[Federal Register: January 18, 2008 (Volume 73, Number 13)]
[Notices]
[Page 3464-3467]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]
[DOCID:fr18ja08-52]
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ENVIRONMENTAL PROTECTION AGENCY
[CAXXX-NOA; FRL-8517-9]
Official Release of EMFAC2007 Motor Vehicle Emission Factor Model
for Use in the State of California
AGENCY: Environmental Protection Agency (EPA).
ACTION: Notice of Availability.
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SUMMARY: EPA is approving and announcing the availability of the latest
version of the California EMFAC model for use in state implementation
plan (SIP) development in California. EMFAC2007 is the latest update to
the EMFAC model for use by California state and local governments to
meet Clean Air Act (CAA) requirements. The new model, which is based on
new and improved data, calculates air pollution emission factors for
passenger cars, trucks, motorcycles, motor homes and buses. Today's
notice also sets the date after which EMFAC2007 is required to be used
statewide in all new regional emissions analyses and carbon monoxide
(CO) hot-spot analyses for transportation conformity determinations in
California. EPA also intends to approve EMFAC2007 in the future for
particulate matter (PM10 and PM2.5) hot-spot
analyses in California, once EPA issues quantitative hot-spot modeling
guidance for such analyses. Since the EMFAC model is used only in
California, EPA's approval of the model does not affect MOBILE model
users in other states.
DATES: This determination is effective January 18, 2008. EMFAC2007 must
be used for all new regional emissions
[[Page 3465]]
analyses and CO hot-spot analyses that are started on or after April
18, 2008.
FOR FURTHER INFORMATION CONTACT: Karina O'Connor,
oconnor.karina@epa.gov, (775) 833-1276, Air Planning Office (AIR-2),
Air Division, U.S. EPA, Region 9, 75 Hawthorne Street, San Francisco,
California, 94105-3901. For questions regarding the future development
of quantitative PM10 and PM2.5 hot-spot modeling
guidance, contact Meg Patulski, patulski.meg@epa.gov, (734) 214-4842,
Transportation and Regional Programs Division, U.S. EPA's Office of
Transportation and Air Quality, 2000 Traverwood Road, Ann Arbor, MI
48105.
SUPPLEMENTARY INFORMATION: Copies of the official version of the
EMFAC2007 model are available on the California Air Resources Board
(CARB) Web site: http://www.arb.ca.gov/msei/onroad/latest_version.htm
(model, technical support documents, etc).
I. Background
A. What Is the EMFAC Model?
The EMFAC model (short for EMission FACtor) is a computer model
that can estimate emission rates for on-road mobile sources (``motor
vehicles'') for calendar years from 1970 to 2040 operating in
California. Pollutant emissions for hydrocarbons (HC), CO, nitrogen
oxides (NOX), PM10, PM2.5, lead, and
sulfur oxides are output from the model. Emissions are calculated for
thirteen different vehicles classes comprised of passenger cars,
various types of trucks and buses, motorcycles, and motor homes. The
EMFAC2007 model is operated with a user-friendly graphical user
interface (GUI) which facilitates data input and allows the development
of alternative emissions scenarios through a What If Scenarios (WIS)
generator. The WIS interface can be used to incorporate updated vehicle
data, adjust ambient conditions or make changes to potential emission
control programs in a specific area.
EMFAC is used to calculate current and future inventories of motor
vehicle emissions at the state, air district, air basin, or county
level. EMFAC contains default vehicle activity data, and the option of
modifying that data, so it can be used to estimate a motor vehicle
emission inventory in tons/day for a specific year, month, or season,
and as a function of ambient temperature, relative humidity, vehicle
population, mileage accrual, miles of travel and speeds. Thus the model
can be used to make decisions about air pollution policies and programs
at the local or state level. Inventories based on EMFAC are also used
to meet the federal CAA's SIP and transportation conformity
requirements. Transportation conformity is required under CAA section
176(c) to ensure that federally supported transportation plans,
transportation improvement programs (TIPs), and highway and transit
projects are consistent with (``conform to'') the purpose of the SIP.
