[Federal Register Volume 80, Number 239 (Monday, December 14, 2015)]
[Pages 77337-77340]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2015-31307]



[EPA-R09-OAR-2015-0779; FRL-9940-06-Region 9]

Official Release of EMFAC2014 Motor Vehicle Emission Factor Model 
for Use in the State of California

AGENCY: Environmental Protection Agency (EPA).

ACTION: Notice of availability.


SUMMARY: The Environmental Protection Agency (EPA) is approving and 
announcing the availability of the latest version of the California 
EMFAC (short for EMission FACtor) model for use in state implementation 
plan (SIP) development and transportation conformity in California. 
EMFAC2014 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 emissions factors for passenger cars, trucks, motorcycles, 
motor homes and buses. Today's notice also sets the date after which 
EMFAC2014, rather than EMFAC2011, must be used to satisfy the 
requirement that conformity determinations be based on the latest 
emissions model available. This requirement can be met by using the 
most current version of the motor vehicle emissions model approved by 
the EPA. Since the EMFAC model is used only in California, the EPA's 
approval and the announcement of the availability of the model does not 
affect the applicability of the Motor Vehicle Emissions Simulator 
(MOVES) model for users in other states.

DATES: The EPA's approval of the EMFAC2014 emissions model for SIP and 
conformity purposes is effective December 14, 2015. EMFAC2014 must be 
used as described in this Notice for all new regional emissions 
analyses and carbon monoxide (CO) and particulate matter 
(PM10 and PM2.5) hot-spot analyses for 
transportation conformity purposes that are started on or after 
December 14, 2017.

[email protected], (775) 434-8176, Air Planning Office (AIR-2), 
Air Division, U.S. EPA, Region 9, 75 Hawthorne Street, San Francisco, 
California 94105-3901.

SUPPLEMENTARY INFORMATION: Copies of the official version of the 
EMFAC2014 model, including technical support documents, are available 
on the California Air Resources Board (CARB) Web site: http://www.arb.ca.gov/msei/categories.htm#onroad_motor_vehicles. Throughout 
this document, ``we,'' ``us'' and ``our'' refer to EPA.

I. Background

A. What is the EMFAC model?

    The EMFAC model is a computer model that can estimate emission 
rates for on-road mobile sources (``motor vehicles'') for calendar 
years from 2000 to 2050 operating in California. Pollutant emissions 
for hydrocarbons (HC), CO, nitrogen oxides (NOX), 
PM10, PM2.5, lead, carbon dioxide 
(CO2), and sulfur oxides are output from the model. 
Emissions are calculated for fifty-one different vehicle classes 
composed of passenger cars, various types of trucks and buses, 
motorcycles, and motor homes.
    EMFAC is used to calculate current and future inventories of motor 
vehicle emissions at the state, air district, air basin, county, or 
project level. EMFAC contains default vehicle activity data, and the 
option of modifying that data, so it can be used to estimate a motor 
vehicle emissions 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. Conformity to a SIP means that 
a transportation activity will not cause or contribute to new air 
quality violations, worsen existing violations, or delay timely 
attainment of the national ambient air quality standards (NAAQS) or 
interim milestones. The EPA's transportation conformity regulations (40 
CFR parts 51.390 and 93) describe how federally funded and approved 
highway and transit projects meet these statutory requirements. EMFAC 
is used statewide in all regional emissions analyses and CO, 
PM10 and PM2.5 hot-spot analyses for 
transportation conformity determinations in California.

B. What versions of EMFAC are currently in use in California?

    Most SIPs in California were developed using EMFAC2011 (released by 
CARB in September 2011) or EMFAC2007 (released by CARB in October 
2007). The EPA approved and announced the availability of EMFAC2011 on 
March 16, 2013 (78 FR 14533) and approved and announced the 
availability of EMFAC2007 on January 18, 2008 (73 FR 3464) for all 
nonattainment and maintenance areas in California.
    EMFAC2011 was considered a major update to previous versions of 
EMFAC and most SIPs in California were updated with EMFAC2011 in the 
2012-2014 timeframe. EMFAC2011 included a new model structure, new data 
and methodologies regarding calculation of motor vehicle emissions, and 
revisions to implementation data for control measures.

