards are 8.0 and 1.00 for NOX and HC, respectively.

(i) Remanufactured Locomotive Standards
We have previously regulated remanufactured locomotive engines
under section 213(a)(5) of the Clean Air Act as new locomotive engines
and we propose to continue to do so in this rule. Under our proposed
standards, the existing fleet of locomotives that are currently subject
to Tier 0 standards (our current remanufactured engine standards) would
need to comply with a new Tier 0 PM standard of 0.22 g/bhp-hr (0.30 g/
kW-hr). They would also need to comply with a new Tier 0 NO_X
line-haul standard of 7.4 g/bhp-hr (9.9 g/kW-hr), except that Tier 0
locomotives that were built without a separate coolant loop for intake
air (that is, using engine coolant for this purpose) would be subject
to a less stringent Tier 0 NO_X standard of 8.0 g/bhp-hr
(10.7 g/kW-hr) on the line-haul cycle.
These non-separate loop locomotives were generally built before
1993, though some are of more recent model years. Because of their age,
many of them are likely to be retired and not remanufactured again, and
many are entering lower use applications within the railroad industry.
Correspondingly, their contribution to the locomotive emissions
inventory is diminishing. Our analysis indicates that it is feasible to
obtain a NO_X reduction for them on the order of 15 percent,
from the current Tier 0 line-haul NO_X standard of 9.5 g/bhp-
hr to the proposed 8.0 g/bhp-hr standard. However, we expect that any
further reduction would require the addition of a separate intake air
coolant loop, which provides more efficient cooling and therefore lower
NO_X. This would be a fairly expensive hardware change and
could have sizeable impacts on the locomotive platform layout and
weight constraints. We are aware that this group of older, non-separate
loop Tier 0 locomotives is fairly diverse, and that achieving even a
8.0 g/bhp-hr NO_X standard along with a stringent Tier 0 PM
standard will be more difficult on some of these models than on others.
We request comment on whether there are any locomotive families within
this group for which meeting the proposed 8.0 g/bhp-hr standard may not
be feasible, especially considering the cost of doing so and the age of
the locomotives involved. Commenters should discuss feasibility and
projected costs, and should also discuss the extent to which this
concern is mitigated by the prospect that these locomotives will be
retired rather than remanufactured anyway, or will be moved to lower
usage switcher or small railroad applications, and therefore will be
less likely to be remanufactured under the new Tier 0 standards.
We propose to apply the new Tier 0 standards (and corresponding
switch-cycle standards) when the locomotive is remanufactured on or
after January 1, 2008. However, if no certified emissions

[[Page 15970]]

control system exists for the locomotive before October 31, 2007, these
standards will instead apply 3 months after such a system is certified,
but no later than January 1, 2010. This would provide an incentive to
develop and certify systems complying with these standards as early as
possible, but allow the railroad to avoid having to delay planned
rebuilds if a certified system is not available when the program is
expected to begin in 2008. We also propose to include a reasonable cost
provision, described in section IV.B, to protect against the unlikely
event that the only certified systems made available when this program
starts in 2008 will be exorbitantly priced.
Although under this approach, certification of new remanufacture
systems before 2010 is voluntary, we believe that developers would
strive to certify systems to the new standards as early as possible,
even in 2008, to establish these products in the market, especially for
the higher volume locomotive models anticipated to have significant
numbers coming due for remanufacture in the next few years. This focus
on higher volume products also maximizes the potential for large
emission reductions very early in this program, greatly offsetting the
effect of slow turnover to new Tier 3 and Tier 4 locomotives inherent
in this sector.
We are also proposing to set new more stringent standards for
locomotives currently subject to Tier 1 and Tier 2 standards, to apply
at the point of next remanufacture after the proposed implementation
dates. Tier 1 locomotives would need to comply with the same new PM
standard of 0.22 g/bhp-hr (0.30 g/kW-hr) required of Tier 0 locomotives
(they are already subject to the 7.4 g/bhp-hr (9.9 g/kW-hr)
NO_X standard). This in essence expands the model years
covered by the Tier 1 standards from 2002-2004 to roughly 1993-2004,
greatly increasing the size of the Tier 1 fleet while at the same time
reducing emissions from this broadened fleet. Under the proposal, Tier
2 locomotives on the rails today or built prior to the start of Tier 3
would need to comply with a new Tier 2 PM line-haul standard of 0.10 g/
bhp-hr (0.13 g/kW-hr). Because this is equal to the Tier 3 standard, it
essentially adds the entire fleet of Tier 2 locomotives to the clean
Tier 3 category over a period of just a few years, as they go through a
remanufacture cycle.
The implementation schedule for the new Tier 1 standard would be
the same as the 2008/2010 schedule discussed above for Tier 0
locomotives. Meeting the new Tier 2 standard would be required somewhat
later, in 2013, reflecting the additional redesign challenge involved
in meeting this more stringent standard, and the need to spread the
redesign and certification workload faced by the manufacturers overall.
However, as for Tier 0 and Tier 1 locomotives, we are proposing that if
a certified Tier 2 remanufacture system meeting the new standard is
available early, anytime after January 1, 2008, this system would be
required to be used, starting 3 months after it is certified, subject
to a reasonable cost provision as with early Tier 0 and Tier 1
remanufactures. We request comment on whether use of certified Tier 2
remanufacture systems should be required on the same schedule as Tier
3, that is, starting in 2012, given that we expect the upgraded Tier 2
designs to be very similar to newly-built Tier 3 designs, and the
likelihood that substantial numbers of Tier 2 locomotives may be
approaching their first scheduled remanufacture by 2012.
These proposed remanufactured locomotive standards represent PM
reductions of about 50 percent, and (for Tier 0 locomotives with
separate loop intake air cooling) NO_X reductions of about 20
percent. Significantly, these reductions would be substantial in the
early years. This would be important to State Implementation Plans
(SIPs) being developed to achieve attainment with national ambient air
quality standards (NAAQS), owing to the 2008 start date and relatively
rapid remanufacture schedule (roughly every 7 years, though it varies
by locomotive model and age).
(ii) Newly-Built Locomotive Standards
We are requesting comment on whether additional NO_X
emission reductions would be feasible and appropriate for Tier 3
locomotives in the 2012 timeframe. There are proven diesel technologies
not currently employed in Tier 2 locomotives that can significantly
reduce NO_X emissions, most notably cooled exhaust gas
recirculation (EGR). Although employed successfully in the heavy-duty
highway diesel sector since 2003, a considerable development and
redesign program would need to be undertaken by locomotive
manufacturers to apply cooled EGR to Tier 3 locomotives. This
development work would not be limited to the engine but would include
substantial changes to the locomotive chassis to handle the higher
levels of heat rejection (engine cooling demand) required for cooled
EGR. We project that it would require a similar degree of engineering
time and effort to develop a cooled EGR solution for locomotive diesel
engines as it will to develop the urea SCR based solution upon which we
are basing our proposed Tier 4 NO_X standard. Therefore, we
have not considered the application of cooled EGR in setting our
proposed Tier 3 standard.
It may be possible to reoptimize existing Tier 2 NO_X
control technologies, most notably injection timing retard (used to
some degree on all diesel locomotives), to achieve a more modest
NO_X reduction of 10 to 20 percent from the current Tier 2
levels. In fact, a version of General Electric's Tier 2 locomotive is
available today that achieves such NO_X reductions for
special applications such as the California South Coast Locomotive
Fleet Average Emissions Program. In general, the use of injection
timing retard to control NO_X emissions comes with a tradeoff
against fuel economy, durability and increased maintenance depending
upon the degree to which injection timing retard is applied. Experience
with on-highway trucks suggests that a 20 percent NO_X
reduction based solely on injection timing retard could result in an
increase of fuel consumption as much as 5 percent. We request comment
on the feasibility and other impacts of applying technologies such as
these in the Tier 3 timeframe. We also request comment on the extent to
which any workload-based impediments to applying such technologies in
Tier 3 could be addressed via balancing it by obtaining less than the
proposed NO_X reductions from remanufactured locomotives. We
believe that a Tier 3 NO_X standard below 5 g/bhp-hr might be
achievable with a limited impact if additional engineering resources
were invested to optimize such a system for general line-haul
application. We encourage commenters supporting lower NO_X
levels for Tier 3 locomotives to address whether some tradeoff in
engineering development (or emissions averaging) between new Tier 3
locomotives and remanufactured Tier 0 locomotives might be appropriate.
For example, would it be appropriate to set a Tier 3 NO_X
standard at 4.5 g/bhp-hr, but relax the NO_X standard for
later model Tier 0 locomotives to 8.0 g/bhp-hr instead of 7.4 g/bhp-hr?
We are proposing that a manufacturer may defer meeting the Tier 4
NO_X standard until 2017. However, we expect that each
manufacturer will undertake a single comprehensive redesign program for
Tier 4, using this allowed deferral to work through any implementation
and technology prove-out issues that might arise with advanced
NO_X control technology, but relying on the same basic
locomotive platform and overall emission control space allocations for
all Tier 4 product years. For this reason we are proposing

[[Page 15971]]

that locomotives certified under Tier 4 in 2015 and 2016 without Tier 4
NO_X control systems have this system added when they undergo
their first remanufacture, and be subject to the Tier 4 NO_X
standard thereafter.
We are proposing that, starting in Tier 4, line-haul locomotives
will not be required to meet standards on the switch cycle. Line-haul
locomotives were originally made subject to switch cycle standards to
help ensure robust control in use and in recognition of the fact that
many line haul locomotives have in the past been used for switcher
service later in life. As explained in section III.C(1)(b), the latter
is of less concern today. Also, we expect that the aftertreatment
technologies used in Tier 4 will provide effective control over a broad
range of operation, thus lessening the need for a switch cycle to
ensure robust control. We propose that newly-built Tier 3 locomotives
and Tier 0 through Tier 2 locomotives remanufactured under this program
be subject to switch cycle standards, set at levels above the line-haul
cycle standards (Table III-1) in the same proportion that the original
Tier 0 through Tier 2 switch cycle standards are above their corresponding
line-haul cycle standards. See section III.C(1)(b) for details.
(b) Switch Locomotives
Our 1998 locomotive rule included some provisions aimed at
addressing emissions from switch locomotives. We adopted a set of
switcher standards and a switcher test cycle. This cycle made use of
the same notch-by-notch test data as the line haul cycle, but
reweighted these notch-specific emission results to correspond to
typical switcher duty. In addition to controlling emissions from
dedicated switchers, we viewed this cycle as adding robustness to the
line-haul emissions control program. For this reason, and because aging
line-haul locomotives have often in the past found utility as
switchers, we subjected all regulated locomotives to the switch cycle.
We also allowed for dedicated switch locomotives, defined as
locomotives designed or used primarily for short distance operation and
using an engine with rated power at 2300 hp (1700 kW) or less, to be
optionally exempted from the line-haul cycle standards.
There have been a number of changes in the rail industry since our
1998 rulemaking that are relevant to switchers. First, locomotives
marketed for line-haul service have continued to increase in size, to a
point where today's 4000+hp (3000+kW) line-haul locomotives are too
large for practical use in switching service. Second, there have been
practically no U.S. sales of newly-built switchers by the primary
locomotive builders, EMD and GE, for many years. Third, smaller
builders have entered this market, selling new or refurbished
locomotives with one to three newly-built diesel engines originally
designed for the nonroad equipment market, but recertified under Part
92, or sold under the 40 CFR 92.907 provisions that allow limited sales
of locomotives using nonroad-certified engines. Fourth, although this
new generation of switchers has shown great promise, their purchase
prices on the order of a million dollars or more, compared to the
relatively low cost of maintaining old switchers, have limited sales
primarily for use in California and Texas where state government
subsidies are available.
All of these factors together have produced a situation in which
the current fleet of old switchers, including many pre-1973 locomotives
not subject to any emissions standards, is maintained and kept in
service. Because they have relatively light duty cycles and generally
operate very close to repair facilities, they can be maintained almost
indefinitely. Though many have poor fuel economy, this alone is not of
great enough concern to the railroads to warrant replacing them because
even very busy switchers consume a fraction of the fuel used by long-
distance line-haul locomotives.
At the same time, these older switch locomotives have come under
increasing public scrutiny. When operated in railyards located in urban
neighborhoods, they have often become the focus of complaints from
citizens groups about noise, smoke, and other emissions, and state and
local governments have begun to place a higher priority on reducing
their emissions.\101\
---------------------------------------------------------------------------

\101\ See, for example, letter from Catherine Witherspoon,
Executive Director of the California Air Resources Board, to EPA
Administrator Stephen Johnson, September 7, 2006.
---------------------------------------------------------------------------

We note that switchers (or any other locomotives) that have not
been remanufactured to EPA standards are not considered covered by the
full preemption of state and local emission standards in section
209(e)(1) of the Clean Air Act, which applies to standards relating to
the control of emissions from new locomotive engines. Similarly, the
preemption that does apply for locomotives that are certified to EPA
standards does not generally apply for any locomotive that has
significantly exceeded its useful life. The provisions of section
209(e)(2) pertaining to other nonroad engines would apply for such
engines, as well as other engines used in locomotives excluded from the
definition of ``new.'' Such engines may be subject to regulation by
California and other states.
As discussed in section II.B, we too are concerned that emissions
from locomotives in urban railyards, many of which are switch
locomotives, are causing substantial adverse health effects. Some
railroads have been attempting to address these concerns, adopting
voluntary idling restrictions and, where government subsidies are
available, replacing older switchers with cleaner, quieter new-
generation switchers. In light of these trends and market realities, we
believe it is appropriate to propose standards and other provisions
specific to switch locomotives, aimed at obtaining substantial overall
emission reductions from this important fleet of locomotives.
We are proposing Tier 3 and 4 emission standards for newly-built
switch locomotives, shown in Table III-2, based on the capability of
the Tier 3 and 4 nonroad engines that will be available to power switch
locomotives in the future under our clean nonroad diesel program. We
propose to retain the existing switch locomotive test cycle upon which
compliance with these standards would be measured, but not to apply the
line-haul standards and cycle to Tier 3 and 4 switchers, in light of
the divergence that has occurred in the design of newly-built switch
and line-haul locomotives. We also propose that Tier 0, 1, and 2 switch
locomotives certified only on the switch cycle (as allowed in our Part
92 regulations), be subject to a set of remanufactured locomotive
standards equivalent to our proposed program for remanufactured line-
haul locomotives, with proportional levels of emission reductions.
These standards are also the switch cycle standards for the Tier 3 and
earlier line-haul locomotives that are subject to compliance
requirements on the switch cycle. In the case of the Tier 3 line-haul
locomotives, we are proposing that the Tier 2 switch cycle standards be
applied rather than the Tier 3 standards for dedicated switchers
because the latter are based on nonroad engines.