B. What Versions of EMFAC Are Currently in Use in California?
Most SIPs in California were developed using EMFAC2002 (released by
CARB in October 2002) or EMFAC2000 (released by CARB in May 2000). EPA
approved use of EMFAC2000 in January 2002 only for the San Francisco
Bay Area (67 FR 1464). EPA approved EMFAC2002 in April 2003 (68 FR
15720) for all areas in California.
EMFAC2002 was considered a major update to previous versions of
EMFAC and most SIPs in California were updated with EMFAC2002 in the
2003-2006 timeframe. EMFAC2002 included significant changes to its
model interface, new data and methodologies regarding calculation of
motor vehicle emissions, revision to implementation data for control
measures, and corrections to technical errors mentioned in our prior
approval of EMFAC2000. Areas with SIP motor vehicle emissions budgets
developed using earlier versions of EMFAC were required to use
EMFAC2002 for regional conformity analyses at the end of the grace
period provided by 40 CFR 93.111(b).
C. Why Is EPA Announcing Its Approval of the EMFAC Model?
CAA section 172(c)(3) and 40 CFR 51.112(a)(1) require that SIP
inventories be based on the most current, accurate, and applicable
models that are available at the time the SIP is developed. CAA section
176(c)(1) requires that the latest emissions estimates be used in
conformity analyses. EPA approves models that fulfill these
requirements.
Under 40 CFR 93.111(a), EPA must approve new versions of EMFAC for
SIP purposes before they can be used in transportation conformity
analyses. In an April 18, 2007 letter, CARB requested that EPA approve
EMFAC2007 for use in developing SIPs and in determining conformity in
California. EMFAC2007 is a significant change from previous EMFAC
models and is capable of calculating motor vehicle emissions for all
California areas. EMFAC2007 is being approved as the latest emissions
model for statewide use in SIP development. Since the EMFAC model is
only used in California, EPA's statewide approval of the model does not
affect MOBILE emissions factor model users in other states.
D. Why Have Transportation Agencies Stopped Using EMFAC2002 for
Regional Conformity Emissions Analyses?
On February 1, 2007, the Federal Highway Administration (FHWA) sent
a letter to all of the Metropolitan Planning Organizations in
California and Caltrans Districts indicating that, after August 1,
2007, they would not be able to start any new transportation conformity
determinations that require a new regional emissions analysis, unless
the analysis incorporates more recent vehicle data consistent with the
latest planning assumptions requirements in the conformity rule (40 CFR
93.110). The letter indicated that updated vehicle data was available
in EMFAC2007, which was released to the public in November 2006. The
letter indicated that FHWA, the Federal Transit Administration (FTA),
and EPA were providing agencies with a 6-month transition period,
beginning on February 1, 2007 before the new vehicle fleet data was
required in conformity determinations. Consistent with the EPA/USDOT
January 18, 2001, guidance on latest planning assumptions and EPA's
July 1, 2004 final rule (69 FR 40052-40056), new vehicle registration
data must be used when it is available at the start of new conformity
analyses. Since newer vehicle data was available but was not included
in the older version of EMFAC, EMFAC2002 has not been used in any new
regional emissions analyses that were started since August 1, 2007.
II. EPA Action
A. What Version of EMFAC Is EPA Approving?
In this notice, EPA is approving and announcing that EMFAC2007 is
available to use in statewide California SIP development and for
regional emissions analyses and carbon monoxide (CO) hot-spot analyses
for transportation conformity analyses. EMFAC2007 was developed by CARB
and transmitted for approval to EPA on April 18, 2007.
