MOVES5 Policy Guidance
Use of MOVES for State Implementation
Plan Development, Transportation
Conformity, General Conformity,
and Other Purposes
SEPA
United States
Environmental Protection
Agency
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MOVES5 Policy Guidance
Use of MOVES for State Implementation
Plan Development, Transportation
Conformity, General Conformity,
and Other Purposes
Office of Transportation and Air Quality
U.S. Environmental Protection Agency
United States
Environmental Protection
^1 Agency
EPA-420-B-24-038
November 2024
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Table of Contents
Section 1. Introduction 3
1.1 What is the purpose of this guidance? 3
1.2 How does EPA distinguish model versions? 5
1.3 What is MOVES5, and how does it compare to MOVES4? 5
1.4 What resources are available to assist in implementing MOVES5? 7
1.5 Does this guidance create new requirements? 9
Section 2. Using MOVES5 in SIPs 10
2.1 How does the release of MOVES5 affect SIPs that are currently under
development? 10
2.2 How does the release of MOVES5 affect SIPs that have already been submitted or
approved? 11
2.3 When existing SIPs and budgets are revised with MOVES5, what do states need to
submit to show that a SIP continues to meet applicable requirements? 11
2.4 If motor vehicle emissions budgets in a SIP need to be redone with MOVES5 or if
a state needs to address additional RFP years, should the base year also be
remodeled with MOVES5? 14
2.5 How will MOVES5 affect the need for emissions reductions in the development of
future attainment or maintenance SIPs? 15
2.6 Can MOVES5 be used for vehicle emission inspection and maintenance
performance standard modeling for 2015 ozone NAAQS SIPs? 15
Section 3. Using MOVES5 in Transportation Conformity 17
3.1 What is transportation conformity? 17
3.2 When will the use of MOVES5 be required for regional emissions analyses in
transportation plan and TIP conformity determinations? 17
3.3 Does the release of MOVES5 with a new conformity grace period affect the
previous conformity grace period established when MOVES4 was released? 18
3.4 Under what circumstances will the MOVES5 grace period for regional emissions
analyses be shorter than two years? 18
3.5 How will the MOVES5 conformity grace period be implemented for regional
emissions analyses? 19
3.6 When will the use of MOVES5 be required for hot-spot analyses in project-level
conformity determinations? 20
3.7 How will the MOVES5 grace period be implemented for CO, PMio and PM2.5 hot-
spot analyses? 21
3.8 How will MOVES5 affect FHWA's CO categorical hot-spot finding? 22
3.9 How will MOVES5 affect CO hot-spot protocols that were previously approved
into the SIP? 22
3.10When does the MOVES4 conformity grace period end? 22
Section 4. Using MOVES5 in General Conformity 24
4.1 When will the use of MOVES5 be required under the General Conformity Rule?
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Section 5. Using MOVES5 for Other Purposes 25
5.1 Can MOVES5 be used to estimate greenhouse gas emissions? 25
5.2 Can MOVES5 be used to estimate mobile source air toxics (MSATs)? 25
5.3 What role will MOVES5 play in EPA's National Emissions Inventory? 26
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Section 1. Introduction
1.1 What is the purpose of this guidance?
This guidance describes how and when to use the latest version of the MOtor Vehicle
Emission Simulator (MOVES) emissions model for state implementation plan (SIP)
development, transportation conformity determinations, general conformity
determinations, and other purposes. This guidance applies to the current version of
MOVES5, as well as any future MOVES5 minor revisions.1 This guidance supersedes
the previous August 2023 version of the MOVES4 guidance (EPA-420-B-23-009).
MOVES5 is the U.S. Environmental Protection Agency's (EPA's) latest official motor
vehicle emissions model for state and local agencies to estimate nitrogen oxides (NOx),
particulate matter (PM2.5 and PM10), volatile organic compounds (VOCs), carbon
monoxide (CO), and other pollutants/precursors from cars, trucks, buses, and motorcycles
for SIP purposes and transportation conformity determinations outside of California.2
MOVES5 incorporates EPA's regulations that have been finalized as of the model's
release, including th q Multi-Pollutant Emissions Standards for Model Years 2027 and
Later Light-Duty and Medium-Duty Vehicles final rule and the Greenhouse Gas
Emissions Standards for Heavy-Duty Vehicles—Phase 3 final rule. The model also
incorporates new data for modeling light-duty (LD) and heavy-duty (HD) brake wear
emissions, as well as other changes. See Section 1.3 for more information about the new
information in MOVES5.