[[Page 15972]]

Table III-2.--Proposed Emission Standards for Switch Locomotives
[g/bhp-hr]
----------------------------------------------------------------------------------------------------------------
Switch locomotive standards
apply to: PM NOX HC Date
----------------------------------------------------------------------------------------------------------------
Remanufactured Tier 0.......... 0.26 11.8 2.10 2008 as available, 2010 required.
Remanufactured Tier 1.......... 0.26 11.0 1.20 2008 as available, 2010 required.
Remanufactured Tier 2.......... 0.13 8.1 0.60 2008 as available, 2013 required.
Tier 3......................... 0.10 5.0 0.60 2011.
Tier 4......................... 0.03 1.3 0.14 2015.
----------------------------------------------------------------------------------------------------------------

Standards and implementation dates for large nonroad engines vary
by horsepower and by whether or not the engine is designed for portable
electric power generation (gensets), as shown in Table III-3. This is
significant for the switch locomotive program because it has been the
practice for switch locomotive builders to use a variety of nonroad
engine configurations. For example, a manufacturer building a 2100 hp
switcher using nonroad engines in 2011 could team three 700 hp engines
designed to the nonroad Tier 4 standards of 0.01 g/bhp-hr PM and 0.30
g/bhp-hr NO_X, or two 1050 hp engines at 0.075/2.6 g/bhp-hr
PM/NO_X, or a single 2100 hp engine at 0.075/0.50 or 0.075/
2.6 g/bhp-hr PM/NO_X, depending on if the engine is a genset
engine or not.
As discussed in the nonroad Tier 4 rulemaking in which we set these
standards, we believe that the standards set for all of these nonroad
engines achieve the greatest degree of emission reduction achievable
through the application of technology which the Administrator
determines will be available, with appropriate consideration to factors
listed in the Clean Air Act. There are reasons for a switcher
manufacturer to choose one configuration of engines over another
related to function, packaging, reliability and other factors. We
believe that limiting a manufacturer's choice to only the cleanest
configuration in any given year would hinder optimum designs and
thereby would tend to work against our goal of encouraging the turnover
of the current fleet of old switchers. Furthermore, we note that there
is no single large engine category that consistently has the most
stringent nonroad Tier 4 PM and NO_X standards from year to
year. We also note that, because State subsidies for the purchase of
new switch locomotives have been clearly tied to their lower emissions,
and also because the use of lower-emitting engines can generate
valuable ABT credits, there is likely to be continuing pressure driving
the industry toward the cleanest nonroad engines available in whatever
new switcher market does develop.

Table III-3.--Large Nonroad Engine Tier 4 Standards
[g/bhp-hr]
----------------------------------------------------------------------------------------------------------------
Rated power PM NOX Model year
----------------------------------------------------------------------------------------------------------------
[lE]750 hp....................................................... 0.01 \a\ 3.0 (NOX+NMHC) 2011
0.01 0.30 2014
750-1200 hp...................................................... 0.075 2.6 2011
0.02 \b\ 0.50 2015
>1200 hp......................................................... 0.075 \b\ 0.50 2011
0.02 \b\ 0.50 2015
----------------------------------------------------------------------------------------------------------------
a 0.30 NOX for 50% of sales in 2011-2013, or alternatively 1.5 g NOX for 100% of sales.
b 2.6 for non-genset engines--setting the long-term Tier 4 standard for these engines was deferred in the
Nonroad Tier 4 Rule.

There is one exception to this approach that we consider necessary.
In the Tier 4 nonroad engine rule, we deferred setting a final Tier 4
NO_X standard for non-genset engines over 750 hp. These are
typically used in large bulldozers and mine haul trucks. This was done
in order to allow additional time to evaluate the technical issues
involved in adapting NO_X control technology to these
applications and engines (69 FR 38979, June 29, 2004). We believe it is
appropriate to propose a Tier 4 NO_X standard for switch
locomotives in 2015 based on SCR technology, as we are proposing for
line-haul locomotives in 2017. We believe this to be feasible because
the switch locomotive designer will have a variety of nonroad engine
choices equipped with SCR available in 2015, such as multiple < 750 hp
engines or larger genset engines, an opportunity that is not available
to large nonroad machine designers due to functional and packaging
constraints. To set a non-SCR based standard for switch locomotives
indefinitely, or to wait to do so after we set the final Tier 4
NO_X standard for mobile machine engines above 750 hp, would
create significant uncertainty for the manufacturers and railroads, and
would be contrary to our intent to reduce locomotive emissions in
switchyards. We note too that SCR introduction in the fairly limited
fleet of newly-built switchers likely to exist in 2015 and 2016
provides an opportunity for railroads to become familiar with urea
handling and SCR operation in accessible switchyards, before large
scale introduction in the far-ranging line-haul fleet.
Although we are factoring the current practice of building new
switchers powered by nonroad-certified engines into the design of the
program, it is not our intent to discourage the development and sale of
traditional medium-speed engine switch locomotives. We have evaluated
the proposed Tier 3 and 4 standards in this context and have concluded
that they will be feasible for switchers using medium-speed engines as
well as higher-speed nonroad engines.
Because in today's market the certifying switch locomotive
manufacturer is typically a purchaser of nonroad engines and not
involved in their design, we see the value in providing a streamlined
option to help in the early implementation of this program. As
described in Section IV, we are proposing that, for a program start-

[[Page 15973]]

up period sufficient to encourage the turnover of the existing switcher
fleet to the new cleaner engines, switch locomotives may use nonroad-
certified engines without need for certification under the locomotive
program. Because of large differences in how the locomotive and nonroad
programs operate in such areas as useful life and in-use testing, we do
not believe it appropriate to allow locomotive ABT credits to be
generated or used by locomotives sold under this option, though of
course this would not preclude nonroad engine ABT credits under that
program. For the same reasons, we also think it makes sense to
eventually sunset this option after it has served its purpose of
encouraging the early introduction of new low-emitting switch
locomotives. We propose that the streamlined path be available for 10
years, through 2017, and ask for comment on whether a shorter or longer
interval is appropriate, taking into account the turnover incentive
provisions described below. We are proposing other compliance and ABT
provisions relevant to switch locomotives as discussed in section
IV.B(1), (2), (3), and (9).
Finally, we are proposing a rewording of the definition of a switch
locomotive to make clear that it is the total switch locomotive power
rating that must be below 2300 hp to qualify, not the engine power
rating, and to drop the unnecessary stipulation that it be designed or
used primarily for short distance operation. This clears up the
ambiguity in the current definition over multi-engine switchers.
(c) Reduction of Locomotive Idling Emissions
Even in very efficient railroad operations, locomotive engines
spend a substantial amount of time idling, during which they emit
harmful pollutants, consume fuel, create noise, and increase
maintenance costs. A significant portion of this idling occurs in
railyards, as railcars and locomotives are transferred to build up
trains. Many of these railyards are in urban neighborhoods, close to
where people live, work, and go to school.
Short periods of idling are sometimes unavoidable, such as while
waiting on a siding for another train to pass. Longer periods of idling
operation may be necessary to run accessories such as cab heaters/air
conditioners or to keep engine coolant (generally water without anti-
freeze to maximize cooling efficiency) from freezing and damaging the
engine if an auxiliary source of heat or power is not installed on the
locomotive. Locomotive idling may also occur due to engineer habits of
not shutting down the engine, and the associated difficulty in
determining just when the engine can be safely shut down and for how long.
Automatic engine stop/start (AESS) systems have been developed to
start or stop a locomotive engine based on parameters such as: ambient
temperature, battery charge, water and oil temperature, and brake
system pressure. AESS systems have been proven to reliably and safely
reduce unnecessary idling. Typically they will shutdown the locomotive
after a specified period of idling (typically 15-30 minutes) as long as
the parameters are all within their required specifications. If one of
the aforementioned parameters goes out of its specified range, the AESS
will restart the locomotive and allow it to idle until the parameters
have returned to their required limits. Although developed primarily to
save fuel, AESS systems also reduce idling emissions and noise by
reducing idling time. Any emissions spike from engine startup has been
found to be minor, and thus idle emissions are reduced in proportion to
idling time eliminated. It is expected that overall PM and
NO_X idling emission reductions of up to 50 percent can be
achieved through the use of AESS.
A further reduction in idling emissions can be achieved through the
use of onboard auxiliary power units (APUs), either as standalone
systems or in conjunction with an AESS. There are two main
manufacturers of APUs, EcoTrans which manufacturers the K9 APU, and Kim
Hotstart which manufactures the Diesel Driven Heating System (DDHS). In
contrast to AESS, which works to reduce unnecessary idling, the APU
goes further by also reducing the amount of time when locomotive engine
idling is necessary, especially in cold weather climates. APUs are
small (less than 50 hp) diesel engines that stop and start themselves
as needed to provide heat to both the engine coolant and engine oil,
power to charge the batteries and to run necessary accessories such as
those required for cab comfort. This allows the much larger locomotive
engine to be shut down while the locomotive remains in a state of
readiness thereby reducing fuel consumption without the risk of the
engine being damaged in cold weather. If an APU does not have the
capability of an AESS built in, it may need to be installed in
conjunction with one in order to receive the full complement of idle
reductions that the combination of technologies can provide. The APUs
are nonroad engines compliant with EPA or State of California nonroad
engine standards, and emit at much lower levels than an idling locomotive.
Installation of an APU today costs approximately $25,000 to
$35,000; while an AESS can cost anywhere from $7,500 to $15,000.\102\
The costs vary depending on the model and configuration of the
locomotive on which the equipment is being installed, and would likely
be substantially lower if incorporated into the design of a newly-built
locomotive. The amount of idle reduction each system can provide is
also dependent on a number of variables, such as what the function of
the locomotive is (e.g. a switcher or a line-haul), where it operates
(i.e. geographical area), and what its operating characteristics are
(e.g. number of hours per day it operates). The duty cycles in 40 CFR
92.132, based on real world data available at the time they were
adopted in 1998, indicate a line haul locomotive idles nearly 40% of
its operating time, and a switcher locomotive idles nearly 60% of its
operating time. This idling time can be further divided into low idle
(when there is no load on the engine) and normal idle (when there is a
load on the engine). Only low idle can be reduced by an AESS, while an
APU can reduce normal idle (or idle in a higher notch such as notch 3
which can burn up to 11 gallons per hour). Another difference between
the two types of idle is the fuel consumption rate which is less at low
idle than normal idle (2.4-3.6 gallons per hour vs. 2.9-5.4 gallons per
hour, based on Tier 2 certification data).
---------------------------------------------------------------------------

\102\ Jessica Montanez and Matthew Mahler, ``Reducing Idling
Locomotives Emissions'', NC Department of Environment and Natural
Resources, DAQ http://daq.state.nc.us/planning/locoindex.shtml.

