[Federal Register Volume 84, Number 158 (Thursday, August 15, 2019)]
[Notices]
[Pages 41717-41720]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2019-17476]


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ENVIRONMENTAL PROTECTION AGENCY

[EPA-R09-OAR-2019-0472; FRL-9998-27-Region 9]


Official Release of EMFAC2017 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: 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. 
EMFAC2017 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 
EMFAC2017, rather than EMFAC2014, 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 EMFAC2017 emissions model for SIP and 
conformity purposes is effective August 15, 2019. EMFAC2017 must be 
used as described in this Notice for all new regional emissions 
analyses for transportation conformity purposes that are started on or 
after August 16, 2021 and for all new carbon monoxide (CO) and 
particulate matter (PM10 and PM2.5) hot-spot 
analyses that are started on or after August 17, 2020.

FOR FURTHER INFORMATION CONTACT: Karina O'Connor, 
[email protected], (775) 434-8176, Air Planning Office (AIR-2), 
Air and Radiation Division, U.S. EPA, Region 9, 75 Hawthorne Street, 
San Francisco, California 94105-3901.

SUPPLEMENTARY INFORMATION: Copies of the official version of the 
EMFAC2017 model, including technical support documents, are available 
on the California Air Resources Board (CARB) website: http://www.arb.ca.gov/msei/categories.htm#onroad_motor_vehicles.
    Throughout this document, ``we,'' ``us,'' and ``our'' refer to the 
EPA.

I. Background

A. What is the EMFAC model?

    The EMFAC model is a computer model that can estimate emissions 
rates for on-road mobile sources (``motor vehicles'') for calendar 
years 2000 to 2050 operating in California. Pollutant emissions for 
hydrocarbons (HC), CO, nitrogen oxides (NOX), 
PM10, PM2.5, carbon dioxide (CO2), and 
sulfur oxides are output from the model. Emissions are calculated for 
over forty 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 per 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 SIP and 
transportation conformity requirements under the CAA. 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.

[[Page 41718]]

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

    Most SIPs in California were developed using EMFAC2014 (released by 
CARB in December 2014) or EMFAC2011 (released by CARB in September 
2011). The EPA approved and announced the availability of EMFAC2014 on 
December 14, 2015 (80 FR 77337) and approved and announced the 
availability of EMFAC2011 on March 16, 2013 (78 FR 14533) for all 
nonattainment and maintenance areas in California.
    EMFAC2014 was considered a major update to previous versions of 
EMFAC and most SIPs in California were updated with EMFAC2014 in the 
2015-2018 timeframe. EMFAC2014 included a new model structure, new data 
and methodologies regarding calculation of motor vehicle emissions, and 
revisions to implementation data for control measures.

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 July 20, 2018 letter, CARB requested that the EPA 
approve EMFAC2017 for use in developing SIPs and in determining 
conformity in California.\1\ As described further below, EMFAC2017 is a 
significant change from previous EMFAC models and can calculate motor 
vehicle emissions for all areas in California. EMFAC2017 is being 
approved as the latest emissions model for statewide use in SIP 
development and emissions analyses for conformity purposes. Because 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.
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    \1\ The EMFAC2017 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 https://ww3.arb.ca.gov/msei/downloads/emfac2017-volume-iii-technical-documentation.pdf.
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II. EPA Action

A. What version of EMFAC is the EPA approving?

    In this notice, the EPA is approving and announcing that EMFAC2017 
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. 
EMFAC2017 was developed by CARB and transmitted for approval to the EPA 
on July 20, 2018.\2\
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    \2\ EMFAC2017, v1.0.2 (March 1, 2018 release).
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    The EMFAC2017 model uses the same structure, using Python and MySQL 
software, as EMFAC2014. This structure was developed to allow CARB to 
incorporate updated regulations and emissions data into the model and 
provide for a simplified user experience. The model is operated in 
either the Emissions Mode or the Emissions Rate Mode for regional 
emissions analyses to access emissions databases and vehicle activity 
data for the appropriate geographic subarea. EMFAC2017 also includes 
the Project-Level Assessment (EMFAC2017-PL) feature, which is available 
when EMFAC2017 is run in Emissions Rate Mode. The design of this part 
of EMFAC has not significantly changed from EMFAC2014. When using 
EMFAC2017-PL, emissions rates are estimated based on user-specified, 
project-specific conditions. An updated handbook for using EMFAC2017 at 
the project level is available from CARB at: https://www.arb.ca.gov/msei/downloads/emfac2017-volume-ii-pl-handbook.pdf. EMFAC2017 allows 
users to run one model for SIP inventories, regional emissions 
analyses, and project analyses.

B. What analyses can EMFAC2017 be used for?

    The EPA is approving the model to estimate regional emissions of 
HC, CO, NOX, PM10, PM2.5, and sulfur 
oxides.\3\ However, EMFAC2017 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.
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    \3\ The EPA notes that EMFAC2017 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.
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    The EPA is also approving EMFAC2017 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 
intersection. Hot-spot analyses are completed for only certain types of 
transportation projects; see 40 CFR 93.123(a) and (b) for further 
information.
    The EPA also notes that today's approval action does not affect the 
methodology required for calculating re-entrained road dust for 
PM10 and PM2.5 SIPs and transportation conformity 
analyses. Estimates for PM10 and PM2.5 in 
EMFAC2017 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.\4\ In addition, EMFAC2017 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.
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    \4\ 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.''
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C. Why does the EPA consider EMFAC2017 to be a major update to EMFAC?