This guidance is organized as follows:
• Section 1: introduction, including information about MOVES5 and resources
available;
Section 2
Section 3
Section 4
Section 5
using MOVES5 in SIPs;
using MOVES5 in transportation conformity;
using MOVES5 in general conformity; and
using MOVES5 for other purposes such as greenhouse gas planning.
EPA will be publishing a Federal Register notice to announce the availability of
MOVES5 for official purposes. All states other than California should use MOVES5 for
both onroad and nonroad sectors for future SIPs to take full advantage of the
improvements incorporated in this version. However, state and local agencies that have
already completed significant work on a SIP with a previous MOVES version may
continue to use it for that SIP. See Section 2 for further information on using MOVES in
SIP development. Section 2 also includes information on using MOVES5 for vehicle
1 Details on MOVES can be found at www.epa.gov/moves.
2 In California, a different onroad emissions model, EMFAC, is used for regulatory purposes instead of
MOVES. MOVES can also model emissions in the District of Columbia, Puerto Rico, and the U.S. Virgin
Islands.
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inspection and maintenance (I/M) performance standard modeling for state I/M SIPs for
the 2015 ozone national ambient air quality standard (NAAQS) (see Section 2.6).
EPA intends to include in the Federal Register notice a two-year grace period for using
MOVES5 for regional transportation conformity purposes and a two-year grace period
for project-level conformity purposes.3 EPA coordinated with the U.S. Department of
Transportation (DOT) on the length of the conformity grace period. MOVES5 will need
to be used for new regional emissions analyses for transportation conformity
determinations begun after the two-year conformity grace period ends. MOVES5 will
also need to be used for new PM and CO hot-spot analyses for project-level conformity
determinations begun after the two-year project-level grace period ends. See Section 3
for further information on using MOVES5 in transportation conformity determinations.
In addition, see Section 4 for information on using MOVES4 in general conformity
determinations.
Note that the intended two-year conformity grace period for using MOVES5 is separate
and distinct from the two-year conformity grace period for using the previous version of
the model, MOVES4. The two-year grace period established by EPA's September 2023
MOVES4 Notice of Availability in the Federal Register is unchanged by the release of
MOVES5 and continues to be in effect until September 12, 2025. See Section 3 for more
details.
EPA has also included information regarding the use of MOVES for estimating mobile
source air toxic (MSAT) and greenhouse gas (GHG) emissions in this guidance.
Although there are no SIP or conformity requirements for these pollutants, MOVES5 is
EPA's best tool for estimating air toxics and GHG emissions from onroad and nonroad
mobile sources for regulatory as well as nonregulatory purposes. MOVES5 also may be
used for calculating both onroad and nonroad GHG and co-pollutant emission reductions
for Bipartisan Infrastructure Law and Inflation Reduction Act programs. See Section 5
for further information about using MOVES to estimate GHGs and air toxics. This
section also explains how MOVES5 will be used in the 2023 National Emissions
Inventory (NEI).
Questions about the application of this guidance to specific SIPs or transportation
conformity determinations should be addressed to the EPA Regional Office SIP or
transportation conformity contact. Regional contacts for transportation conformity can
be found at the EPA Regional Contacts for State and Local Transportation website. A list
of the EPA Regional mobile source contacts can be found at the Office of Transportation
and Air Quality Contact by Topic website in Section 16.2, last page. Other questions
regarding specific topics should be addressed to the corresponding EPA staff listed at that
same website.
In addition, the following EPA contacts are available for general questions regarding this
guidance:
3 See 40 CFR 93.111(b).
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• for general questions about the MOVES model, email mobile@epa.gov;
• for SIP questions, contact Kaitlyn Leffert (leffert.kaitlyn@epa.gov);
• for transportation conformity questions, contact Aaron Letterly
(letterly. aaron@epa. gov);
• for general conformity questions, contact Virginia Raps
(raps.virginia@epa.gov); and
• for questions about the National Emissions Inventory, contact Janice Godfrey
(godfrev.ianice@epa.gov).