---------------------------------------------------------------------------

Although there is a gradual trend in the railroad industry toward
wider use of these types of idle control devices, we believe it is
important for ensuring air quality benefits to propose that idle
controls be required as part of a certified emission control system. We
are proposing that at least an AESS system be required on all new Tier
3 and Tier 4 locomotives, and also installed on all existing
locomotives that are subject to the new remanufactured engine
standards, at the point of first remanufacture under the new standards,
unless the locomotive is already equipped with idle controls.
Specifically, we are requiring that locomotives equipped with an AESS
device under this program must shut down the locomotive engine after no
more than 30 continuous minutes of idling, and be able to stop and
start the engine at least six times per day without

[[Page 15974]]

causing engine damage or other serious problems. The system must
prevent the locomotive engine from being restarted to resume extended
idling unless one of the following conditions necessitates such idling:
to prevent engine damage such as damage caused by coolant freezing, to
maintain air brake pressure, to perform necessary maintenance, or to
otherwise comply with applicable government regulations. EPA approval
of alternative criteria could be requested provided comparable idle
emissions reduction is achieved.
As described in the RIA, it is widely accepted that for most
locomotives, the fuel savings that result in the first several years
after installation of an AESS system will more than offset the cost of
adding the system to the locomotive. Given these short payback times
for adding idle reduction technologies to a typical locomotive, normal
market forces have led the major railroads to retrofit many of their
locomotives with such controls. However, as is common with pollution,
market forces generally do not account for the external social costs of
the idling emissions. This proposal addresses those locomotives for
which the railroads determine that the fuel savings are insufficient to
justify the cost of the retrofit. We believe that applying AESS to
these locomotives is appropriate when one also considers the very
significant emissions reductions that would result, as well as the
longer term fuel savings. We request comment on the need for this
requirement. We also request comment regarding the reasons why a
railroad might choose not to apply AESS absent this provision. Are
there costs for AESS and retrofits that are higher than our analysis
would suggest? Are there other reasons that would lead a railroad to
not adopt AESS universally?
Even though we are proposing to require only AESS systems, we
encourage the additional use of APUs by providing in our proposed test
regulations a way for the manufacturer to appropriately account for the
emission benefits of greater idle reduction. See Section IV.B(8) for
further discussion. We are not proposing that APUs must be installed on
every locomotive because it is not clear how much additional benefit
they would provide outside of regions and times of the year where low
temperatures or other factors that warrant the use of an APU exist, and
they do involve some inherent design and operational complexities that
could not be justified without commensurate benefits. We are however
asking for comment on requiring that some subset of new locomotives be
equipped with APUs where feasible and beneficial. We are also asking
for comments on whether to adopt a regulatory provision that would
exempt a railroad from AESS and/or APU requirements if it demonstrated
that it was achieving an equal or greater degree of idle reduction
using some other method.
(d) Load Control in a Locomotive Consist
A locomotive consist is the linking of two or more locomotives in a
train, typically where the lead locomotive has control over the power
and dynamic brake settings on the trailing locomotives. For situations
where locomotives are operated in a consist, EPA is requesting comment
on how the engine loads could be managed in a way which reduces the
combined emissions of the consist, and in what way our program can be
set up to encourage such reductions. Consists are commonly used in long
trains to achieve the power and traction levels necessary to move,
stop, and control the train. The trailing locomotives can be directly-
coupled to the lead locomotive, or, they may be placed anywhere along
the train and controlled remotely by the lead. The load settings of the
individual locomotives that make up a consist are not always equal--for
example, if the train has crested a hill, the leading locomotive(s)
could be operating under dynamic brake (to control the speed of the
train) while the trailing locomotives could be producing propulsion
power (to reduce strain on the couplers). Depending on the load, track,
terrain, and weather conditions, it is conceivable that the engine
loads of a consist could be managed to provide the lowest fuel
consumption for the power/traction needed. For example, the train power
can be distributed so that the lead engine is operating at its optimum
brake-specific fuel consumption point while trailing engines are
operated at reduced power settings and/or shut down. The capability to
manage and distribute engine power in a locomotive consist is available
on the market today.
We have been made aware that it may be possible to optimize the
configuration of locomotives in a consist for emissions performance
without compromising other key goals such as fuel economy and safety.
Our proposed regulations do not explicitly take such possible
optimization into account. However, if commenters believe that
significant emission reductions can be attained by controlling the
engine loads in a consist (beyond those attained by the current
practice of operating the consist to achieve the lowest fuel
consumption rate), we would solicit their views on how to calculate the
emissions reduction and on how the in-use operation of the consist
could be logged and reported. For example, it may be appropriate to
allow a manufacturer to use alternative notch weightings tailored to
operation in an emissions-optimized consist in demonstrating compliance
with the emissions standards, thus providing added flexibility in
designing such locomotives to meet the standards.
(2) Marine Standards
We are also proposing new emissions standards for newly-built
marine diesel engines with displacements under 30 liters per cylinder,
including those used in commercial, recreational, and auxiliary power
applications. As for locomotives, our ANPRM described a one-step marine
diesel program that would bring about the introduction of high-
efficiency exhaust aftertreatment in this sector. Just as for
locomotives, our analyses of the technical issues related to the
application of aftertreatment technologies to marine engines, informed
by our many discussions with stakeholders, have resulted in a proposal
for new standards in multiple steps, focused especially on the engines
with the greatest potential for large PM and NO_X emission
reductions. Our technical analyses are summarized in section III.D and
are detailed in the draft RIA.
In contrast to the locomotive sector, the marine diesel sector
covered by this rule is quite diverse. Commercial propulsion
applications range from small fishing boats to Great Lakes freighters.
Recreational propulsion applications range from sailboats to super-
yachts. Similarly, auxiliary power applications range from small
gensets, to generators used on barges, to large power-generating units
used on ocean-going vessels. Many of the propulsion engines are used to
propel high-speed planing boats, both commercial and recreational,
where low weight and high power density are critically important. Some
engines are situated in crowded engine compartments accessed through a
hatch in the deck, while others occupy relatively spacious engine
rooms. All of them share a high premium on reliability, considering the
potentially serious ramifications of engine failure while underway.
The resulting diversity in engine design characteristics is
correspondingly large. Sizes range from a few horsepower to thousands
of horsepower. Historically, we have categorized marine engines for
standards-setting purposes based on

[[Page 15975]]

cylinder displacements: C1 engines of less than 5 liters/cylinder, C2
from 5 to 30 liters/cylinder, and Category 3 (C3) at greater than 30
liters/cylinder. (These C3 engines typically power ocean-crossing ships
and burn residual fuel; we are not including such engines in this
proposal). Our past standard-setting efforts have found it helpful to
make further distinctions as well, considering small (less than 37 kW
(50 hp)) engines and C1 recreational engines as separate categories.
Recreational engines typically power recreational vessels designed
primarily for speed, and this imposes certain constraints on the type
of engine they can use. For a marine vessel to reach high speeds, it is
necessary to reduce the surface contact between the vessel and the
water, and consequently these vessels typically operate in a planing
mode. Planing imposes important design requirements, calling for low
vessel weight and short periods of very high power-- and thus prompting
a need for high power density engines. The tradeoff is less durability,
and recreational engines are correspondingly warranted for fewer hours
of operation than commercial marine engines. These special
characteristics are represented in EPA duty-cycle and useful life
provisions for recreational marine engines.
Unlike the locomotive sector, the vast majority of marine diesel
engines are derivatives of land-based nonroad diesel engines. Marine
diesel engine sales are significantly lower (by 10 or even 100 fold)
than the sales of the land-based nonroad engines from which they are
derived. For this reason, changes to marine engine technology typically
follow the changes made to the parent nonroad engine. For example, it
may be economically infeasible to develop and introduce a new fuel
system for a marine diesel engine with sales of 100 units annually,
while being desirable to do so for a land-based nonroad diesel engine
with sales of 10,000 or more units annually. Further, having developed
a new technology for land-based diesel engines, it is often cheaper to
simply apply the new technology to the marine diesel engine rather than
continuing to carry a second set of engine parts within a manufacturing
system for a marginal number of additional sales. Recognizing this
reality, our proposed marine standards are phased in to follow the
introduction of similar engine technology standards from our Nonroad
Tier 4 emissions program. In most cases, the corresponding marine diesel
standards will follow the Nonroad Tier 4 standards by one to two years.
We are proposing to retain the per-cylinder displacement approach
to establishing cutpoints for standards, but are revising and refining
it in several places to ensure that the appropriate standards apply to
every group of engines in this very diverse sector, and to provide for
an orderly phase-in of the program to spread out the redesign workload
burden:
(1) We are proposing to move the C1/C2 cutpoint from 5 liters/
cylinder to 7 liters/cylinder, because the latter is a more accurate
cutpoint between today's high- and medium-speed diesels (in terms of
revolutions per minute (rpm)), with their correspondingly different
emissions characteristics.
(2) We also propose to revise the per-cylinder displacement
cutpoints within Category 1 to better refine the application of standards.
(3) An additional differentiation is proposed between high power
density engines typically used in planing vessels and standard power
density engines, with a cutpoint between them set at 35 kW/liter (47
hp/liter). In addition to recreational vessels, the high power-density
engines are used in some commercial vessels, including certain kinds of
crew boats, research vessels, and fishing vessels. Unlike most
commercial vessels, these vessels are built for higher speed, which
allows them to reach research fields, oil platforms, or fishing beds
more quickly. This proposal addresses the technical challenges related
to reducing emissions from engines with high power density.
(4) In the past, we did not formally include marine diesels under
37 kW (50 hp) in Category 1, but regulated them separately as part of
the nonroad engine program, referring to them elsewhere as ``small
marine engines''. They are typically marinized land-based nonroad
diesel engines. Because we are now proposing to include these engines
in the current marine diesel rulemaking, this distinction is no longer
needed and so we are including these engines in Category 1 for Tier 3
and Tier 4 standards.
(5) Finally, we would further group engines by total rated power,
especially in regard to setting appropriate long-term aftertreatment-
based standards.
Note that we are retaining the differentiation between recreational
and non-recreational marine engines within Category 1 because there are
differences in the proposed standards for them.
Although this carefully targeted approach to standards-setting
results in a somewhat complicated array of emissions standards, we
believe it is justified because it maximizes overall emission
reductions by ensuring the most stringent standards feasible for a
given group of marine engines, and it also helps engine and vessel
designers to implement the program in the most cost effective manner.
The proposed standards and implementation schedules are shown on Tables
III-4-7.
Briefly summarized, the proposed marine diesel standards include
stringent engine-based Tier 3 standards, phasing in over 2009-2014. In
addition, the proposed standards include aftertreatment-based Tier 4
standards for engines at or above 600 kW (800 hp), phasing in over
2014-2017, except that Tier 4 would not apply to recreational engines
under 2000 kW (2670 hp). For engines of power ratings not included in
the Tier 3 and Tier 4 tables, the previous tier of standards (Tier 2 or
Tier 3, respectively) continues to apply.

Table III-4.--Proposed Tier 3 Standards for Marine Diesel C1 Commercial Standard Power Density
----------------------------------------------------------------------------------------------------------------
PM g/bhp- NOX+HC g/
Rated kW L/cylinder hr bhp-hr Model year
----------------------------------------------------------------------------------------------------------------
< 19 kW................................................ < 0.9 0.30 5.6 2009
19-< 75 kW............................................. \a\ < 0.9 0.22 5.6 2009
.............. \b\ 0.22 \b\ 3.5 2014
75-3700 kW............................................ < 0.9 0.10 4.0 2012
0.9-< 1.2 0.09 4.0 2013
1.2-< 2.5 \c\ 0.08 4.2 2014
2.5-< 3.5 \c\ 0.08 4.2 2013
3.5-< 7.0 \c\ 0.08 4.3 2012
----------------------------------------------------------------------------------------------------------------
\a\ < 75 kW engines at or above 0.9 L/cylinder are subject to the corresponding 75-3700 kW standards.
\b\ Option: 0.15 PM/4.3 NOX in 2014.

[[Page 15976]]

\c\ This standard level drops to 0.07 in 2018 for < 600 kW engines.

Table III-5.--Proposed Tier 3 Standards for Marine Diesel C1 Recreational and Commercial High Power Density
----------------------------------------------------------------------------------------------------------------
PM g/bhp- NOX+HC g/
Rated kW L/cylinder hr bhp-hr Model year
----------------------------------------------------------------------------------------------------------------
< 19 kW................................................ < 0.9 0.30 5.6 2009
19-< 75 kW............................................. \a\ < 0.9 0.22 5.6 2009
.............. \b\ 0.22 \b\ 3.5 2014
< 0.9 0.11 4.3 2012
75--3700 kW........................................... 0.9-< 1.2 0.10 4.3 2013
1.2-< 2.5 0.09 4.3 2014
2.5-< 3.5 0.09 4.3 2013
3.5-< 7.0 0.09 4.0 2012
----------------------------------------------------------------------------------------------------------------
\a\ < 75 kW engines at or above 0.9 L/cylinder are subject to the corresponding 75-3700 kW standards.
\b\ Option: 0.15 PM/4.3 NOX+HC in 2014.

Table III-6.--Proposed Tier 3 Standards for Marine Diesel C2
----------------------------------------------------------------------------------------------------------------
NOX+HC g/
Rated kW L/cylinder PM g/bhp-hr bhp-hr Model year
----------------------------------------------------------------------------------------------------------------
=< 3700 kW............................................. 7-< 15 0.10 4.6 2013
15-< 20 \a\ 0.20 \a\ 6.5 2014
20-< 25 0.20 7.3 2014
25-< 30 0.20 8.2 2014
----------------------------------------------------------------------------------------------------------------
\a\ For engines at or below 3300 kW in this group, the PM/NOX+HC Tier 3 standards are 0.25/5.2.

Table III-7.--Proposed Tier 4 Standards for Marine Diesel C1 and C2
----------------------------------------------------------------------------------------------------------------
NOX g/bhp-
Rated kW PM g/bhp-hr hr HC g/bhp-hr Model year
----------------------------------------------------------------------------------------------------------------
>3700 kW.............................................. \a\ 0.09 1.3 0.14 2014
0.04 1.3 0.14 \b\ 2016
1400-3700 kW.......................................... 0.03 1.3 0.14 \c\ 2016
600-< 1400 kW.......................................... 0.03 1.3 0.14 \b\ 2017
----------------------------------------------------------------------------------------------------------------
\a\ This standard is 0.19 for engines with 15-30 liter/cylinder displacement.
\b\ Optional compliance start dates are proposed within these model years; see discussion below.
\c\ Option for engines with 7-15 liter/cylinder displacement: Tier 4 PM and HC in 2015 and Tier 4 NOX in 2017.