On January 28, 2003, CARB also transmitted a methodology
(``Recommended Methods for Use of EMFAC2002 to Develop Motor Vehicle
Emission Budgets and Assess Conformity'') to adjust vehicle activity
data used by EMFAC2007 when updated data is available. EPA previously
approved this CARB
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methodology on April 1, 2003 (68 FR 15720, at 15721) for use with
EMFAC2002, since the transportation conformity rule (40 CFR 93.110)
requires areas to use the latest information for estimating vehicle
activity. With EMFAC2007, CARB has not made any changes to the
methodology to adjust vehicle activity data, and therefore the existing
approved methodology will continue to be approved with no change.
However, the methodology has been included in the updates to Chapter 8
of the EMFAC user's guide. Therefore, CARB's methodology should
continue to be used to update vehicle activity data in EMFAC2007, as
described in the EMFAC user's guide.
B. What Analyses Can EMFAC2007 Be Used For?
EPA is approving the model to estimate regional emissions of HC,
CO, NOX, PM10, PM2.5, lead, and sulfur
oxides. However, EMFAC2007 will only be used in transportation
conformity for pollutants and precursors that affect transportation
emissions, e.g., HC, NOX, CO, PM10 and
PM2.5.
EPA is also approving EMFAC2007 to estimate CO emissions for hot-
spot analyses involving individual transportation projects. A hot-spot
analysis is defined in 40 CFR 93.101 as an estimation of likely future
localized pollutant concentrations resulting from a new transportation
project and a comparison of those concentrations to the relevant air
quality standard. This analysis is conducted on a smaller scale, e.g.,
for a congested roadway intersection.
EPA also notes that today's approval action does not impact what
methodology is required for calculating re-entrained road dust or
ammonia emissions for regional PM10 and PM2.5 SIP
and transportation conformity analyses. EMFAC2007's PM10 and
PM2.5 estimates do not include such emissions. When
applicable, PM10 and PM2.5 nonattainment and
maintenance areas are required to use EPA's AP-42 road dust method for
calculating road dust emissions, unless a local method is approved by
EPA.\1\ EMFAC2007 does not estimate ammonia emissions; air quality and
transportation agencies should contact the regional office if ammonia
emission estimates are needed.
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\1\ For further information, see EPA's August 2, 2007 memorandum
entitled, ``Policy Guidance on the Use of the November 1, 2006,
Update to AP-42 for Re-entrained Road Dust for SIP Development and
Transportation Conformity.''
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C. Is EMFAC2007 Being Approved for PM10 and PM2.5 Hot-spot Analyses At
This Time?
On March 10, 2006, EPA published a final rule that established the
transportation conformity procedures for analyzing PM10 and
PM2.5 hot-spot impacts of new projects involving significant
levels of on-road diesel traffic (71 FR 12468). Quantitative
PM10 and PM2.5 hot-spot analyses have not yet
been required for the projects of local air quality concern described
in 40 CFR 93.123(b)(1) due to the need to develop EPA modeling guidance
and appropriate methods (71 FR at 12498-12502). Section 93.123(b)(4) of
the conformity rule states that the requirements for quantitative
PM10 and PM2.5 hot-spot analyses will not take
effect until EPA releases modeling guidance and announces in the
Federal Register that these requirements are in effect. At present,
project sponsors are currently following EPA and FHWA's qualitative
hot-spot modeling guidance for conformity determinations involving
projects of local air quality concern.\2\ EMFAC2007 is capable of
assessing project-level emissions for PM10 and
PM2.5 hot-spot analyses, but as described in the March 2006
final rule and 40 CFR 93.123(b)(4), EPA believes that quantitative PM
hot-spot modeling guidance is also necessary before quantitative PM
hot-spot analyses can be required. Therefore, since such guidance is
currently not available, EPA is not approving EMFAC2007 for
PM10 and PM2.5 hot-spot conformity analyses at
this time.
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\2\ ``Transportation Conformity Guidance for Qualitative Hot-
Spot Analyses in PM2.5 and PM10 Nonattainment
and Maintenance Areas'' jointly published by EPA and FHWA in March
2006.