The M0VES5 Federal Register Notice of Availability will be available at EPA's
transportation conformity website for Policy and Technical Guidance. The M0VES4
Federal Register Notice of Availability is also found at the same website.
1.2 How does EPA distinguish model versions?
M0VES5 is a major revision to the MOVES series of models. This model is the fifth
major MOVES release.4 As shown in Table 1, future minor revisions would be
designated by increments of the number after a decimal point (e.g., M0VES5.1). EPA
may also use an additional decimal point to designate minor patches (e.g., MOVES5.0.1).
Table 1: MOVES Naming Convention
Type of Release
Naming Convention
Examples
Major release
"MOVES" followed by the next
number in sequence
MOVES 5
Minor revision
Addition of a decimal followed by the
next number in sequence
M0VES5.1,
MOVES5.2
Minor patch, e.g.,
new user features
Addition of a second decimal followed
by the next number in sequence
MOVES5.0.1,
MOVES5.0.2
References to "M0VES5" in this guidance refer to "M0VES5" and any future minor
revisions to M0VES5. References to "M0VES4" in this guidance relate to all versions
of M0VES4, and references to "M0VES3" relate to all versions of M0VES3.
1.3 What is MO VES5, and how does it compare to MO VES4?
MOVES is EPA's state-of-the-science model for estimating emissions from onroad
mobile sources. M0VES5 also models most nonroad emissions sources.5
4 For more information, see EPA's Previous MOVES Versions and Documentation website.
5 The nonroad emission sources not included in MOVES are aircraft, commercial marine engines, and
locomotives.
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M0VES5 is a major revision to the MOVES series of models and is the latest emissions
model for SIP and conformity purposes. MOVES5 includes new vehicle emissions
standards as well as new emissions and activity data. As a result of these changes,
estimates of emissions from MOVES5 may be different from earlier versions of MOVES.
The structure of MOVES5 is fundamentally the same as MOVES4, but, as described
below, certain emissions rates and activity updated in MOVES5 differ from MOVES4.
The net impact of these changes on calculated emissions will depend on many factors,
including the specific area being modeled and the inputs used.
MOVES5 incorporates several important updates, including:
• Accounting for EPA's Light- and Medium-Duty Multi-Pollutant Rule with higher
projected electric vehicle (EV) fractions and more stringent standards for carbon
dioxide (CO2), particulate matter (PM), non-methane organic gases (NMOG), and
oxides of nitrogen (NOx).6
• Accounting for EPA's Heavy-Duty Greenhouse Gas Emissions-Phase 3 Rule with
higher projected EV fractions and updated energy consumption estimates for
heavy-duty EVs.7
• Incorporating new data on light-duty (LD) and heavy-duty (HD) brake wear
emissions.
• Expanding detailed calculations to vehicles up to 40 years old, instead of 30.
• Updating onroad and nonroad fuel properties for calendar year 2021 and later.
• Updating historical and forecast default vehicle miles travelled (VMT), vehicle
populations, age distributions, and fuel distributions.
For additional information on the updates included in MOVES5, please refer to the
Overview of EPA's MOtor Vehicle Emissions Simulator (MOVES5), found at EPA's
MOVES website. Specific information about MOVES5 inputs and algorithms can be
found on EPA's websites for MOVES Onroad Technical Reports and MOVES Nonroad
Technical Reports.
MOVES is a flexible model using an array of input and output options, allowing more
than one way to use MOVES to develop emissions estimates. Like its predecessors,
MOVES5 includes the capability to estimate vehicle exhaust and evaporative emissions
as well as brake wear and tire wear emissions for criteria pollutants and precursors. Also
like previous versions, MOVES5 does not include the capability to estimate emissions of
6 See EPA's final rule, "Multi-Pollutant Emissions Standards for Model Years 2027 and Later Light-Duty
and Medium-Duty Vehicles," published in the Federal Register on April 18, 2024 (89 FR 27842).
7 See EPA's final rule, "Greenhouse Gas Emissions Standards for Heavy-Duty Vehicles—Phase 3,"
published in the Federal Register on April 22, 2024 (89 FR 29440).