The proposed Tier 3 standards for engines with rated power less
than 75 kW (100 hp) are based on the nonroad diesel Tier 2 and Tier 3
standards, because these smaller marine engines are largely derived
from (and often nearly identical to) the nonroad engine designs. The
relatively straightforward carry-over nature of this approach also
allows for an early implementation schedule, model year 2009, providing
substantial early benefits to the program. However, some of the less
than 75 kW nonroad engines are also subject to aftertreatment-based
Tier 4 nonroad standards, and our proposal would not carry these over
into the marine sector, due to vessel design and operational
constraints discussed in Section III.D. Because of the preponderance of
both direct- and indirect-injection diesel engines in the 19 to 75 kW
(25-100 hp) engine market today, we are proposing two options available
to manufacturers for meeting Tier 3 standards on any engine in this
range, as indicated in Table III-4. One option focuses on lower PM and
the other on lower NO_X, though both require substantial
reductions in both PM and NO_X and would take effect in 2014.
With important exceptions, we propose that marine diesel engines at
or above 75 kW (100 hp) be subject to new emissions standards in two
steps, Tier 3 and Tier 4. The proposed Tier 3 standards are based on
the engine-out emission reduction potential of the nonroad Tier 4
diesel engines which will be introduced beginning in 2011. Tier 3
standards for C1 engines would generally take effect in 2012, though
for some engines, they would start in 2013 or 2014. We are not basing
our proposed marine Tier 3 emission standards on the existing nonroad
Tier 3 emission standards for two reasons. First, the nonroad Tier 3
engines will be replaced beginning in 2011 with nonroad Tier 4 engines,
and given the derivative nature of marine diesel manufacturing, we
believe it is more appropriate to use those Tier 4 engine capabilities
as the basis for the proposed marine standards. Second, the advanced
fuel and combustion systems that we expect these Tier 4 nonroad engines
to apply will allow approximately a 50 percent reduction in PM when
compared to the reduction potential of the nonroad Tier 3 engines. The
proposed Tier 3 standards levels would vary slightly, from 0.08 to 0.11
g/bhp-hr (0.11 to 0.15 g/kW-hr) for PM and from 4.0 to 4.3 g/bhp-hr
(5.4 to 5.8 g/kW-hr) for NO_X+HC. Tier 3 standards for C2
engines would take effect in 2013 or 2014, depending on engine
displacement, and standards levels would also vary, from 0.10 to 0.25
g/bhp-hr (0.14 to 0.34 g/kW-hr) for PM and 4.6 to 8.2 g/bhp-hr (6.2 to
11.0 g/kW-hr) for NO_X+HC. For the largest C2 engines, those
above 3700 kW (4900 hp), the NO_X+HC standard would remain at
the Tier 2 levels until Tier 4 begins for these engines in 2014.
We are proposing that high-efficiency aftertreatment-based Tier 4
standards be

[[Page 15977]]

applied to all commercial and auxiliary C1 and C2 engines over 600 kW
(800 hp). These standards would phase in over 2014-2017. Marine diesels
over 600 kW, though fewer in number, are the workhorses of the inland
waterway and intercoastal marine industry, running at high load
factors, for many hours a day, over decades of heavy use. As a result
they also account for the very large majority of marine diesel engine
emissions. However, for engines at or below 600 kW, our technical
analysis indicates that applying aftertreatment to them appears at this
time not to be feasible. There are many reasons for this preliminary
conclusion, varying in relative importance with engine size and
application, but generally including insufficient space in below-deck
engine compartments, catalyst packaging limitations for water-injected
exhaust systems, poor catalyst performance in water-jacketed exhaust
systems, and weight constraints in planing hull vessels.
Although with time and investment these issues may be resolvable
for some under 600 kW (800 hp) applications, we are not, at this time,
proposing Tier 4 standards for these engines. We may do so at some
point in the future, such as after the successful prove-out of
aftertreatment in the larger marine engines and in nonroad diesel
engines have established a clearer technology path for extension to
these engines. The approach taken in this proposal concentrates Tier 4
design and development efforts into the engine and vessel applications
where they can do the most good.
We are confident that there is a subset of recreational vessels
that are large enough to accommodate the added size of engines equipped
with aftertreatment and that have appropriate maintenance procedures to
ensure that the aftertreatment systems are appropriately maintained,
for example, because they have a professional crew as opposed to being
maintained by the owner. Based on a review of publicly available sales
literature, we believe that at least the subset of recreational vessels
with engines at rated power above 2000 kW (2760 hp) have the space and
design layout conducive to aftertreatment and professional crews such
that aftertreatment-based standards are feasible. Therefore, we are
proposing to apply the Tier 4 standards to recreational marine diesel
engines at rated power above 2000 kW, but we request comment on whether
this is the appropriate threshold, along with any available information
supporting the commenter's view. We also request comment on the issue
of ULSD availability for these vessels in places that they may visit
outside the United States. The rapid pace at which the industrial
nations are shifting to ULSD has surpassed expectations. By no means
does this ensure its availability in every port that might be
frequented by large U.S. yachts, but it does give confidence that ULSD
will be a global product, and certainly not confined to the coastal
U.S. when Tier 4 yachts begin to appear in 2016. These large yachts are
operated by professional crews who plan their itineraries ahead of time
and are unlikely to put in for fuel without checking out the facility
ahead of time, though quite possibly this may require somewhat more
diligence in the early years of the program while the ULSD-needing
fleet is ramping up in size. We also expect that, from the marinas'
perspective, those frequented by these affluent visitors typically
covet this business today, and will likely be reticent to leave ULSD
off the list of offerings and amenities aimed at attracting them.
We are setting the Tier 4 standards for most engines above 600 kW
(800 hp) at 0.03 g/bhp-hr (0.04 g/kW-hr) for PM, based on the use of PM
filters, and 1.3 g/bhp-hr (1.8 g/kW-hr) for NO_X based on the
use of urea SCR systems. The largest marine diesel engines, those above
3700 kW (4900 hp), would be subject to this SCR-based NO_X
standard in 2014, along with a new engine-based PM standard. The Tier 4
PM standard for these engines would then start in 2016, with the
addition of a filter-based 0.04 g/bhp-hr (0.06 g/kW-hr) standard. See
section III.C(3) for a discussion of the Tier 4 HC standard.
Note that the implementation schedule in the above marine standards
tables is expressed in terms of model years, consistent with past
practice and the format of our regulations. However, in two cases we
believe it is appropriate to provide a manufacturer the option to delay
compliance somewhat, as long as the standards are implemented within
the indicated model year. Specifically, we are proposing to allow a
manufacturer to delay Tier 4 compliance within the 2017 model year for
600-1000 kW (800-1300 hp) engines by up to 9 months (but no later than
October 1, 2017) and, for Tier 4 PM, within the 2016 model year for
over 3700 kW (4900 hp) engines by up to 12 months (but no later than
December 31, 2016). We consider this option to delay implementation
appropriate in order to give some flexibility in spreading the
implementation workload and ensure a smooth transition to the long-term
Tier 4 program.
The proposed Tier 4 standards for locomotives and C2 diesel marine
engines of comparable size are at the same numerical levels but differ
somewhat in implementation schedule, with locomotive Tier 4 starting in
2015 for PM and 2017 for NO_X, and diesel marine Tier 4 for
both PM and NO_X starting in 2016 (for engines in the 1400-
3700 kW (1900-4900 hp) range). We consider these implementation
schedules to be close enough to warrant our providing an option to meet
either schedule for these marine engines, aimed at facilitating the
development of engines for both markets, a common practice today.
Because the locomotive Tier 4 phase-in is offset by only one year on
either side of the marine Tier 4 2016 date, we do not expect this
option to introduce major competitiveness issues between manufacturers
who will be designing engines for both markets and those who will be
designing for only the marine market. Furthermore, we see no reason to
make this option available only those who make locomotive products, and
are therefore proposing its availability to any manufacturer. Comment
is requested on the need for the option, and on whether it should be
limited to a particular subset of engines.
We note too that the Tier 3 marine standards for locomotive-like
marine engines (that is, in the 7-15 liters/cylinder group) although
having the same implementation date and numerical PM standard level as
locomotive Tier 3, includes a 4.6 g/bhp-hr (6.1 g/kW-hr)
NO_X+HC standard, compared to the 5.5 g/bhp-hr (7.3 g/kW-hr)
NO_X standard for locomotive Tier 3. We request comment on
whether some provision is needed to avoid the need for designing an
engine primarily used in locomotives to meet the marine standard in
order to have both ready for Tier 3, on whether sufficient ABT credits
are likely to be available to deal with this, and on how to ensure we
do not lose environmental benefits or inadvertently create
competitiveness problems.
Some marine engine families include engines of the same basic
design and emissions performance but achieving widely varying power
ratings in engine models marketed through varying the number of
cylinders, for example 8 to 20. These families can and do straddle
power cutpoints, most notably at the 3700 kW (4900 hp) cutpoint, above
which NO_X aftertreatment is expected to be needed in 2014
under our proposed standards, and at the 600 kW (800 hp) cutpoint for
application of the proposed Tier 4 standards. We understand that
manufacturers have concerns about additional design and certification work

[[Page 15978]]

needed for an engine family falling into two categories, especially
with regard to the 600 and 3700 kW cutpoints which involve very
different standards or start dates on either side of the cutpoint. We
request comment on whether this concern is a serious one for the
manufacturers, on suggestions for how to address it fairly without a
loss of environmental benefit, and on whether our not addressing it
would cause undesirable shifts in ratings offered in the market in
order to stay on one side or the other of the cutpoints. One particular
idea on which we request comment is allowing engines above 3700 kW an
option to meet the Tier 4 PM requirement in 2014 and the Tier 4
NO_X requirement December 31, 2016, similar to the less than
3700 kW option discussed above.
We are concerned that applying the Tier 4 standards to engines
above 600 kW (800 hp) may create an incentive for vessel builders who
would normally use engines greater than 600 kW to instead use a larger
number of smaller engines in a vessel to get the equivalent power
output. Generally, the choice of engines for a vessel is directly a
function of the work that vessel is intended to do. There may be cases,
however, in which a vessel designer that might have used, for example,
two 630 kW engines, chooses instead to use three 420 kW engines to
avoid the Tier 4 standards. We have concerns about the environmental
impacts of such a result. There also may be competitiveness concerns.
Therefore, we are seeking comment on whether substitution of several
smaller engines for one or two larger engines is likely to occur as a
result of differential standards, and on what can be done to avoid it.
For example, the Tier 4 standards could be applied to engines in multi-
engine vessels with a total power above a certain threshold, such as
1100 kW (1500 hp). We recognize that this would result in a need to
equip engines somewhat below 600 kW with aftertreatment devices, but we
believe the feasibility concerns such as space constraints discussed
above for engines below this cutpoint are diminished in multi-engine
vessel designs. Alternatively, we could require vessel manufacturers
seeking to use more than two engines to make a demonstration to us that
they are not attempting to circumvent the aftertreatment-based
requirements, for example by showing that the vessel design they are
using traditionally incorporates three or more engines or that there is
a specific design requirement that leads to the use of several smaller
engines. A third option would be to base the Tier 4 standards on the
size (or other characteristics) of the vessel, for vessels that have
two or more propulsion engines. Commenters on this issue should address
the feasibility and potential market impacts of these potential
solutions and are asked to offer their own suggestions as well.
(3) Carbon Monoxide, Hydrocarbon, and Smoke Standards
We are not proposing new standards for CO. Emissions of CO are
typically relatively low in diesel engines today compared to non-diesel
pollution sources. Furthermore, among diesel application sectors,
locomotives and marine diesel engines are already subject to relatively
stringent CO standards in Tier 2--essentially 1.5 and 3.7 g/bhp-hr,
respectively, compared to the current heavy-duty highway diesel engine
CO standard of 15.5 g/bhp-hr. Therefore, under our proposal, the Tier 3
and Tier 4 CO standards for all locomotives and marine diesel engines
would remain at current Tier 2 levels and remanufactured Tier 0, 1 and
2 locomotives would likewise continue to be subject to the existing CO
standards for each of these tiers. Although we are not setting more
stringent standards for CO in Tier 4, we note that aftertreatment
devices using precious metal catalysts that we project will be employed
to meet Tier 4 PM, NO_X and HC standards would provide
meaningful reductions in CO emissions as well.
As discussed in section II, HC emissions, often characterized as
VOCs, are precursors to ozone formation, and include compounds that EPA
considers to be air toxics. As for CO, emissions of HC are typically
relatively low in diesel engines today compared to non-diesel sources.
However, in contrast to CO standards, the line-haul locomotive Tier 2
HC standard of 0.30 g/bhp-hr, though comparable to emissions from other
diesel applications in Tier 2 and Tier 3, is more than twice that of
the long-term 0.14 g/bhp-hr standard set for both the heavy-duty
highway 2007 and nonroad Tier 4 programs. For marine diesel engines the
Tier 2 HC standard is expressed as part of a combined NO_X+HC
standard varying by engine size between 5.4 and 8.2 g/bhp-hr, which
clearly allows for high HC levels. Our proposed more stringent Tier 3
NO_X+HC standards for marine diesel engines would likely
provide some reduction in HC emissions, but we expect that the
catalyzed exhaust aftertreatment devices used to meet the proposed Tier
4 locomotive and marine NO_X and PM standards would
concurrently provide very sizeable reductions in HC emissions.
Therefore, in accordance with the Clean Air Act section 213 provisions
outlined in section I.B(3) of this preamble, we are proposing that the
0.14 g/hp-hr HC standard apply for locomotives and marine diesel
engines in Tier 4 as well.
We are proposing that the existing form of the HC standards be
retained through Tier 3. That is, locomotive and marine HC standards
would remain in the form of total hydrocarbons (THC), except for
gaseous- and alcohol-fueled engines (See 40 CFR Sec. 92.8 and Sec.
94.8). Consistent with this, the Tier 3 marine NO_X+HC
standards are proposed to be based on THC, except that Tier 3 standards
for less than 75 kW (100 hp) engines would be based on NMHC, consistent
with their basis in the nonroad engine program. However, we propose
that the Tier 4 HC standards be expressed as NMHC standards, consistent
with aftertreatment-based standards adopted for highway and nonroad
diesel engines.
As in the case of other diesel mobile sources, we believe that
existing smoke standards are of diminishing usefulness as PM levels
drop to very low levels, as engines with PM at these levels emit very
little or no visible smoke. We are therefore proposing to drop the
smoke standards for locomotives and marine engines for any engines
certified to a PM family emission limit (FEL) or standard of 0.05 g/
bhp-hr (0.07 g/kW-hr) or lower. This allows engines certified to Tier 4
PM or to an FEL slightly above Tier 4 to avoid unnecessary testing for smoke.