    EMFAC2017 includes new data and significant changes to the 
methodologies regarding calculation of motor vehicle emissions and 
revisions to implementation data for control measures. EMFAC2017 
includes updated emissions factors and data on car and truck 
activities, and emissions reductions associated with new regulations 
supporting new estimates of emissions from heavy-heavy duty diesel 
trucks and buses.\5\ New emissions factor data was developed based on 
data from EPA's In-Use Vehicle Program, CARB's Vehicle and Truck and 
Bus Surveillance Programs, CARB's PEMs and Transit Bus testing and 
Integrated Bus Information Systems of West Virginia and Altoona. Motor 
vehicle fleet age, vehicle types and vehicle population

[[Page 41719]]

have also been updated based on 2013-2016 California Department of 
Motor Vehicle (DMV) data, International Registration Plan (IRP) data, 
Truck Regulation Upload, Compliance, and Reporting System (TRUCRS) 
data, Port Vehicle Identification Number (VIN) data, California Highway 
Patrol School Bus Inspections and National Transit Database 
information. Each of these changes affect emissions factors for each 
area in California. The EMFAC2017 model interface and overall design 
has not significantly changed as compared to EMFAC2014. CARB's website 
describes these and other model changes at: https://ww3.arb.ca.gov/msei/msei.htm.
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    \5\ Regulations include the Federal Phase 2 Greenhouse Gas 
Standards, California Senate Bill 1 which impacts compliance 
assumptions in EMFAC2017 for CARB's Truck and Bus Regulation and 
Updates to CARB's Advanced Clean Cars regulations from CARB's 2017 
Midterm review.
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D. How were stakeholders and the public involved in the EMFAC 
development process?

    Since 2017, 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.\6\ 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. CARB also developed and posted 
training modules for EMFAC2017 and supports a mobile source emissions 
inventory email listserv to announce updates and changes to the EMFAC 
supporting material.\7\
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    \6\ See http://www.arb.ca.gov/msei/workshop-meetings.htm.
    \7\ To subscribe to CARB's listserv for Mobile Source Emission 
Inventory development, see ``Join our MSEI listserv'' at https://www.arb.ca.gov/msei/categories.htm#onroad_motor_vehicles.
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    CARB also made available to the public a technical document that 
describes updates to the model and public presentations that summarize 
the changes from earlier versions of the model. The technical 
documentation and presentations are available on CARB's website at: 
https://www.arb.ca.gov/msei/categories.htm.
    Specific changes incorporated into the EMFAC2017 model are also 
discussed in https://www.arb.ca.gov/msei/downloads/emfac2017-volume-iii-technical-documentation.pdf. All presentations from the public 
workshops are available on the CARB website 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?

    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 EMFAC2017, 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 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 EMFAC2017 is required for all new HC, 
NOX, PM10, PM2.5 and CO regional 
emissions analyses (e.g., supporting transportation plan and TIP 
conformity determinations).
    The grace period for regional emissions analyses begins on August 
15, 2019 and ends on August 16, 2021. Areas have the option of using 
the new model for regional emissions analyses prior to the end of the 
grace period.
    Upon consideration of the transportation conformity rule's factors, 
the EPA is also establishing a one-year grace period before EMFAC2017 
is required in conformity analyses for all new CO, PM10 and 
PM2.5 hot-spot analyses supporting project-level conformity 
determinations.
    The grace period for hot-spot analyses begins on August 15, 2019 
and ends on August 17, 2020. Areas have the option of using the new 
model for hot-spot analyses prior to the end of the grace period.
    As discussed earlier in the notice, EMFAC2017 incorporates 
significant changes to the emissions and vehicle fleet data assumptions 
used to estimate emissions for regional emissions analysis. In addition 
to incorporating the new EMFAC2017 emissions rate and fleet data, 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 affect emissions 
factors for each area in California. CARB has requested a 24-month 
grace period to allow them to update SIPs previously developed using 
EMFAC2011 or EMFAC2014 with the updated emissions from EMFAC2017. CARB 
anticipates that 24 months are needed to develop and submit revised 
SIPs based on EMFAC2017. The EPA agrees that additional time is 
necessary for CARB to revise previously approved SIPs with EMFAC2017 
and complete the SIP revision process so that MPOs can incorporate 
revised SIP motor vehicle emission budgets (``budgets'') into the 
transportation conformity process.
    For application of EMFAC2017 at the project level, the application 
of EMFAC2017 and the model's overall design and interface are similar 
to EMFAC2014. As a result, project sponsors developing future hot-spot 
analyses for projects that require such analyses in CO and PM 
nonattainment and maintenance areas that have already used EMFAC2014 
should not need significant time to familiarize themselves with this 
model.\8\ In addition, the fact that time may be needed for revising 
SIPs or transportation plans/TIPs due to the emissions factor changes 
in EMFAC2017 is irrelevant for hot-spot analyses, because hot-spot 
analyses do not rely upon such planning documents. But while 
EMFAC2017's model design and interface has not significantly changed 
from EMFAC2014, project