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re-entrained road dust. To estimate emissions from re-entrained road dust, practitioners
should continue to use the latest approved methodologies.8
EPA performed a comparison of onroad emissions from MOVES5 to emissions from
MOVES4 using default information in MOVES5 at the national level, and for three
sample urban counties with different local travel patterns and ambient conditions. In
general, compared to MOVES4, MOVES5 emissions of NOx, PM2.5, VOC, CO, and
sulfur dioxide (SO2) tend to be higher in the 2020s and 2030s. In the longer term,
emissions of these pollutants in MOVES5 are lower due to the emissions reductions of
new EPA regulations. Emissions of CO2 are lower in both the short and long term
because of new regulations. Nonroad emissions of SO2 have increased due to increased
sulfur content in post-2021 gasoline.
Note that results will vary based on the pollutant selected and an area's local inputs.
Based on our testing, modelers who do very large runs may expect slower run time with
MOVES5 compared to MOVES4. See EPA's MOVES5 Technical Guidance, referenced
in Section 1.4, for recommendations for improving run time within the MOVES5.9
1.4 What resources are available to assist in implementing MO VES5 ?
In addition to this guidance document, EPA has developed technical guidance to assist in
implementing MOVES5:
• MOVES5 Technical Guidance: Using MOVES to Prepare Emission Inventories in
State Implementation Plans and Transportation Conformity (available on EPA's
transportation conformity Policy and Technical Guidance for State and Local
Transportation website) provides guidance on how to set up a MOVES run and
add local data using the County Data Manager for SIPs and regional
transportation conformity analyses.
Other existing MOVES guidance generally apply to using MOVES5, including:
• PMHot-Spot Guidance: Transportation Conformity Guidance for Quantitative
Hot-spot Analyses in PM2.5 and PM10 Nonattainment and Maintenance Areas
explains how to use MOVES to complete hot-spot analyses required for projects
of local air quality concern in PM2.5 and PM10 nonattainment and maintenance
8 See EPA's Notice of Availability, "Official Release of the January 2011 AP-42 Method for Estimating
Re-Entrained Road Dust from Paved Roads," published in the Federal Register on February 4, 2011 (76
FR 63281.
9 EPA has provided tips for faster MOVES runs with MOVES installation. For those with MOVES
installed, see file found at: "\docs\TipsForFasterMOVESRuns.md". These same tips can be found at the
EPA GitHub site,
https://github.com/USEPA/EPA MOVES Model/blob/master/docs/TipsForFasterMOVESRuns.md.
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areas. The latest version is available on EPA's Project-Level Conformity and
Hot-Spot Analyses website.
• UsingMOVES3 in Project-Level Carbon Monoxide Analyses describes how to
use the MOVES emissions model to estimate CO emissions from transportation
projects. The latest version is available on EPA's Project-Level Conformity and
Hot-Spot Analyses website.
• Hot-spot Analyses and Project-Level Conformity Determinations FAQs, also on
EPA's Project-Level Conformity and Hot-Spot Analyses website, includes an
FAQ about the use of MOVES in PM and CO hot-spot analyses.
• Performance Standard Modeling for New and Existing Vehicle Inspection and
Maintenance (I/M) Programs Using MOVES Mobile Source Emissions Model
describes when and how to conduct performance standard modeling to
demonstrate in an I/M SIP that a vehicle emission I/M program meets the
applicable performance standard as defined within the I/M regulations. The latest
version is available on EPA's Vehicle Emissions I/M: Policy and Technical
Guidance website.
• Port Emissions Inventory Guidance: Methodologies for Estimating Port-Related
and Goods Movement Mobile Source Emissions describes state-of-the-science
methodologies for preparing an emissions inventory for the mobile source sectors
found at ports and freight terminals, including ocean-going vessels, harbor craft,
recreational marine, cargo handling equipment, onroad vehicles, and rail. The
latest version of this guidance is available at EPA's Port Emissions Inventory
Guidance website.
• MOVES GHG Guidance: Using MOVES for Estimating State and Local
Inventories of Onroad and Nonroad Greenhouse Gas Emissions and Energy
Consumption describes how to use MOVES to estimate greenhouse gas emissions
and/or energy consumption from onroad vehicles in a state or metropolitan
area. EPA recently updated this guidance to reflect changes we made to MOVES
specifically to facilitate modeling GHG emissions. The latest version is available
on EPA's Estimating Greenhouse Gas Emissions website, which has resources for
estimating these emissions from the on-road transportation sector.