[[Page 77338]]

C. Why is the EPA announcing its approval of the EMFAC model?

    CAA section 172(c)(3) and 40 CFR 51.114(a) 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) and 40 CFR 93.111(a) require that the latest emissions 
estimates be used in conformity analyses. The EPA approves models that 
fulfill these requirements.
    Under 40 CFR 93.111(a), the EPA must approve new versions of EMFAC 
for SIP purposes before they can be used in transportation conformity 
analyses. In a May 21, 2015 letter, CARB requested that the EPA approve 
EMFAC2014 for use in developing SIPs and in determining conformity in 
California.\1\ EMFAC2014 is a significant change from previous EMFAC 
models with a new model user interface and is capable of calculating 
motor vehicle emissions for all California areas. EMFAC2014 is being 
approved as the latest emissions model for statewide use in SIP 
development and emissions analyses for conformity purposes. Since the 
EMFAC model is only used in California, the EPA's statewide approval of 
the model does not affect the applicability of the MOVES emissions 
factor model for users in other states.

    \1\ The EMFAC2014 model and supporting information is available 
for downloading at http://www.arb.ca.gov/msei/categories.htm#onroad_motor_vehicles. Technical documentation 
explaining the changes to the model and the technical foundations 
for the model is available at http://www.arb.ca.gov/msei/downloads/emfac2014/emfac2014-vol3-technical-documentation-052015.pdf .

II. EPA Action

A. What version of EMFAC is the EPA approving?

    In this notice, the EPA is approving and announcing that EMFAC2014 
is available to use in statewide California SIP development and for 
regional emissions analyses and CO, PM10 and 
PM2.5 hot-spot analyses for transportation conformity. 
EMFAC2014 was developed by CARB and transmitted for approval to the EPA 
on May 21, 2015.
    The EMFAC2014 model has been rewritten using Python and MySQL 
software into a new structure that will facilitate future model 
updates, and allow CARB to incorporate updated regulations and 
emissions data into the model and provide for a more simplified user 
experience. The four major modules of EMFAC2011: EMFAC-LDV, EMFAC-HD, 
EMFAC-SG and EMFAC-PL have been integrated into EMFAC2014, under one 
interface. The model is now operated in either the Emissions Mode or 
the Emissions Rate Mode for regional emissions analyses to access 
emission databases and vehicle activity data for the appropriate 
geographic subarea. EMFAC2014 Project-Level Assessment (EMFAC2014-PL) 
is triggered when EMFAC2014 is run under the Emissions Rate Mode. Using 
EMFAC2014-PL, emissions rates are estimated based on user-specified, 
project-specific conditions. A handbook for using EMFAC2014 at the 
project level is available from CARB at: http://www.arb.ca.gov/msei/downloads/emfac2014/emfac2014-vol2-pl-handbook-052015.pdf. EMFAC2014 
allows users to run one model for SIP inventories, regional emissions 
analyses and project analyses.

B. What analyses can EMFAC2014 be used for?

    The EPA is approving the model to estimate regional emissions of 
HC, CO, NOX, PM10, PM2.5, lead, and 
sulfur oxides.\2\ However, EMFAC2014 will only be used in 
transportation conformity for pollutants and precursors that are 
transportation-related emissions, e.g., HC, CO, NOX, 
PM10 and PM2.5.

    \2\ The EPA notes that EMFAC2014 can be used for CO2 
emissions analyses as well, but there are no SIP or transportation 
conformity requirements for greenhouse gases (GHGs). In addition, 
although SO2 is listed as a potential precursor for 
PM2.5 formation in 40 CFR 93.102(b)(2)(v), this precursor 
has not been considered significant for the on-road mobile sources 
covered by transportation conformity in California to date.