D. Are the Proposed Standards Feasible?

In this section we describe the feasibility of the various
emissions control technologies we project would be used to meet the
standards proposed today. Because of the range of engines and
applications we cover in this proposal, and because of the technology
that will be available to them for emissions control, our proposed
standards span a range of emissions levels. We have identified a number
of different emissions control technologies we would expect to be used
to meet the proposed standards. These technologies range from
incremental improvements to existing engine components for the proposed
remanufacturing program to highly advanced catalytic exhaust treatment
systems similar to those expected to be used to control emissions from
heavy-duty diesel trucks and nonroad equipment.
In this section we first describe the feasibility of emissions
control technologies we project would be used

[[Page 15979]]

to meet the standards we are proposing for existing engines that are
remanufactured as new (i.e., Tier 0, Tier 1, Tier 2). We also describe
how these same technologies would be applied to meet our proposed
interim standards for new engines (i.e., Tier 3). We conclude this
section with a discussion of catalytic exhaust treatment technologies
projected to be used to meet our proposed Tier 4 standards. A more
detailed analysis of these technologies and the issues related to their
application to locomotive and marine diesel engines can be found in the
draft Regulatory Impact Analysis (RIA).
(1) Emissions Control Technologies for Remanufactured Engine Standards
and for New Tier 3 Engine Standards
In the locomotive sector, emissions standards already exist for
engines that are remanufactured as new. Some of these engines were
originally unregulated (i.e. Tier 0), and others were originally built
to earlier emissions standards (Tier 1 and Tier 2). We are proposing
more stringent standards for these engines that apply whenever the
locomotives are remanufactured as new. Our proposed remanufactured
standards apply to locomotive engines that were originally built as
early as 1973.
We project that incremental improvements to existing engine
components would be feasible to meet our proposed locomotive
remanufactured engine standards. In many cases, similar improvements to
these have already been implemented on newly built locomotives to meet
our current new locomotive standards. To meet the lower NO_X
standard proposed for the Tier 0 locomotive remanufacturing program, we
expect that improvements in fuel system design, engine calibration and
optimization of existing after-cooling systems may be used to reduce
NO_X from the current 9.5 g/bhp-hr Tier 0 standard to 7.4 g/
bhp-hr. These are the same technologies used to meet the current Tier 1
NO_X emission standard of 7.4 g/bhp-hr. In essence,
locomotive manufacturers will duplicate current Tier 1 locomotive
NO_X emission solutions and adapt those same solutions to the
portion of the existing Tier 0 fleet that can accommodate them. For
older Tier 0 locomotives manufactured without separate-circuit cooling
systems for intake air charge air cooling, reaching the Tier 1
NO_X level will not be possible. For these engines 8.0 g/hp-
hr NO_X emissions represents the lowest achievable level.
To meet all of our proposed PM standards for the remanufacturing
program and for the new locomotive Tier 3 interim standard, we expect
that lubricating oil consumption controls will be implemented, along
with the ultra low sulfur diesel fuel requirement for locomotive
engines (which was previously finalized in our nonroad clean diesel
rulemaking). Because of the significant fraction of lubricating oil
present in PM from today's locomotives, we believe that existing low-
oil-consumption piston ring-pack designs, when used in conjunction with
improvements to closed crankcase ventilation systems, will provide
significant, near-term PM reductions. These technologies can be applied
to all locomotive engines, including those built as far back as 1973.
And based upon our on-highway and nonroad clean diesel experience, we
also believe that the use of ultra low sulfur diesel fuel in the
locomotive sector will assist in meeting the Tier 2 remanufacturing and
Tier 3 PM standards. We believe that the combination of reduced sulfate
PM and improvement of oil and crankcase emission control to near Tier 3
nonroad or 2007 heavy-duty on-highway levels will provide an
approximately 50% reduction in PM emissions.
We believe that some fraction of the remanufacturing systems can be
developed and certified as early as 2008, so we are proposing the
required usage of Tier 0, Tier 1 and Tier 2 emission control systems as
soon as they are available starting in 2008. However, we estimate that
it will take approximately 3 years to complete the development and
certification process for all of the Tier 0 and Tier 1 emission control
systems, so we have proposed full implementation of the Tier 0 and Tier
1 remanufactured engine standards in 2010. We base this lead time on
the types of technology that we expect to be implemented, and on the
amount of lead time locomotive manufacturers needed to certify similar
systems for our current remanufacturing program. The new engine changes
necessary to meet the Tier 3 and remanufactured Tier 2 PM emission
standards will require additional engine changes leading us to propose
an implementation date for those engines of 2012 for Tier 3 engines and
2013 for remanufactured Tier 2 engines. These changes include further
improvements to ring pack designs--especially for two-stroke engines,
and the implementation of high efficiency crankcase ventilation
systems. These technologies are described and illustrated in detail in
our draft Regulatory Impact Analysis.
In the marine sector, emissions standards do not currently exist
for engines that are remanufactured as new. In today's proposal, we are
requesting comment on a marine diesel engine remanufacturing program
that would apply to some of these marine engines whenever they are
remanufactured as new (see section VII.A(2)). Because we are requesting
comment on a marine engine remanufacturing program that essentially
parallels our locomotive remanufacturing program, we expect that the
same emissions control technologies described above would be
implemented for remanufactured marine diesel engines just as for
remanufactured locomotive engines.
We are proposing more stringent emissions standards for all newly
built marine diesel engines that have a displacement of less than
thirty liters per cylinder. For marine diesel engines that are either
used in recreational vessels or are rated to produce less than 600 kW
of power, we are proposing emissions standards that likely would not
require the use of catalytic exhaust treatment technology. We are also
proposing similar standards, as interim standards, for marine diesel
engines that are used in commercial vessels and are rated to produce
600 kW of power or more (except if greater than 3700 kW). Collectively,
we refer to these standards as our Tier 3 marine diesel engine standards.
To meet our proposed Tier 3 marine diesel engine standards, we
believe that engine manufacturers will utilize incremental improvements
to existing engine components. To meet the lower NO_X
standards we expect that improvements in fuel system design and engine
calibration will be implemented. For Category 1 engines from 75 kW
through 560 kW, these technologies would be similar to designs and
calibrations that likely will be used to meet our nonroad Tier 4
standards for engines. For Category 1 engines below 75 kW and greater
than 560kW, and for Category 2 engines that have cylinder displacements
less than 15 L/cylinder, these technologies are similar to designs that
will be used to meet our nonroad Tier 3 standards, and our proposed
locomotive Tier 3 standards.
In almost all instances, marine diesel engines are derivative of
land based nonroad engines or locomotive engines. In order to meet our
nonroad Tier 4 emission levels (phased in from 2011-2015), nonroad
engines will see significant base engine improvements designed to
reduce engine-out emissions. Refer to our nonroad Tier 4 rulemaking for
details on the designs and calibrations we expect to be used to meet
the Tier 3 standards we are proposing for the lower horsepower marine
engines. For example, we expect

[[Page 15980]]

marine engines to utilize high-pressure, common-rail fuel injection
systems or improvements in unit injector design. When such fuel system
improvements are used in conjunction with engine mapping and
calibration optimization, the Tier 3 marine diesel engine standards can
be met. Since this technology and these components already have been
implemented on on-highway, nonroad, and some locomotive engines, they
can be applied to marine engines beginning as early as 2009.
Because some marine engines are not as similar to on-highway,
nonroad or locomotive engines as others, we believe that full
implementation of these technologies for marine engines cannot be
accomplished until 2012. We expect that the PM emissions control
technologies that will be used to meet our proposed Tier 3 marine
diesel engine standards will be similar to the technology used to meet
our nonroad Tier 3 PM standards and our proposed locomotive Tier 3 PM
standards. That is, we believe that a combination of fuel injection
improvements, plus the use of existing low-oil-consumption piston ring-
pack designs and improved closed crankcase ventilation systems will
provide significant PM reductions. And based upon our on-highway and
non-road clean diesel experience, we also believe that the use of ultra
low sulfur diesel fuel in the marine sector will assist in meeting the
Tier 3 PM standards.
Because all of the aforementioned technologies to reduce
NO_X and PM emissions can be developed for production,
certified, and introduced into the marine engine sector without
extended lead-time, we believe that these technologies can be
implemented for some engines as early as 2009, and for all engines by
2014. We believe that this later date is needed only for those marine
engines that are not similar to other on-highway, nonroad, or
locomotive engines.
(2) Catalytic Exhaust Treatment Technologies for New Engines
For marine diesel engines in commercial service that are greater
than 600 kW, for all marine engines greater than 2000 kW, and for all
locomotives, we are proposing stringent Tier 4 standards based on the
use of advanced catalytic exhaust treatment systems to control both PM
and NO_X emissions. There are four main issues to address
when analyzing the application of this technology to these new sources:
the efficacy of the fundamental catalyst technology in terms of the
percent reduction in emissions given certain engine conditions such as
exhaust temperature; its applicability in terms of packaging; its long-
term durability; and whether or not the technology significantly
impacts an industry's supply chain infrastructure--especially with
respect to supplying urea reductant for SCR to locomotives and vessels.
We have carefully examined these points, and based upon our analysis
(detailed in our draft Regulatory Impact Analysis), we believe that we
have identified robust PM and NO_X catalytic exhaust
treatment systems that are applicable to locomotives and marine engines
that also pose a manageable impact on the rail and marine industries'
infrastructure.
(a) Catalytic PM Emissions Control Technology
The most effective exhaust aftertreatment used for diesel PM
emissions control is the diesel particulate filter (DPF). More than a
million light diesel vehicles that are OEM-equipped with DPF systems
have been sold in Europe, and over 200,000 DPF retrofits to diesel
engines have been conducted worldwide.\103\ Broad application of
catalyzed diesel particulate filter (CDPF) systems with greater than 90
percent PM control is beginning with the introduction of 2007 model
year heavy-duty diesel trucks in the United States. These systems use a
combination of both passive and active soot regeneration. CDPF systems
utilizing metal substrates are a further development that trades off a
degree of elemental carbon soot control for reduced backpressure,
improvements in the ability of the trap to clear oil ash, greater
design freedom regarding filter size/shape, and greater robustness.
Metal-CDPFs were initially introduced as passive-regeneration retrofit
technologies for diesel engines designed to achieve approximately 60
percent control of PM emissions. Recent data from further development
of these systems for Euro-4 truck applications has shown that metal-
CDPF trapping efficiency for elemental carbon PM can exceed 70 percent
for engines with inherently low elemental carbon emissions.\104\ Data
from locomotive testing confirms a relatively low elemental carbon
fraction and relatively high organic fraction for PM emissions from
medium-speed Tier 2 locomotive engines.\105\ The use of an oxidizing
catalyst with platinum group metals (PGM) coated directly to the CPDF
combined with a diesel oxidation catalyst (DOC) mounted upstream of the
CDPF would provide 95 percent or greater removal of HC, including the
semi-volatile organic compounds that contribute to PM. Such systems
would reduce overall PM emissions from a locomotive or marine diesel
engine by upwards of 90 percent.
---------------------------------------------------------------------------

\103\ ``Diesel Particulate Filter Maintenance: Current Practices
and Experience'', Manufacturers of Emission Controls Association,
June 2005, http://meca.org/galleries/default-file/
Filter_Maintenance_White_Paper_605_final.pdf.
\104\ Jacob, E., L[auml]mmerman, R., Pappenheimer, A., Rothe, D.
``Exhaust Gas Aftertreatment System for Euro 4 Heavy-duty Engines'',
MTZ, June, 2006.
\105\ Smith, B., Sneed, W., Fritz, S. ``AAR Locomotive Emissions
Testing 2005 Final Report''.
---------------------------------------------------------------------------