Additional training materials, examples, and MOVES technical information are available
at the EPA's websites for MOVES Training and transportation conformity Training and
Presentations. EPA's MOVES Hands-on Training Course contains detailed information
on how to use MOVES, consistent with guidance. The training materials, which include
slides and course files for the hands-on exercises, are designed so that the course can be
self-guided.
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MOVES users are urged to check the MOVES website regularly and subscribe to EPA's
mobile source emissions model listserv to receive EPA email announcements related to
MOVES.
1.5 Does this guidance create new requirements?
No. The discussion in this document is intended solely as guidance. The statutory
provisions and EPA regulations discussed in this document contain legally binding
requirements. This document is not a regulation itself, nor does it change or substitute
for statutory provisions and regulations. Thus, it does not impose legally binding
requirements on EPA, the DOT, states, or the regulated community. EPA retains the
discretion to consider and adopt approaches on a case-by-case basis that may differ from
this guidance, but still comply with the statute and regulations. Any decisions regarding
a particular SIP or conformity determination will be made based on the statute and
regulations. This guidance may be revised periodically without an opportunity for public
comment.
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Section 2. Using MOVES5 in SIPs
2.1 How does the release of MOVES 5 affect SIPs that are currently
under development?
The Clean Air Act (CAA) and implementation rules for the NAAQS require that SIP
inventories and control measures be based on the most current information and applicable
models that are available when a SIP is developed.10 MOVES5 should be used in ozone,
CO, PM, and NO2 SIP development as expeditiously as possible, as there is no grace
period for the use of MOVES5 in SIPs.
States should use the latest version of MOVES that is available at the time that a SIP is
developed. All states other than California should use MOVES5 for SIPs that will be
submitted in the future so that they are based on the most accurate estimates of emissions
possible. States that have adopted California regulations under CAA section 177 should
use MOVES5 when modeling any such regulations that have been issued a waiver by
EPA.11
However, EPA recognizes the time and level of effort involved in SIP development, so in
cases where state and local agencies have already completed significant work on a SIP
with MOVES4 (e.g., attainment modeling has already been completed with MOVES4),
they may continue to rely on this earlier version. In addition, due to the fact that EPA is
releasing multiple versions of MOVES in a short timeframe, MOVES3 may have already
been used in SIP development. In areas where state and local agencies have already
completed significant work on a SIP with MOVES3, MOVES3 may continue to be used
in SIP development. EPA believes this would be only a limited number of cases. The
interagency consultation process must be used to develop any SIP revision based on
MOVES (40 CFR 93.105(a)(1) and (b)). States should consult with their EPA Regional
Office if they have questions about how MOVES5 affects SIPs under development in
specific nonattainment or maintenance areas. Early consultation can facilitate EPA's
adequacy finding for transportation conformity purposes or for the SIP approval process.
As discussed in Section 3, new regional emissions analyses that support transportation
plan and transportation improvement program (TIP) conformity determinations and are
started after the end of the conformity grace period must be based on the latest emissions
model available. (40 CFR 93.111). Therefore, incorporating MOVES5 into the SIP now
could assist areas in mitigating possible transportation conformity difficulties in the
future after the MOVES5 conformity grace period ends. See Section 3 for more
information on using MOVES5 for regional emissions analyses and transportation plan
and TIP conformity.
10 See Clean Air Act section 172(c)(3). Also see the discussion of emissions inventory requirements in the
"Fine Particulate Matter National Ambient Air Quality Standards: State Implementation Plan
Requirements" rule (81 FR 58029. August 24, 2016) and in the "Implementation of the 2015 National
Ambient Air Quality Standards for Ozone: Nonattainment Area State Implementation Plan Requirements"
rule (83 FR 63022. December 6, 2018).
11 Procedures for such modeling are detailed in the MOVES5 Technical Guidance.
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2.2 How does the release of MOVES 5 affect SIPs that have already been
submitted or approved?
The CAA does not require states to revise submitted SIPs or SIPs that have already been
approved simply because a new motor vehicle emissions model is now available.12
States can choose to update these SIPs with MOVES5, for example, if it is determined
that it is appropriate to update motor vehicle emissions budgets ("budgets") with the
model for future conformity determinations.13
However, as stated above, states should use MOVES5 where SIP development is in its
initial stages or has not progressed far enough along that switching from a previous
model version would create a significant adverse impact on state resources.