    The EPA is also approving EMFAC2014 to estimate CO, PM10 
and PM2.5 emissions for conformity 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 and a comparison of those concentrations to 
the relevant NAAQS. This analysis is conducted on a smaller scale than 
a nonattainment or maintenance area, e.g., for a congested roadway 
    The EPA also notes that this approval action does not impact what 
methodology is required for calculating re-entrained road dust for 
regional PM10 and PM2.5 SIPs and transportation 
conformity analyses. EMFAC2014'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 the EPA's AP-42 road dust method for 
calculating road dust emissions, unless a local method is approved in 
advance by the EPA.\3\ In addition, EMFAC2014 does not estimate ammonia 
emissions. Air quality and transportation agencies should contact the 
EPA Regional Office if ammonia emissions estimates are needed for SIPs 
or regional conformity emissions analyses.

    \3\ For further information, see the EPA's February 4, 2011 
Notice of Availability for the January 2011 AP-42 Method for 
Estimating Re-entrained Road Dust from Paved Roads (76 FR 6328). 
Also, for using AP-42 for unpaved roads, see the EPA's August 2, 
2007 memorandum, ``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.''

C. Why does the EPA consider EMFAC2014 to be a major update to EMFAC?

    EMFAC2014 includes significant changes to its model interface, new 
data and methodologies regarding calculation of motor vehicle emissions 
and revisions to implementation data for control measures. EMFAC2014 
includes updated data on car and truck activities, and emissions 
reductions associated with CARB's Advanced Clean Cars regulations,\4\ 
supporting new estimates of emissions from heavy-heavy duty diesel 
trucks and buses. Motor vehicle fleet age, vehicle types and vehicle 
population have also been updated based on 2000-2012 California 
Department of Motor Vehicle (DMV) data. Each of these changes impact 
emission factors for each area in California. The new model interface 
for EMFAC2014 will allow users to update the default VMT data and speed 
profiles by vehicle class for different future scenarios. CARB's Web 
site describes these and other model changes at: http://www.arb.ca.gov/msei/categories.htm#onroad_motor_vehicles.

    \4\ For further information, see EPA's January 9, 2013 waiver of 
preemption for the Advanced Clean Cars regulations at http://www.gpo.gov/fdsys/pkg/FR-2013-01-09/pdf/2013-00181.pdf.

D. How were stakeholders and the public involved in the EMFAC 
development process?

    Since 2013, CARB has held a series of public workshops to discuss 
emissions inventory updates and EMFAC updates and to receive comments 
on the resulting changes in the emissions inventory and models.\5\ CARB 
also conducted beta testing of interim versions of the model with air 
districts and Metropolitan Planning Organizations (MPOs). Stakeholders 
and other members of the public had the opportunity to request 
briefings with CARB staff and provide them with comments and 
suggestions to improve the model. The EPA was included in those 
discussions and our suggestions were incorporated into the material

[[Page 77339]]

available on the CARB EMFAC public Web site. CARB also developed and 
posted training modules for EMFAC2014 and supports a mobile source 
emissions inventory email listserv to announce updates and changes to 
the EMFAC supporting material.\6\

    \5\ See http://www.arb.ca.gov/msei/workshop-meetings.htm.
    \6\ To subscribe to CARB's listserv for Mobile Source Emission 
Inventory development, see ``Join our MSEI listserv'' at 

    CARB also made available to the public 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/downloads/emfac2014/emfac2014-vol4-comp-table-of-emfac-topics-052015.xlsx and at http://www.arb.ca.gov/msei/categories.htm#onroad_motor_vehicles. Specific changes incorporated 
into the EMFAC2014 model are also discussed in http://www.arb.ca.gov/msei/downloads/emfac2014/emfac2014-vol3-technical-documentation-052015.pdf. All presentations from the public workshops are available 
on the CARB Web site at: http://www.arb.ca.gov/msei/workshop-meetings.htm.