We believe that locomotive and marine diesel engine manufacturers
will benefit from the extensive development taking place to implement
DPF technologies in advance of the heavy-duty truck and nonroad PM
standards in Europe and the U.S. Given the steady-state operating
characteristics of locomotive and marine engines, DPF regeneration
strategies will certainly be capable of precisely controlling PM under
all conditions and passively regenerating whenever the exhaust gas
temperature is >250 [deg]C. Therefore, we believe that the Tier 4 PM
standards we are proposing for locomotive and marine diesel engines are
technologically feasible. And given the level of activity in the on-
highway and nonroad sectors to implement DPF technology, we believe
that our proposed implementation dates for locomotive and marine diesel
engines are appropriate and achievable.
(b) Catalytic NO_X Emissions Control Technology
We have analyzed a variety of technologies available for
NO_X reduction to determine their applicability to diesel
engines in the locomotive and marine sectors. As described in more
detail in our draft RIA, we are assuming locomotive and marine diesel
engine manufacturers will choose to use--Selective Catalytic Reduction,
or SCR to comply with our proposed standards. SCR is a commonly used
aftertreatment device for meeting stricter NO_X emissions
standards in diesel applications worldwide. Stationary power plants
fueled with coal, diesel, and natural gas have used SCR for three
decades as a means of controlling NO_X emissions, and
currently, European heavy-duty truck manufacturers are using this
technology to meet Euro 5 emissions limits. To a lesser extent, SCR has
been introduced on diesel engines in the U.S. market, but the
applications have been limited to marine ferryboat and stationary
electrical power generation demonstration projects in California and

[[Page 15981]]

several of the Northeast states. However, by 2010, when 100 percent of
the heavy-duty diesel trucks are required to meet the NO_X
limits of the 2007 heavy-duty highway rule, several heavy-duty truck
engine manufacturers have indicated that they will use SCR
technology.\106\ \107\ While other promising NO_X-reducing
technologies such as lean NO_X catalysts, NO_X
adsorbers, and advanced combustion control continue to be developed
(and may be viable approaches to the standards we are proposing today),
our analysis assumes that SCR will be the technology of choice in the
locomotive and marine diesel engine sectors.
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\106\ ``Review of SCR Technologies for Diesel Emission Control:
European Experience and Worldwide Perspectives,'' presented by Dr.
Emmanuel Joubert, 10th DEER Conference, July 2004.
\107\ Lambert, C., ``Technical Advantages of Urea SCR for Light-
Duty and Heavy-Duty Diesel Vehicle Applications,'' SAE Technical
Paper 2004-01-1292, 2004.
---------------------------------------------------------------------------

An SCR catalyst reduces nitrogen oxides to elemental nitrogen
(N₂) and water by using ammonia (NH₃) as the
reducing agent. The most-common method for supplying ammonia to the SCR
catalyst is to inject an aqueous urea-water solution into the exhaust
stream. In the presence of high-temperature exhaust gasses (>200
[deg]C), the urea hydrolyzes to form NH₃ and CO₂.
The NH₃ is stored on the surface of the SCR catalyst where
it is used to complete the NO_X-reduction reaction. In
theory, it is possible to achieve 100 percent NO_X conversion
if the NH₃-to-NO_X ratio (a) is 1:1 and the
space velocity within the catalyst is not excessive. However, given the
space limitations in packaging exhaust aftertreatment devices in mobile
applications, an a of 0.85-1.0 is often used to balance the need
for high NO_X conversion rates against the potential for
NH₃ slip (where NH₃ passes through the catalyst
unreacted). The urea dosing strategy and the desired a are
dependent on the conditions present in the exhaust gas; namely
temperature and the quantity of NO_X present (which can be
determined by engine mapping, temperature sensors, and NO_X
sensors). Overall NO_X conversion efficiency, especially
under low-temperature exhaust gas conditions, can be improved by
controlling the ratio of two NO_X species within the exhaust
gas; NO₂ and NO. This can be accomplished through use of an
oxidation catalyst upstream of the SCR catalyst to promote the
conversion of NO to NO₂. The physical size and catalyst
formulation of the oxidation catalyst are the principal factors that
control the NO₂-to-NO ratio, and by extension, improve the
low-temperature performance of the SCR catalyst.
Recent studies have shown that an SCR system is capable of
providing well in excess of 80 percent NO_X reduction
efficiency in high-power, diesel applications.\108110\ SCR catalysts
can achieve significant NO_X reduction throughout much of the
exhaust gas temperature operating range observed in locomotive and
marine applications. Collaborative research and development activities
between diesel engine manufacturers, truck manufacturers, and SCR
catalyst suppliers have also shown that SCR is a mature, cost-effective
solution for NO_X reduction on diesel engines in other mobile
sources. While many of the published studies have focused on highway
truck applications, similar trends, operational characteristics, and
NO_X reduction efficiencies have been reported for marine and
stationary applications as well.\111\ Given the preponderance of
studies and data--and our analysis summarized here and detailed in the
draft RIA--we believe that this technology is appropriate for
locomotive and marine diesel applications. Furthermore, we believe that
locomotive and marine diesel engine manufacturers will benefit from the
extensive development taking place to implement SCR technologies in
advance of the heavy-duty truck NO_X standards in Europe and
the U.S. The urea dosing systems for SCR, already in widespread use
across many different diesel applications, are expected to become more
refined, robust, and reliable in advance of our proposed Tier 4
locomotive and marine standards. Given the steady-state operating
characteristics of locomotive and marine engines, SCR NO_X
control strategies will certainly be capable of precisely controlling
NO_X under all conditions whenever the exhaust gas
temperature is greater than 150 [deg]C.
---------------------------------------------------------------------------

\108\ Walker, A.P. et al., ``The Development and In-Field
Demonstration of Highly Durable SCR Catalyst Systems,'' SAE 2004-01-1289.
\109\ Conway, R. et al., ``Combined SCR and DPF Technology for
Heavy Duty Diesel Retrofit,'' SAE Technical Paper 2005-01-1862, 2005.
\110\ ``The Development and On-Road Performance and Durability
of the Four-Way Emission Control SCRTTM System,'' presented by Andy
Walker, 9th DEER Conference, August 28, 2003.
\111\ Telephone conversation with Gary Keefe, Argillon, June 6, 2006.
---------------------------------------------------------------------------

To ensure that we have the most up-to-date information on urea SCR
NO_X technologies and their application to locomotive and
marine engines, we have met with a number of locomotive and marine
engine manufacturers, as well as manufacturers of catalytic
NO_X emissions control systems. Through our discussions we
have learned that some engine manufacturers currently perceive some
risk regarding urea injection accuracy and long-term catalyst
durability, both of which could result in either less efficient
NO_X reduction or ammonia emissions. We have carefully
investigated these issues, and we have concluded that accurate urea
injection systems and durable catalysts already exist and have been
applied to urea SCR NO_X emissions control systems that are
similar to those that we expect to be implemented in locomotive and
marine applications.
Urea injection systems applied to on-highway diesel trucks and
diesel electric power generators already ensure accurate injection of
urea, and these applications have similar--if not more dynamic--engine
operation as compared to locomotive and marine engine operation. To
ensure accurate urea injection across all engine operating conditions,
these systems utilize NO_X sensors to maintain closed-loop
feedback control of urea injection. These NO_X sensor-based
feedback control systems are similar to oxygen sensor-based systems
that are used with catalytic converters on virtually every gasoline
vehicle on the road today. We believe these NO_X sensor based
control systems are directly applicable to locomotive and marine engines.
Ammonia emissions, which are already minimized through the use of
closed-loop feedback urea injection, can be all-but-eliminated with an
oxidation catalyst downstream of the SCR catalyst. Such catalysts are
in use today and have been shown to be 95% effective at reducing
ammonia emissions.
Catalyst durability is affected by sulfur and other chemicals that
can be present in some diesel fuel and lubricating oil. These chemicals
have been eliminated in other applications by the use of ultra-low
sulfur diesel fuel and low-SAPS (sulfated ash, phosphorous, and sulfur)
lubricating oil. Locomotive and marine operators already will be using
ultra low sulfur diesel by the time urea NO_X SCR systems
would be needed, and low SAPS oil can be used in locomotive and marine
engines. Thermal and mechanical vibration durability of catalysts has
been addressed through the selection of proper materials and the design
of support and mounting structures that are capable of withstanding the
shock and vibration levels present in locomotive and marine
applications. More details on catalyst durability and urea injection
accuracy are available in the remainder of this section and also in our
draft RIA.

[[Page 15982]]

Even though we believe that the issues of catalyst durability and
urea injection accuracy have been addressed in existing NO_X
SCR emissions control systems, we invite comments and the submission of
additional information and data regarding catalyst durability and urea
injection accuracy.
(c) Durability of Catalytic PM and NO_X Emissions Control
Technology
Published studies indicate that SCR systems should experience very
little deterioration in NO_X conversion throughout the life-
cycle of a diesel engine.\112\ The principal mechanism of deterioration
in an SCR catalyst is thermal sintering--the loss of catalyst surface
area due to the melting and growth of active catalyst sites under high-
temperature conditions (as the active sites melt and combine, the total
number of active sites at which catalysis can occur is reduced). This
effect can be minimized by design of the SCR catalyst washcoat and
substrate for the exhaust gas temperature window in which it will
operate. Another mechanism for catalyst deterioration is catalyst
poisoning--the plugging and/or chemical de-activation of active
catalytic sites. Phosphorus from the engine oil and sulfur from diesel
fuel are the primary components in the exhaust stream which can de-
activate a catalytic site. The risk of catalyst deterioration due to
sulfur poisoning will be all but eliminated with the 2012
implementation of ULSD fuel (< 15 ppm S) for locomotive and marine
applications. Catalyst deterioration due to phosphorous poisoning can
be reduced through the use of engine oil with low sulfated-ash,
phosphorus, and sulfur content (low-SAPS oil) and through reduced
engine oil consumption. The high ash content in current locomotive and
marine engine oils is related to the need for a high total base number
(TBN) in the oil formulation. Because today's diesel fuel has
relatively high sulfur levels, a high TBN in the engine oil is
necessary today to neutralize the acids created when fuel-borne sulfur
migrates to the crankcase. With the use of ULSD fuel, acid formation in
the crankcase will not be a significant concern. The low-SAPS oil will
be available for on-highway use by October 2006 and is specified by the
American Petroleum Institute as ``CJ-4.'' We also expect that Tier 3
locomotive and marine engine designs will have reduced oil consumption
in order to meet the Tier 3 PM standards, and that the Tier 4 designs
will be an evolutionary development that will apply catalytic exhaust
controls to the Tier 3 engine designs. The durability of other exhaust
aftertreatment devices, namely the DOC and CDPF, will also benefit from
the use of ULSD fuel, reduced oil consumption and low-SAPS engine oil
because the reduction in exposure of these devices to sulfur and
phosphorous will improve their effectiveness and the reduction in ash
loading will increase the CDPF ash-cleaning intervals.
---------------------------------------------------------------------------

\112\ Conway, R. et al., ``NO_X and PM Reduction Using
Combined SCR and DPF Technology in Heavy Duty Diesel Applications,''
SAE Technical Paper 2005-01-3548, 2005.
---------------------------------------------------------------------------

(d) Packaging of Catalytic PM and NO_X Emissions Control Technology
We project that locomotive manufacturers will need to re-package/
re-design the exhaust system components to accommodate the
aftertreatment system. Our analysis shows the packaging requirements
for the aftertreatment system are such that they can be accommodated
within the envelope defined by the Association of American Railroads
(AAR) Plate ``L'' clearance diagram for freight locomotives.\113\
Typical volume required for the SCR catalyst and post-SCR ammonia slip
catalyst for Euro V and U.S. 2010 heavy-duty truck applications is
approximately 2 times the engine displacement, and the upstream DOC/
CDPF volume is approximately 1-1.5 times the engine displacement. Due
to the longer useful life and maintenance intervals required for
locomotive applications, we estimate that the SCR catalyst volume will
be sized at approximately 2.5 times the engine displacement, and the
combined DOC/CDPF volume will be approximately 1.7 times the engine
displacement. For an engine with 6 ft\3\ of total displacement, the
volume requirement for the aftertreatment components would be
approximately 25 ft\3\. EPA engineers have examined Tier 2 EMD and GE
line-haul locomotives and conclude that there is adequate space to
package these components. This conclusion also applies to new switcher
locomotives, which, while being shorter in length than line-haul
locomotives, will also be equipped with smaller, less-powerful
engines--resulting in smaller volume requirements for the
aftertreatment components. Given the space available on today's
locomotives, we feel that packaging catalytic PM and NO_X
emissions control technology on-board locomotives is actually less
challenging than packaging similar technology on-board other mobile
sources such as light-duty vehicles, heavy-duty trucks, and nonroad
equipment. Given that similar exhaust systems are either already
implemented on-board these vehicles or will be implemented on these
vehicles years before similar systems would be required on-board
locomotives, we believe that any packaging issues would be successfully
addressed early in the locomotive redesign process.
---------------------------------------------------------------------------

\113\ ``AAR Manual of Standards and Recommended Practices,''
Standard S-5510, Association of American Railroads.
---------------------------------------------------------------------------

For commercial vessels that use marine diesel engines greater than
600 kW, we expect that marine vessel builders will need to re-package
and re-design the exhaust system components to accommodate the
aftertreatment components expected to be necessary to meet the proposed
standards. Our discussions with marine architects and engineers, along
with our review of vessel characteristics, leads us to conclude for
commercial marine vessels, adequate engine room space can be made
available to package aftertreatment components. Packaging of these
components, and analyzing their mass/placement effect on vessel
characteristics, will become part of the design process undertaken by
marine architecture firms.\114\
---------------------------------------------------------------------------