2.3 When existing SIPs and budgets are revised with MOVES5, what do
states need to submit to show that a SIP continues to meet applicable
requirements?
As stated in Section 2.2, a SIP revision would not be required solely due to the release of
MOVES5 for SIPs that have been approved, submitted, or where significant development
has already occurred. However, there may be cases where a state decides to revise an
existing SIP that is based on an older emissions model (e.g., MOVES3 or MOVES2014)
with MOVES5. As discussed below, in addressing these cases, EPA is applying the same
principles it has in the past when motor vehicle emissions budgets (or budgets) have been
revised using a new emissions model. States should consult with their EPA Regional
Office prior to submitting MOVES5 SIP revisions. Early consultation can facilitate
EPA's adequacy finding or SIP approval process.
EPA cannot approve revisions to existing SIPs and budgets unless the revised SIP and
budget meets applicable CAA requirements (e.g., for reasonable further progress (RFP),
attainment, or maintenance). If a state revises an existing SIP with MOVES5, it must
show that the SIP continues to meet applicable requirements with the new level of motor
vehicle emissions calculated by the new model.
In addition, the transportation conformity rule (40 CFR 93.118(e)(4)(iv)) requires that
"the motor vehicle emissions budget(s), when considered together with all other
emissions sources, is consistent with applicable requirements for reasonable further
progress, attainment, or maintenance (whichever is relevant to the given implementation
12 Sierra Club v. EPA. 356 F.3d. 296, 308 (D.C. Cir. 2004) ("To require states to revise completed plans
every time a new model is announced would lead to significant costs and potentially endless delays in the
approval processes ")
13 The conformity rule defines the motor vehicle emissions budget: "Motor vehicle emissions budget is that
portion of the total allowable emissions defined in the submitted or approved control strategy
implementation plan revision or maintenance plan for a certain date for the purpose of meeting reasonable
further progress milestones or demonstrating attainment or maintenance of the NAAQS, for any criteria
pollutant or its precursors, allocated to highway and transit vehicle use and emissions." (40 CFR 93.101).
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plan submission)." This and other regulatory requirements must be satisfied before EPA
can find submitted budgets adequate or approve them for use in the conformity process.
The following describes how to meet applicable requirements for existing SIPs that are
revised with MOVES5, including ideas for how to streamline these revisions whenever
possible.
Use of latest planning assumptions: When SIPs are revised with MOVES5, the motor
vehicle emissions inventories for base year, milestone year and attainment/maintenance
year will need to be recalculated with the latest available planning assumptions. This
should include, at a minimum, the latest information on vehicle miles travelled (VMT),
speeds, fleet mix, and SIP control measures.14 Base year and historical year inventories
should use the latest data available for those years. Future year projection inventories
should also be based on the latest data available.15 If planning assumptions have not
changed since the original SIP was submitted, the state should document this in its new
SIP submission.
In addition, states will need to consider and evaluate whether growth and control strategy
assumptions for non-motor vehicle sources (i.e., stationary, area, and nonroad mobile
sources) are still accurate at the time that the MOVES5 SIP revision is developed to
ensure the revised emissions inventories are consistent with the relevant applicable
requirement (e.g., RFP, attainment, or maintenance). Such assumptions include
population and economic assumptions and any allowable emissions relied upon for
stationary or other sources.
If these assumptions have not changed, the state can explain this and may be able to re-
submit the original SIP with the revised motor vehicle emissions inventories and budgets
to meet the remaining requirements as discussed below. The state may also in these cases
provide summary emissions information for categories of sources and references to the
applicable portions of the original SIP, as long as those portions continue to apply after
the SIP revision with the MOVES5 budgets is approved. Otherwise, the emissions
categories in the SIP that have changed should be brought up to date to ensure that the
emissions inventory is accurate, current, and consistent with the relevant statutory
requirements.16 States should consult with their EPA Regional Office to determine what
should be included in the SIP revision.