E. Does this Notice establish a transportation conformity grace period 
for the use of this model?

    Yes. The transportation conformity rule (40 CFR 93.111) requires 
that conformity determinations be based on the latest motor vehicle 
emissions model approved by the 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 the EPA approves and announces the availability of a new 
emissions model such as EMFAC2014, the EPA will consult with the U.S. 
Department of Transportation (DOT) to establish a grace period before 
the model is required for conformity analyses (40 CFR 93.111(b)). The 
conformity rule provides for a grace period for new emissions models of 
between 3 and 24 months after notice of availability is published in 
the Federal Register (40 CFR 93.111(b)(1)).
    The EPA articulated its intentions for establishing the length of a 
conformity grace period in the preamble to the 1993 transportation 
conformity rule (November 24, 1993, 58 FR 62211):

    EPA and DOT [the Department of Transportation] will consider 
extending the grace period if the effects of the new emissions model 
are so significant that previous SIP demonstrations of what emission 
levels are consistent with attainment would be substantially 
affected. In such cases, States should have an opportunity to revise 
their SIPs before MPOs must use the model's new emissions factors.

    In consultation with the Federal Highway Administration (FHWA) and 
the Federal Transit Administration (FTA), the EPA considers ``the 
degree of change in the model and the scope of re-planning likely to be 
necessary by MPOs in order to assure conformity'' in establishing the 
length of the grace period (40 CFR 93.111(b)(2)).
    Upon consideration of these factors, the EPA is establishing a two-
year grace period before EMFAC2014 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, PM10 and PM2.5 hot-spot 
analyses supporting project-level conformity determinations.
    The grace period begins on December 14, 2015 and ends on December 
14, 2017. Areas have the option of using the new model prior to the end 
of the grace period.
    As discussed earlier in the notice, EMFAC2014 incorporates 
significant changes to the model interface and procedures used to 
estimate both emissions for regional emissions analysis and hot-spot 
analyses for CO and PM. In addition to incorporating the new EMFAC2014 
procedures, state and local agencies also need to consider how the 
model affects regional conformity analysis results and whether SIP and/
or transportation plan/TIP changes are necessary to assure future 
conformity determinations. As stated earlier in the notice, the changes 
to EMFAC impact emission factors for each area in California. CARB has 
requested an 18-month grace period to allow them to update SIPs 
previously developed using EMFAC2007 or EMFAC2011 with the updated 
emissions from EMFAC2014 during 2016. Therefore, additional time is 
necessary for CARB to revise previously approved SIPs with EMFAC2014 
and complete the SIP revision process, so that MPOs can incorporate 
revised SIP budgets into the transportation conformity process.
    For application of EMFAC2014 at the project level, while EMFAC2014 
was originally released by CARB in October of 2014, project sponsors 
developing future project-level analysis may need some time to 
familiarize themselves with this model.
    Therefore, it is appropriate to set a two-year grace period to 
allow all areas in California to incorporate EMFAC2014 in conformity 
hot-spot analyses and apply the changes to the model structure and 
updated planning assumptions incorporated in EMFAC2014 in a timely 
manner. In the interim, new PM and CO hot-spot analyses that are 
started prior to the end of the EMFAC2014 grace period can be based on 
EMFAC2011 and the EPA's existing PM hot-spot guidance \7\ (40 CFR 

    \7\ See Web page http://www3.epa.gov/otaq/stateresources/transconf/projectlevel-hotspot.htm#pm-hotspot for latest guidance 
documents and information.