\114\ Telephone conversation between Brian King, Elliot Bay
Design Group, and Brian Nelson, EPA, July 24, 2006.
---------------------------------------------------------------------------

We did determine, however, that for recreational vessels and for
vessels equipped with engines less than 600 kW, catalytic PM and
NO_X exhaust treatment systems were less practical from a
packaging standpoint than for the larger, commercially operated
vessels. We did identify catalytic emissions control systems that would
significantly reduce emissions from these smaller vessels. However,
after taking into consideration costs, energy, safety, and other
relevant factors, we identified a number of reasons why we are not
proposing at this time any standards that would likely require
catalytic exhaust treatment systems on these smaller vessels. One
reason is that most of these vessels use seawater (fresh or saltwater)
cooled exhaust systems, and even seawater injection into their exhaust
systems, to cool engine exhaust to prevent overheating materials such
as a fiberglass hull. This current practice of cooling and seawater
injection could reduce the effectiveness of catalytic exhaust treatment
systems. This is significantly more challenging than for gasoline
catalyst systems due to much larger relative catalyst sizes and cooler
exhaust temperatures typical of diesel engines. In addition, because of
these

[[Page 15983]]

vessels' small size and their typical design to operate by planing high
on the surface of the water, catalytic exhaust treatment systems pose
several significant packaging and weight challenges. Normally, such
packaging and weight challenges would be addressed by the use of
lightweight hull and superstructure materials. However, the currently
accepted lightweight vessel materials are incompatible with the
temperatures required to sustain catalyst effectiveness. One solution
could be new lightweight hull and superstructure materials which would
have to be developed, tested and approved prior to their application on
vessels using catalytic exhaust treatment systems. Given these issues,
we believe it is prudent to not propose catalytic exhaust treatment-
based emission standards for marine diesel engines below 600 kW at this
time.
(e) Infrastructure Impacts of Catalytic PM and NO_X Emissions
Control Technology
For PM trap technology the locomotive and marine industries will
have minimal impact imposed upon their industries' infrastructures.
Since PM trap technology relies on no separate reductant, any
infrastructure impacts would be limited to some minor changes in
maintenance practices or maintenance facilities. Such maintenance would
be limited to the infrequent process of removing lubricating oil ash
buildup from within a PM trap. This type of maintenance might require
facilities to remove PM traps for cleaning. This might involve the use
of a crane or other lifting device. We understand that much of this
kind of infrastructure already exists for other locomotive and marine
engine maintenance practices. We have toured shipyards and locomotive
maintenance facilities at rail switchyards, and we observed that such
facilities are generally already adequate for any required PM trap
maintenance.
We do expect some impact on the railroad and marine sectors to
accommodate the use of a separate reductant for use in a NO_X
SCR system. For light-duty, heavy-duty, and nonroad applications, the
preferred reductant in an SCR system is a 32.5 percent urea-water
solution. The 32.5 percent solution, also known as the ``eutectic''
concentration, provides the lowest freezing point (-11 [deg]C or 12
[deg]F) and assures that the ratio of urea-to-water will not change
when the solution begins to freeze.\115\ Heated storage tanks and
insulated dispensing equipment may be necessary to prevent freeze-up in
Northern climates. In addition, the urea dosing apparatus (urea storage
tank, pump, and lines) onboard the locomotive or marine vessel may
require similar protections. Locomotives and marine vessels are
commonly refueled from large, centralized fuel storage tanks, tanker
trucks, or tenders with long-term purchase agreements. Urea suppliers
will be able to distribute urea to the locomotive and marine markets in
a similar manner, or they may choose to employ multi-compartment diesel
fuel/urea tanker trucks for delivery of both products simultaneously.
The frequency that urea needs to be added will be dependent on the urea
storage capacity, duty-cycle, and urea dosing rate for each
application. Discussions concerning the urea infrastructure in North
America and specifications for an emissions-grade urea solution are now
under way amongst light- and heavy-duty on-highway diesel stakeholders.
---------------------------------------------------------------------------

\115\ Miller, W. et al., ``The Development of Urea-SCR Technology for
U.S. Heavy Duty Trucks,'' SAE Technical Paper 2000-01-0190, 2000.
---------------------------------------------------------------------------

Although an infrastructure for widespread transportation, storage,
and dispensing of SCR-grade urea does not currently exist in the U.S.,
the affected stakeholders in the light- and heavy-duty on-highway and
nonroad diesel sectors are expected to follow the European model, in
which diesel engine/truck manufacturers and fuel refiners/distributors
formed a collaborative working group known as ``AdBlue.'' The goal of
the AdBlue organization is to resolve potential problems with the
supply, handling, and distribution of urea and to establish standards
for product purity.\116\ Concerning urea production capacity, the U.S.
has more-than-sufficient capacity to meet the additional needs of the
rail and marine industries. For example, in 2003, the total diesel fuel
consumption for Class I railroads was approximately 3.8 billion
gallons.\117\ If 100 percent of the Class I locomotive fleet were
equipped with SCR catalysts, approximately 190 million gallons-per-year
of 32.5 percent urea-water solution would be required.\118\ It is
estimated that 190 million gallons of urea solution would require 0.28
million tons of dry urea (1 ton dry urea is needed to produce 667
gallons of 32.5 percent urea-water solution). Currently, the U.S.
consumes 14.7 million tons of ammonia resources per year, and relies on
imports for 41 percent of that total (of which, urea is the principal
derivative). In 2005 domestic ammonia producers operated their plants
at 66 percent of rated capacity, resulting in 4.5 million tons of
reserve production capacity.\119\ In the hypothetical situation above,
where 100 percent of the locomotive fleet required urea, only 6.2
percent of the reserve domestic capacity would be needed to satisfy the
additional demand. A similar analysis for the marine industry, with a
yearly diesel fuel consumption of 2.2 billion gallons per year, would
not significantly impact the urea demand-to-reserve capacity equation.
Since the rate at which urea-SCR technology is introduced to the
railroad and marine markets will be gradual--and the reserve urea
production capacity is more-than-adequate to meet the expected demand
in the 2017 timeframe--EPA does not project any urea cost or supply
issues will result from implementing the proposed Tier 4 standards.
---------------------------------------------------------------------------

\116\ ``Ensuring the Availability and Reliability of Urea Dosing
for On-Road and Non-Road,'' presented by Glenn Barton, Terra Corp.,
9th DEER Conference, August 28, 2003.
\117\ ``National Transportation Statistics--2004,'' Table 4-5,
U.S. Bureau of Transportation Statistics.
\118\ Assuming the dosing rate of 32.5 percent urea-water
solution is 5 percent of the total fuel consumed; 3.8 billion
gallons of diesel fuel * 0.05 = 190 million gallons of urea-water solution.
\119\ ``Mineral Commodity Summaries 2006,'' page 118, U.S. Geological
Survey, http://www.minerals.usgs.gov/minerals/pubs/mcs/mcs2006.pdf.

---------------------------------------------------------------------------

(3) The Proposed Standards Are Technologically Feasible
Our proposal covers a wide range of engines and the implementation
of a range of emissions controls technologies, and we have identified a
range of technologically feasible emissions control technologies that
likely would be used to meet our proposed standards. Some of these
technologies are incremental improvements to existing engine
components, and many of these improved components have already been
applied to similar engines. The other technologies we identified
involve catalytic exhaust treatment systems. For these technologies we
carefully examined the catalyst technology, its applicability to
locomotive and marine engine packaging constraints, its durability with
respect to the lifetime of today's locomotive and marine engines, and
its impact on the infrastructure of the rail and marine industries.
From our analysis, which is presented in detail in our draft RIA, we
conclude that incremental improvements to engine components and the
implementation of catalytic PM and NO_X exhaust treatment
technology would be feasible to meet our proposed emissions standards.

[[Page 15984]]

(4) A Request for Detailed Technical Comments
We have carried out an extensive outreach program with the
regulated industry to understand the potential impacts and technical
challenges to the application of aftertreatment technology to diesel
locomotives and marine engines. We are requesting comments on all parts
of our resulting analyses summarized in the preceding sections and
presented in greater detail in the Draft RIA.
Further, we request comment on the following list of detailed
questions provided to the Agency by a stakeholder regarding particular
challenges in applying aftertreatment technologies to diesel
locomotives. Some of these questions raise concerns about the
feasibility of the proposed Tier 4 standards under specific
environmental conditions. We present theses questions without endorsing
the appropriateness of applying these conditions to locomotive catalyst
designs. The reader should refer to the preceding sections and the
draft RIA for our analyses of the relevant issues.
(1) How do the following attributes of the locomotive exhaust
environment impact the ability of a Zeolite SCR type catalyst to
operate within 10% of its ``as new'' conversion efficiency (~94%) after
34,000 MW-hours of operation?
? 150 hours per year operation at 600 Celsius exhaust
temperature at the inlet to the SCR, due to DPF regeneration.'' (20-
minute regeneration every 20 hours of operation).
? 120 minutes per year operation at 700 Celsius.
? oot exposure equal to 0.03 g/bhp-hr.
? Shock loading averaging 1,000 mechanical shock pulses per
year due to hard coupling.
? Extended periods of vibration where the vibration load on the
catalysts can reach 6G and 1000 Hz.
? Water exposure due to rains, icing, water spray and condensed
frozen or liquid water during 20% of its life.
? Salt fog consisting of 5 ± 1% salt concentration
by weight with fallout rate between 0.00625 and 0.0375 ml/cm\2\/hr.
? The catalysts will be subject to sands composed of 95% of
SiO₂ with particle size between 1 to 650 microns in diameter
with sand concentration of 1.1 ± 0.25 g/m\3\ and air
velocity of 29 m/s (104 km/h).
? Exposure to dusts comprised of red china clay and silicon
flour of particle sizes that are between 1 to 650 microns in diameter
with dust concentration of 10.6 ± 7 g/m\3\ with a velocity
equal to locomotive motion velocity on catalyst surfaces.
(2) Is it feasible for a Zeolite SCR catalyst (as compared to the
Vanadium-based catalysts) to operate within 10% of its as new
conversion efficiency (~94%) after sustained exposure to real exhaust?
If it is, why is it feasible? If it is not feasible, please explain why
it is not.
(3) Is it feasible to maintain the conversion efficiency of a
diesel oxidation catalyst at least at 45% in the same catalyst
environment described in (1) above? In your comments, please explain
why or why not.
(4) The feasibility of achieving low ammonia slip, i.e., less than
5 ppm, from urea-based SCR systems that dose at or above 1:1 ratios
when applied to an exhaust stream with 500-600 ppm NO_X under
both steady state and transient load conditions.
(5) The feasibility of a reliable NO_X sensor with 5%
accuracy to control urea dosing sufficiently to achieve a 95%
NO_X conversion efficiency using a Zeolite-based SCR when not
kinetically limited.
(6) The expected level of ammonia slip catalyst selectivity back to
NO_X when a Zeolite-based SCR is dosed at 1:1 ratios and
applied to diesel engines above 3.0 MW with an exhaust stream of 500-
600 ppm NO_X.
(7) The effect on overall locomotive weight and balance when
applying DPF and SCR devices with a weight in excess of 8000 lbs and
volume in excess of 40 cubic feet mounted above the engine.
(8) The expected effect on locomotive operating range when adding
urea storage equal to 5% of locomotive fuel capacity and a 2% decrease
in locomotive fuel efficiency.
(9) Incidental emissions generation resulting from the production
and distribution of urea for railroad usage (200,000,000 gallons/year).
(10) The comparative performance of a given engine on the marine v.
locomotive duty cycle to include an assessment of SCR technologies
(i.e., Zeolilte v. Vanadium), expected effectiveness for each
application, and any considerations that may be unique for one
application versus the other that could impact overall NO_X
conversion effectiveness.
(11) The impact of the proposed Tier 4 NO_X limit of 1.3
g/hp-hr versus incrementally higher limits on fuel burn and greenhouse
gas emissions.
EPA notes that many of these issues are addressed elsewhere in the
preamble and in the draft RIA. We invite comment on these questions in
the context of the information provided elsewhere on these issues. In
providing comments to these eleven questions, we ask that commenters
provide information both directly responsive to the individual question
and further to the relevance of the question in determining the
appropriate emission standard for diesel locomotives. For example,
question 1 lists a wide range of conditions for catalyst systems on a
diesel locomotive. In that context, EPA also invites comment on the
following questions.
? How do the shock loading, vibration loading, soot
exposure, and temperature exposure conditions listed in Question 1
compare to conditions faced by other applications of Zeolite-type urea
SCR systems that are either under development or that have been
developed for on-highway diesel, nonroad diesel, marine and stationary
gas turbine applications?
? Question 1 asserts that a locomotive catalyst design would
directly expose catalyst substrates to rain water, icing, water spray
and condensed frozen or liquid water during 20% of its life. Are there
catalyst packaging and installation issues that would necessitate any
direct exposure of catalyst substrates to weather?
? Question 1 implies that a locomotive catalyst design would
directly expose catalyst substrates to salt fogs consisting of 5 < plus-
minus> 1% salt concentration by weight with fallout rate between
0.00625 and 0.0375 ml/cm\2\/hr. What salt concentrations in salt fogs
and what fallout rates have SCR systems applied to ocean-going vessels
been exposed to? How would the systems designs, exposures and impacts
be similar to or different from locomotive applications? Are there
unique characteristics of locomotive catalyst installations that would
increase their exposure to salt fog relative to other applications
operated near or in ocean environments? What direct experiences have
ocean-going vessels had regarding the durability of their catalytic
emission control systems?
? Question 1 implies that locomotive catalyst systems must
withstand exposure to sand ingested by the engine at a rate of up to 50
pounds per hour at notch 8. The question also implies that locomotive
catalyst substrates must withstand exposure to a combination of red
china clay and silicon flour at a rate of up to one-quarter ton per
hour at notch 8. Are these appropriate metrics that reasonably take
into consideration the design of the locomotive air-intake and
filtration system and the ability of the engine and turbocharger
systems to withstand such extreme exposure to ingestion of abrasive
materials? Are tests replicating this condition routinely