14 See EPA and DOT's joint"Guidance for the Use of Latest Planning Assumptions in Transportation
Conformity DeterminationsEPA420-B-08-901, December 2008. This guidance also addresses
requirements for using the latest planning assumptions in SIP development. Also see the discussion of
emissions inventory requirements in the "Fine Particulate Matter National Ambient Air Quality Standards:
State Implementation Plan Requirements" rule (81 FR 58029. August 24, 2016) and in the "Implementation
of the 2015 National Ambient Air Quality Standards for Ozone: Nonattainment Area State Implementation
Plan Requirements'" rule (83 FR 63022. December 6, 2018).
15 See the discussion of emissions inventory requirements in the 'Fine Particulate Matter National Ambient
Air Quality Standards: State Implementation Plan Requirements" rule (81 FR 58029. August 24, 2016) and
in the "Implementation of the 2015 National Ambient Air Quality Standards for Ozone: Nonattainment
Area State Implementation Plan Requirements" rule (83 FR 63022. December 6, 2018).
16 Id.
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Milestone, attainment, or maintenance demonstration: As discussed above, SIP revisions
must continue to show that the SIP still meets applicable CAA requirements (e.g., RFP,
attainment, or maintenance) when previous motor vehicle emissions inventories are
replaced with MOVES5 inventories. The level of analysis and support needed for this
demonstration can vary depending upon how MOVES5 affects the level of motor vehicle
emissions and whether non-motor vehicle inventories require updating. The modeling
and post-processing choices made in the original demonstration could also be a factor.
Areas may be able to revise their motor vehicle emissions inventories and budgets using
MOVES5 without revising the entire SIP or completing additional modeling. This could
be the case if:
(1) the SIP meets applicable requirements when the previous motor vehicle
emissions inventories are replaced with MOVES5 base year and milestone,
attainment, or maintenance year inventories; and
(2) the state can document that the growth and control strategy assumptions for
non-motor vehicle sources continue to be valid and any minor updates do not
change the overall conclusions of the SIP.17
For example, if an ozone SIP relied on changes in emissions from the base year to an
attainment or maintenance year inventory to demonstrate attainment or maintenance, that
requirement would be satisfied by demonstrating that the relative emissions reductions
between the base year and the attainment or maintenance year are the same or greater
using MOVES5 than they were under the model previously used. Similarly, if an ozone
attainment demonstration SIP relied on absolute model predictions to demonstrate
attainment for the future attainment year, that requirement would be satisfied by
demonstrating that the MOVES5 estimates are equal to or lower than the previous
estimates for the future attainment year. Or, if a CO maintenance plan relied on either a
relative or absolute demonstration of maintenance, that requirement could be satisfied by
documenting that the relative emissions reductions between the base year and the
maintenance year are the same or greater using MOVES5.
If both 1 and 2 above are met, the state may be able to submit as the needed SIP revision
the updated motor vehicle emissions budgets along with summary emissions information
for other source categories with references to the applicable portions of the original SIP.
However, if emissions from other source categories in the SIP have changed, those
inventories would have to be brought up to date in order to demonstrate that the SIP
submission complies with the applicable statutory requirement for attainment,
maintenance, or interim milestones. Any changes in control strategies, including
regulations that apply to stationary or area sources and affect those portions of the
17 See the discussion of emissions inventory requirements in the "Fine Particulate Matter National Ambient
Air Quality Standards: State Implementation Plan Requirements" rule (81 FR 58029. August 24, 2016) and
in the "Implementation of the 2015 National Ambient Air Quality Standards for Ozone: Nonattainment
Area State Implementation Plan Requirements" rule (83 FR 63022. December 6, 2018).
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inventories, will need to be factored in to both base and future year inventories to
determine whether the SIP still meets the applicable statutory requirement. However, a
state may not need to revise emissions for a non-motor vehicle emissions inventory
category if a regulatory change resulted in a reduction in emissions in the attainment or
maintenance year relative to the existing SIP. In that circumstance, the SIP could be
assumed to continue to demonstrate attainment or maintenance.
Regardless of the technique used, a more rigorous assessment of a SIP's RFP, attainment,
or maintenance demonstration may be necessary if a state decides to reallocate the
original SIP's excess emissions reductions to the motor vehicle emissions budget(s) as a
safety margin.18 In other words, the state will need to assess how its original
demonstration is affected by using MOVES5 and confirm whether excess emissions
reductions exist prior to allocating them to the budget(s). The assessment of the SIP's
attainment or maintenance demonstration, after onroad emissions are calculated using
MOVES5, would need to be sufficiently detailed to allow the state to determine the
magnitude of the available safety margin, if any, and to decide how much of the available
safety margin to allocate to the motor vehicle emissions budgets for a given year. This
assessment is critical to ensure that SIP budgets in the context of all other emissions
sources continue to meet the conformity rule's adequacy criteria (40 CFR 93.118(e)(4)).