    When the grace period ends on December 14, 2017, EMFAC2014 will 
become the only approved motor vehicle emissions model for all new 
regional and hot-spot transportation conformity analyses across 
California, as a means of meeting the requirement to use the latest 
emissions information in conformity analyses (40 CFR 93.111). In 
general, this means that all new HC, NOX, PM10, 
PM2.5, and CO regional conformity analyses and CO, 
PM10 and PM2.5 hot-spot analyses started after 
the end of the two-year grace period must be based on EMFAC2014, even 
if the SIP is based on an earlier version of the EMFAC model. The EPA 
is considering what project-level guidance is necessary for EMFAC2014 
and will make information available on the EPA's Web site: www.epa.gov/otaq/stateresources/transconf/projectlevel-hotspot.htm.
    In addition, in most cases, if an area revises previously approved 
EMFAC2011-based SIP budgets using EMFAC2014, the revised EMFAC2014 
budgets would be used for conformity purposes once the EPA approves the 
SIP revision. In general, the EPA will not make adequacy findings for 
these SIPs because submitted SIPs cannot supersede approved budgets 
until they are approved. However, 40 CFR 93.118(e)(1) allows an 
approved budget to be replaced by an adequate budget if the EPA's 
approval of the initial budgets specifies that the budgets being 
approved may be replaced in the future by new adequate budgets. This 
flexibility has been used in limited situations in the past, such as 
during the transition from EMFAC7F and EMFAC7G to EMFAC2002. See 67 FR 
46618 (July 16, 2002); 67 FR 69139 (November 15, 2002); and 68 FR 15720 
(April 1, 2003). In such cases, the EMFAC2014-based budgets would be 
used for conformity purposes once they have been found adequate. States 
should consult with the EPA as needed

[[Page 77340]]

to determine if this flexibility applies to their situation.

F. Can areas use EMFAC2011 during the grace period?

    Yes, the conformity rule provides some flexibility for regional 
emissions analyses that are started before the end of the grace period. 
Analyses that begin before or during the grace period may continue to 
rely on EMFAC2011. The interagency consultation process should be used 
if it is unclear if an EMFAC2011-based analysis was begun before the 
end of the grace period. When the grace period ends, EMFAC2014 will 
become the EPA-approved motor vehicle emissions model for regional 
emissions analyses for transportation conformity in California.
    CO, PM10 and PM2.5 hot-spot analyses for 
project-level conformity determinations can be based on EMFAC2011 if 
the analysis was begun before the end of the grace period, 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)). Therefore quantitative analysis already underway 
that were started before the end of the grace period using EMFAC2011 
can be completed as long as 40 CFR 93.111(c) is satisfied. The 
interagency consultation process should be used if it is unclear 
whether an EMFAC2011-based analysis is covered by the circumstances 
described in the conformity rule.

G. Future Updates to EMFAC

    On January 31, 2006, CARB submitted a letter to the EPA and to the 
California Division of the FHWA indicating the State's intention to 
make future revisions to update EMFAC. These EMFAC updates would 
reflect, among other new information, updated vehicle fleet data every 
three years. In California, MPOs and Air Districts have not been able 
to update vehicle fleet data embedded into EMFAC. The EPA's July 2004 
final rule (69 FR 40004) states that new vehicle registration data must 
be used when it is available prior to the start of new conformity 
analyses and that states and MPOs are strongly encouraged to update the 
data at least every five years as described in EPA/USDOT December 2008 
guidance.\8\ The next update to the planning assumptions in EMFAC is 
expected in 2017.

    \8\ For more information on qualitative PM hot-spot analyses, 
see the EPA and the FHWA's joint ``Guidance for The Use of Latest 
Planning Assumptions in Transportation Conformity Determinations'' 
(EPA420-B-08-901, December 2008).

III. Summary of EPA Actions

    As described in this notice, the EPA is approving and announcing 
the availability of EMFAC2014 as submitted by CARB on May 21, 2015 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 HC, CO, NOx, PM10, PM2.5, 
lead, and sulfur oxides. In addition, EMFAC2014 will be used in 
transportation conformity regional emissions analyses for pollutants 
and precursors that are applicable in a given nonattainment or 
maintenance area. The EPA is approving the emission factor elements of 
EMFAC2014, but not the associated default travel activity (e.g. Vehicle 
Miles Traveled). The EPA is also approving EMFAC2014's Emission Rate 
Mode that allows the model to estimate project-level emissions for CO, 
PM10 and PM2.5 conformity hot-spot analyses.
    (3) A 24-month statewide transportation conformity grace period 
will be established beginning December 14, 2015 and ending December 14, 
2017 for the transportation conformity uses described in (2) above.

    Dated: December 2, 2015.
Jared Blumenfeld,
Regional Administrator, Region IX.
[FR Doc. 2015-31307 Filed 12-11-15; 8:45 am]