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Over the next year, EPA intends to develop quantitative
PM10 and PM2.5 hot-spot modeling guidance, which
will contain information on how to use EMFAC2007 and how to apply the
appropriate dispersion models for such analyses in California. EPA will
announce the availability of the guidance and approval of EMFAC2007 for
quantitative PM hot-spot analyses when the guidance is completed for
California. EPA will consult with FHWA, FTA, CARB, the California state
department of transportation (Caltrans), other stakeholders, and the
public in the development of this guidance, as described in the March
2006 final rule. Please see the FOR FURTHER INFORMATION CONTACT section
if you have questions regarding the development of conformity guidance
for quantitative PM10 and PM2.5 hot-spot analyses
in California.
D. Why Does EPA Consider EMFAC2007 as a Major Update to EMFAC?
EMFAC2007 includes new data and methodologies regarding calculation
of motor vehicle emissions and revisions to implementation data for
control measures. EMFAC2007 includes updated data supporting new
emission factors and speed correction factors for estimating emissions
from heavy-heavy duty diesel trucks. The model includes modifications
to the algorithms for inspection and maintenance as well as corrections
for heavy-duty truck gas cap benefits from the inspection and
maintenance program. Impacts of ethanol permeation and updates to fuel
correction factors are included as well as revisions to particulate
brake wear emissions. EMFAC2007 incorporates new temperature and
humidity profiles. In addition to these changes, which impact emission
factors for each area in California, EMFAC incorporates new mileage
accrual rates and speed distributions, a redistribution of heavy-duty
diesel truck vehicle miles traveled (VMT) and updated VMT for all
vehicle classes. CARB's web site describes these and other model
changes at: http://www.arb.ca.gov/msei/workshops.htm#work20061115.
E. How Were Stakeholders and the Public Involved in the EMFAC
Development Process?
Since 2005, CARB has held a series of public workshops to discuss
proposed model updates and receive comments on interim versions of the
new model. Three workshops were held to solicit input from stakeholders
and the public in March of 2005. Then, in workshops held on September
11 and November 15 and 16, 2006, CARB described the latest EMFAC
changes under consideration and sought public input. Those changes are
reflected in the final EMFAC2007 model submitted to EPA in April 2007.
One additional public information briefing was held on December 15,
2006, to share the emissions estimates resulting from use of the final
model with updated travel activity, as well as plans for transmittal of
EMFAC2007 to U.S. EPA. CARB has also discussed both the model and the
impact of the changes to emission totals for the state at the
workshops.
CARB also released a series of technical memos that describe each
update to the model, and public presentations that summarize the
changes from earlier versions of the model. The technical memos are
available on CARB's Web site at: http://www.arb.ca.gov/msei/supportdocs.htm.
Each memo describes the model update,
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the reason for the change, how the change was incorporated into the
EMFAC model, and the resulting emissions impact. All presentations from
the public workshops are available on the CARB Web site at: http://www.arb.ca.gov/msei/workshops.htm#work200612.
These presentations
summarize the major changes to the EMFAC model and contain tables
showing the impacts of the changes both statewide and by county for HC,
CO, NOX, PM10, and PM2.5.
F. Will a Transportation Conformity Grace Period Be Set by This
Approval?
Yes. The transportation conformity rule (40 CFR part 93.111)
requires that conformity analyses be based on the latest motor vehicle
emissions model approved by EPA for SIP purposes for a state or area.
Section 176(c)(1) of the CAA states that ``* * * [t]he determination of
conformity shall be based on the most recent estimates of emissions,
and such estimates shall be determined from the most recent population,
employment, travel, and congestion estimates. * * *'' When EPA approves
a new emissions model such as EMFAC2007, a grace period is established
before the model is required for conformity analyses. However, areas
have the option of using the new model prior to the end of the grace
period. The conformity rule provides for a grace period for new
emissions models of between 3 to 24 months. In consultation with FHWA
and FTA, EPA considers many factors in establishing the length of the
grace period, including the degree of change in emissions models and
the effects of the new model on the transportation planning process (40
CFR 93.111).