[[Page 41720]]

sponsors may still need some time to familiarize themselves with CARB's 
updated EMFAC2017-PL handbook and consider technical resource 
allocation issues to incorporate EMFAC2017 into any future hot-spot 
analyses in multiple CO, PM10, and PM2.5 
nonattainment and maintenance areas across California.
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    \8\ EPA is not providing new or updated hot-spot training or 
guidance for hot-spot analyses due to EMFAC2017.
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    Therefore, it is appropriate to set a one-year grace period to 
allow all areas in California to incorporate EMFAC2017 in conformity 
hot-spot analyses for required project types and apply the updated 
planning assumptions incorporated in EMFAC2017 in a timely manner. In 
the interim, new PM and CO hot-spot analyses that are started prior to 
the end of the EMFAC2017 grace period can be based on (40 CFR 
93.111(c)).\9\
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    \9\ See web page http://www3.epa.gov/otaq/stateresources/transconf/projectlevel-hotspot.htm#pm-hotspot for latest guidance 
documents and information.
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    When the regional emissions analysis grace period ends on August 
16, 2021, EMFAC2017 will become the only approved motor vehicle 
emissions model for all new regional transportation conformity analyses 
in California for meeting the requirement to use the latest emissions 
information in conformity analyses. In general, this means that all new 
HC, NOX, PM10, PM2.5, and CO regional 
conformity analyses started after the end of the two-year grace period 
must be based on EMFAC2017, even if the SIP is based on an earlier 
version of the EMFAC model.
    In addition, in most cases, if an area revises previously approved 
EMFAC2014-based SIP budgets using EMFAC2017, the revised EMFAC2017 
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.\10\ In 
such cases, the EMFAC2017-based budgets would be used for conformity 
purposes once they have been found adequate. California air agencies 
should consult with the EPA as needed to determine if this flexibility 
applies.
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    \10\ See 67 FR 46618 (July 16, 2002); 67 FR 69139 (November 15, 
2002); and 68 FR 15720 (April 1, 2003).
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    When the hot-spot analysis grace period ends on August 17, 2020, 
EMFAC2017 will become the only approved motor vehicle emissions model 
for all new hot-spot transportation conformity analyses for required 
project types across California for meeting the requirement to use the 
latest emissions information in conformity. In general, this means that 
all new CO, PM10, and PM2.5 hot-spot analyses 
started after the end of the one-year grace period must be based on 
EMFAC2017 rather than EMFAC2014.

F. Can areas use EMFAC2014 during the grace period?

    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 EMFAC2014. The inter-agency consultation process should be used 
if it is unclear if an EMFAC2014-based analysis was begun before the 
end of the 24-month grace period. When the grace period ends, EMFAC2017 
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 EMFAC2014 if 
the analysis was begun before the end of the 12-month 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.\11\ Quantitative analysis already underway that was started 
before the end of the grace period using EMFAC2014 can be completed as 
long as 40 CFR 93.111(c) is satisfied. The inter-agency consultation 
process should be used if it is unclear whether an EMFAC2014-based 
analysis is covered by the circumstances described in the 
transportation conformity rule.
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    \11\ 40 CFR 93.111(c).
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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 cannot update 
vehicle fleet data embedded into EMFAC, only CARB can update the fleet 
data with each new EMFAC update because of the model design. 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 guidance 
issued December 2008 by the EPA and DOT.\12\ CARB's next update to the 
planning assumptions in EMFAC is expected in 2020.
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    \12\ For more information on qualitative PM hot-spot analyses, 
see the EPA and DOT's joint ``Guidance for The Use of Latest 
Planning Assumptions in Transportation Conformity Determinations'' 
(EPA420-B-08-901, December 2008).
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III. Summary of EPA Actions

    As described in this notice, the EPA is approving and announcing 
the availability of EMFAC2017 as submitted by CARB on July 20, 2018 
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, 
and sulfur oxides. In addition, EMFAC2017 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 emissions factor elements of 
EMFAC2017, but not the associated default travel activity (e.g. Vehicle 
Miles Traveled).
    (3) A 24-month statewide transportation conformity regional grace 
period will be established beginning August 15, 2019 and ending August 
16, 2021 for the transportation conformity uses described in (2) above.
    (4) The EPA is also approving EMFAC2017's Emission Rate Mode that 
allows the model to estimate project-level emissions for CO, 
PM10, and PM2.5 conformity hot-spot analyses.
    (5) A 12-month statewide transportation conformity hot-spot grace 
period will be established beginning August 15, 2019 and ending August 
17, 2020 for the transportation conformity uses described in (4) above.

    Dated: August 6, 2019.
Michael Stoker,
Regional Administrator, EPA Region IX.
[FR Doc. 2019-17476 Filed 8-14-19; 8:45 am]
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