[[Page 15985]]

conducted to demonstrate the durability of the engine and turbocharger
systems and emissions compliance following such high rates of engine
ingestion of abrasive materials?
? Questions 2 and 3 imply that greater than 45% DOC
oxidation efficiency is required to maintain Zeolite SCR catalyst
efficiency at greater than 94% NO_X efficiency, and that 94%
NO_X efficiency is required to meet the proposed Tier 4
NO_X standard. Is greater than 45% oxidation efficiency for
an upstream DOC necessary for locomotives to meet the 1.3 g/bhp-hr
NO_X standard over the range of exhaust temperature
encountered by locomotives over the line-haul duty cycle when using a
Zeolite-based SCR system? Is 94% NO_X efficiency from the
current Tier 2 locomotive baseline even necessary to achieve 1.3 g/bhp-
hr NO_X emissions when using a Zeolite SCR catalyst system
over the line-haul duty-cycle?
? What level of ammonia slip is achievable from modern urea-
SCR systems using closed-loop feedback control? Is 5 ppm an appropriate
level to set for maximum ammonia slip under any conditions?
? Is 5% of point the limit of zirconia-NO_X sensor
accuracy? Does NO_X sensor accuracy currently limit
NO_X conversion efficiency of feedback controlled SCR
systems, and if so by how much? What level of NO_X conversion
efficiency using a Zeolite-based SCR when not kinetically limited is
achievable using current feedback control systems using of zirconia-
NO_X sensors? What level of NO_X conversion
efficiency can be expected taking into consideration projected
NO_X sensor and feedback control system development over the
next ten to fifteen years?
Comments submitted should provide detailed technical information
and data to the extent possible. The EPA solicits comment on the extent
to which any factor may impact the ability to achieve the proposed
standard and if the proposed standard cannot be achieved in the
commenter's view, what standard can be achieved.

E. What Are EPA's Plans for Diesel Marine Engines on Large Ocean-Going
Vessels?

Today's proposal covers marine diesel engines up to 30 l/cyl
displacement installed on vessels flagged or registered in the U.S.
There are two additional significant sources of air pollution from
diesel marine engines which are not covered by today's proposal: first,
marine diesel engines of any size (Category 1, 2 or 3) installed on
foreign-flagged vessels; and second, marine diesel engines at or above
30 l/cyl displacement (Category 3) installed on U.S. flagged vessels.
The largest environmental concern for these types of engines are the
large, ocean-going marine vessels (OGV), which are typically larger
than 2,000 gross tons and involved primarily in international commerce.
Ocean-going marine vessels typically are powered by one or more
Category 3 diesel engines for propulsion of the vessel, and they
typically also have several Category 2 engines to provide auxiliary
power. Engines on OGV are predominately fueled by residual fuel (often
called ``heavy fuel oil''), which is a by-product of distilling crude
oil to produce lighter petroleum products such as gasoline, distillate
diesel fuel, and kerosene and has a high sulfur content, up to 45,000
ppm.\120\ Ocean-going vessels are a significant contributor to air
pollution in the United States, in particular in coastal areas and
ports. Current projections indicate that on a national level, OGVs
flagged in the U.S. and other countries will contribute about 21
percent of mobile source PM, 12 percent NO_X and 76 percent
of SO_X in the year 2030. These contributions can be much
higher in some coastal and port areas. However, recent inventory
estimates performed for the California Air Resources Board and the
Commission for Environmental Cooperation in North America suggest that
we are significantly underestimating the emissions for C3 engines, by
as much as a factor of 2 or 3.\121\
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\120\ Residual fuel also possesses a high viscosity and density,
which makes it harder to handle and use of this fuel requires
special equipment such as heaters, centrifuges, and purifiers. It
typically also has a high ash, and nitrogen content compared to
distillate diesel fuels. It is not produced to a set of narrow
specifications, and so fuel parameters can be highly variable.
\121\ Corbett, J.J., et al. Estimation, Validation, and
Forecasts of Regional Commercial Marine Vessel Inventories, Tasks 1
and 2: Baseline Inventory and Ports Comparison, Final Report, dated
3 May 2006. Prepared for the California Air Resources Board, the
Californian Environmental Protection Agency and the Commission for
Environmental Cooperation in North America. ARB contract 04-346, CEC
Contract 113.11. A copy of this document can be found at
http://www.arb.ca.gov/research/seca/jctask12.pdf.

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EPA has a number of activities underway which hold promise for
reducing air pollution from OGVs. These include: a future rulemaking
action on C3 engine standards; negotiations underway at the
International Maritime Organization to establish a new set of
environmentally protective international emission standards for OGVs;
studies to assess the feasibility of establishing one or more
SO_X Emission Control Areas adjacent to North America to
reduce SO_X and particulate matter from OGVs; and voluntary
actions through our Clean Ports USA program.
(1) Future C3 Marine Rule
In 2003 we issued a final rule for new C3 engines installed on U.S.
flagged vessels. That final action established NO_X limits
for new C3 engines which are equal to the current international
NO_X standards for C3 engines established through Annex VI of
the International Convention for the Prevention of Pollution from Ships
(MARPOL 73/78). The MARPOL standards are based on the capabilities of
emission control technologies from the early 1990s, and are
significantly higher then emission standards for any other mobile
source in the United States. In the 2003 final rule, we identified the
technical challenges associated with the application of after-treatment
technologies to these engines and vessels, but committed to revisiting
the issue of the appropriate long-term emission standards for C3 marine
engines, both those which are on vessels flagged in the U.S. and those
which are installed on foreign flagged vessels. In revisiting the
standards we indicated that we would consider the state of technology
that may permit deeper emission reductions and the status of
international action for more stringent standards. We committed to a
final Agency action by April 27, 2007.
In 2003, we believed the next round of emission standard
discussions at the IMO would be well underway, if not concluded, by
April of 2006. In 2003, we also believed the IMO deliberations would be
one of the avenues to explore improvements in emission control
technology for C3 engines and ocean-going vessels, and would provide
valuable technical input for EPA's C3 rulemaking.
Despite efforts by the United States Government at IMO,
deliberations regarding future emission standards for OGV did not begin
until April 2006. The current round of negotiations at IMO is expected
to continue through 2007. The discussions thus far at IMO have yielded
new technical information which EPA will be able to make use of in our
future C3 rulemaking. We expect to issue a revised schedule for the C3
rule in the next few months as well as solicit comments on the
appropriate technologies, standards, and lead time EPA should consider
for C3 standards.
(2) International Standards Deliberation at IMO
With respect to the discussions currently underway at the IMO, the
United States Government is actively

[[Page 15986]]

engaged in the negotiation of a new set of international standards for
Annex VI to the International Convention for the Prevention of
Pollution from Ships (MARPOL Annex VI). Since the current Annex VI
NO_X limits have entered into effect, and in the time frame
since EPA issued our 2003 rule, improvements in both in-cylinder and
external emission control technologies have been demonstrated, both in
the laboratory and on-board OGVs. These technologies offer the
potential to substantially reduce NO_X emissions from OGVs.
In addition, the use of lower sulfur residual or distillate fuels and/
or the use of SO_X scrubbing technologies offer the potential
to substantially reduce PM and SO_X emissions from OGVs. We
believe the member states of the IMO, including the United States, have
a unique opportunity to establish appropriate long-term standards to
address air pollution from OGVs.
The current discussions for the next tier of engine emission
standards at IMO also provide an opportunity to apply emission
reduction technologies to existing vessels. EPA is a strong supporter
of reducing pollution of existing vessels through mandatory rebuild/
retrofit requirements and we will continue to pursue this objective at
the IMO.
(3) SO_X Emission Control Areas
The existing international agreements adopted by the IMO provide
the opportunity for signatories to Annex VI of the International
Convention for the Prevention of Pollution from Ships to propose the
designation of one or more SO_X Emission Control Areas
(SECA). When operating in a SECA, all OGVs must either use fuel with a
maximum sulfur content of 15,000 ppm or use emission control technology
such that the vessel meets a SO_X limit of 6 g/kW-hr (a value
deemed equivalent to 15,000 ppm sulfur). This represents only
approximately a 45 percent reduction in SO_X emissions
compared to the world-wide fuel sulfur average for heavy-fuel oil of
about 27,000 ppm. EPA is currently performing environmental impact and
economic analyses that will assist the federal government in making a
determination whether the U.S. Government should consider a proposal
designating a SECA to one or more areas adjacent to North America. We
are working closely with the Canadian Government Canada) on these
efforts, and we also intend to coordinate our actions with Mexico. This
could allow for the inclusion of additional coastal areas within SECAs
for North American. It must be noted that the United States has not yet
ratified Annex VI and any decision regarding whether the United States
will pursue the designation of a SECA will be influenced by where the
United States stands with respect to ratification of MARPOL Annex VI.
(4) Clean Ports USA
As part of EPA's National Clean Diesel Campaign, Clean Ports USA is
an incentive-based, public-private partnership designed to reduce
emissions from existing diesel engines and vessels at ports. The Clean
Ports USA team works to bring together partners and build coalitions to
identify and develop cost-effective diesel emission reduction projects
that address the key issues affecting ports today. EPA provides
technical support in verifying the effectiveness of retrofit
technology, to ensure through rigorous testing that the emissions
reductions promised by vendors are in fact achieved in the field.
Clean Ports USA is providing incentives to port authorities,
terminal operators, cargo interests, trucking fleets, and maritime
fleet owners to:
? Retrofit and replace older diesel engines with verified
technologies such as diesel oxidation catalysts (DOCs), diesel
particulate filters (DPFs).
? Use cleaner fuels (ultra-low sulfur diesel fuel, emulsions).
? Increase operational efficiency, including environmental
management systems, logistics, and appointment systems.
? Reduce engine idling.
? Replace older engines with new, cleaner engines.
Additional information is available on the Clean Ports USA Web site
at http://www.epa.gov/cleandiesel/ports.

IV. Certification and Compliance Program

This section describes the regulatory changes proposed for the
locomotive and marine compliance programs. The most obvious change is
that the proposed regulations have been written in plain language. They
are structured to contain the provisions that are specific to
locomotives in a new proposed part 1033 and contain the provisions that
are specific to marine engines and vessels in a new proposed part 1042.
We also propose to apply the general provisions of existing parts 1065
and 1068.\122\ The proposed plain language regulations, however, are
not intended to significantly change the compliance program, except as
specifically noted in today's notice (and we are not reopening for
comment the substance of any part of the program that remains unchanged
substantively). As proposed, these plain language regulations would
supersede the regulations in part 92 and 94 (for Categories 1 and 2) as
early as the 2008 model year. See section III for the starting dates
for different engines. The changes from the existing programs are
described below along with other notable aspects of the compliance
program. Note: The term manufacturer is used in this section to include
locomotive and marine manufacturers and locomotive remanufacturers. It
would also include marine remanufacturers if we finalize remanufacture
standards.
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\122\ In a separate rulemaking, which has been submitted to the
Office of Management and Budget (OMB) for review, we will be
proposing modifications to the existing provisions of 40 CFR part
1068. We have placed into the docket for this current proposal, a
copy of the draft part 1068 regulatory language that was submitted
to OMB. Readers interested in the compliance provisions that would
apply to locomotives and marine diesel engines should also read the
actual regulatory changes that will be proposed in that upcoming rulemaking.
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A. Issues Common to Locomotives and Marine

For many aspects of compliance, we are proposing similar provisions
for marine engines and locomotives, which are discussed in this
section. Also included in this section are issues which are similar,
but where we are proposing different provisions. The other compliance
issues are discussed in sections IV. B. (for locomotives) and IV. C.
(for marine).
(1) Modified Test Procedures
(a) Incorporation of Part 1065 Test Procedures for Locomotive and
Marine Diesel Engines
As part of our initiative to update the content, organization and
writing style of our regulations, we are revising our test procedures.
We have grouped all of our engine dynamometer and field testing test
procedures into one part entitled, ``Part 1065: Test Procedures.'' For
each engine or vehicle sector for which we have recently promulgated
standards (such as land-based nonroad diesel engines or recreational
vehicles), we identified an individual part as the standard-setting
part for that sector. These standard-setting parts then refer to one
common set of test procedures in part 1065. We intend in this proposal
to continue this process of having all our engine programs refer to a
common set of procedures by applying part 1065 to all locomotive and
marine diesel engines.
In the past, each engine or vehicle sector had its own set of
testing procedures. There are many similarities in test procedures
across the various sectors. However, as we introduced new regulations
for individual sectors, the

[[Continued on page 15987]]

Notices For
2007
2006
2005
2004
2003
2002
2001
2000
1999
1998
1997
1996
1995
1994

Control of Emissions of Air Pollution From Locomotive Engines and Marine Compression-Ignition Engines Less Than 30 Liters per Cylinder

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