Upon consideration of all of these factors, EPA is establishing a
3-month grace period before EMFAC2007 is required for the following
conformity analyses:
All new HC, NOX, PM10,
PM2.5 and CO regional emissions analyses (e.g., supporting
transportation plan and TIP conformity determinations); and
All new CO hot-spot analyses supporting project-level
conformity determinations.
The grace period begins today and ends on April 18, 2008. As
discussed earlier in the notice, the last version of EMFAC (EMFAC2002)
is no longer used in California for new regional emissions analyses for
transportation plan and TIP conformity determinations. Therefore it is
appropriate to set a short grace period since all areas in California
will need to use EMFAC2007 to begin any new regional conformity
analyses. A longer grace period would provide no practical benefit for
transportation plan and TIP conformity determinations, since older
EMFAC models cannot be used in new regional analyses due to the latest
planning assumptions requirements in the conformity rule (40 CFR
93.110).
When the grace period ends on April 18, 2008, EMFAC2007 will become
the only approved motor vehicle emissions model for all new regional
and CO hot-spot transportation conformity analyses across California.
In general, this means that all new HC, NOX,
PM10, PM2.5, and CO regional conformity analyses
and CO hot-spot analyses started after the end of the 3-month grace
period must be based on EMFAC2007, even if the SIP is based on an
earlier version of the EMFAC model.
G. Can Areas Use Any Other Models During the Grace Period?
Yes, in limited cases. CO hot-spot analyses for project-level
conformity determinations can be based on EMFAC2002 if the analysis was
begun before the end of the grace period, started before August 1, 2007
and if the final environmental document for the project is issued no
more than three years after the issuance of the draft environmental
document (see 40 CFR 93.111(c)). The interagency consultation process
should be used if it is unclear whether an EMFAC2002 based analysis is
covered by the circumstances described above.
H. Future Updates to EMFAC
On January 31, 2006, CARB submitted a letter to EPA and to the
California Division of the FHWA indicating the State's intention to
update future revisions to EMFAC. These EMFAC updates would reflect,
among other new information, updated vehicle fleet data every three
years. In California, Metropolitan Planning Organizations and Air
Districts have not been able to update vehicle fleet data embedded into
EMFAC. The EPA/USDOT January 18, 2001, guidance on latest planning
assumptions and EPA's July 2004 final rule, indicate that new vehicle
registration data must be used when it is available prior to the start
of new conformity analyses and that states should update the data at
least every five years. The State reaffirmed their commitment to
keeping the latest planning assumptions included in EMFAC updated on a
three year cycle in the April 18, 2007 EMFAC submittal letter. The next
update to the planning assumptions in EMFAC is expected in 2010, which
would most likely also include updates to the emissions factors of the
model as well.
III. Summary of EPA Actions
EPA is approving EMFAC2007 as submitted by CARB on April 18, 2007
with the following limitations and conditions:
(1) The approval is limited to California.
(2) The approval is Statewide and applies to estimation of
emissions of hydrocarbon, carbon monoxide, nitrogen oxides, particulate
matter (PM10 and PM2.5), lead, and sulfur oxides.
However, EMFAC2007 will only be used in transportation conformity
analyses for pollutants and precursors that affect regional on-road
mobile emissions and are applicable in a given nonattainment or
maintenance area. EPA is also approving EMFAC2007 to estimate hot-spot
emissions for carbon monoxide conformity analyses.
(3) A 3-month statewide transportation conformity grace period will
be established beginning January 18, 2008 and ending April 18, 2008 for
the transportation conformity uses described in (2) above.
Dated: January 10, 2008.
Jane Diamond,
Acting Regional Administrator, Region IX.
[FR Doc. E8-876 Filed 1-17-08; 8:45 am]
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