2.4 If motor vehicle emissions budgets in a SIP need to be redone with
MOVES 5 or if a state needs to address additional RFP years, should
the base year also be remodeled with MOVES5?
Yes, a state should redo the base year inventory with MOVES5 in both of those
situations. For example, if the state is revising RFP motor vehicle emissions budgets, and
it has an EPA-approved base year inventory completed with an earlier version of
MOVES, it should recalculate the base year emissions with MOVES5 so that it can verify
that the SIP continues to fulfill RFP requirements. Similarly, if a state is required to
address additional RFP years, it should recalculate the base year emissions so that it can
verify that the SIP will fulfill RFP requirements for the new future years. If the base year
emissions were not recalculated with MOVES5, it would not be possible to tell if RFP
requirements were met because the calculations would be using results from different
versions of the MOVES model.
18 A "safety margin" is the amount by which the total projected emissions from all sources of a given
pollutant are less than the total emissions that would satisfy the applicable requirement for reasonable
further progress, attainment, or maintenance (40 CFR 93.101). A safety margin would be calculated for
each applicable pollutant and precursor for a given NAAQS. See also 40 CFR 93.124(a) for its application.
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2.5 How will MOVES5 affect the need for emissions reductions in the
development of future attainment or maintenance SIPs?
The answer depends upon the unique circumstances of each nonattainment or
maintenance area. The emissions comparisons depend on the pollutants of concern, the
dates of concern, and on existing local regulations, travel activity patterns, fleet age, and
mix of cars and trucks. In some cases, a change from an earlier MOVES version to
MOVES5 may result in increased emissions estimates, while in other cases it may result
in decreased emissions estimates for the relevant time periods.
Moreover, because of the complex chemistry and meteorology of air pollution, the
implications of changes in onroad and nonroad vehicle emissions may not be clear until
multiple years are examined, and the new emissions levels are applied in an air quality
model. Relative differences in emissions over time from an earlier MOVES version to
MOVES5 may be as important as, or more important than, differences between the
models in any one year. Therefore, MOVES5 users should not immediately assume that
increases or decreases in emissions in any single year imply the need for more or fewer
SIP control measures until those changes in emissions have been applied in the complete
SIP context.
An increase in emissions due to the use of MOVES5 may affect an area's ability to
demonstrate conformity for its transportation plan and/or TIP. Areas are encouraged to
consider, through interagency consultation, if and how MOVES5 will impact their future
conformity determinations and discuss any concerns with the appropriate EPA Regional
Office.
2.6 Can MOVES5 be used for vehicle emission inspection and
maintenance performance standard modeling for 2015 ozone NAAQS
SIPs?
For the 2015 ozone NAAQS, states with urbanized ozone nonattainment areas classified
(or reclassified) as Moderate or higher are required to submit an I/M SIP that includes a
performance standard modeling (PSM) analysis per 40 CFR 51.372(a)(2). The purpose
of a PSM analysis is to evaluate whether a vehicle I/M program meets the applicable
performance standard. Procedures relevant to setting up the model, preparing inputs, and
processing results can be found in EPA's PSM guidance.19
As discussed in Section 2.1, because there is no grace period for the use of a new
emissions model in SIP development, MOVES5 should be used to conduct any new PSM
analyses for the 2015 ozone NAAQS. However, as explained above, state and local
agencies that have already completed significant work on a SIP with a previous version
of MOVESprior to the release of MOVES5 may continue to use it for that SIP, and this
includes I/M SIPs. States should consult with their EPA Regional Office if they have
19 Performance Standard Modeling for New and Existing Vehicle Inspection and Maintenance (I/M)
Programs Using the MOVES Mobile Source Emissions Model. October 2022, EPA-420-B-22-034.
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questions about how MOVES5 affects SIPs under development in specific nonattainment
or maintenance areas.
Though California generally uses the EMissions FACtors (EMFAC) model for onroad
mobile emissions modeling, MOVES5 is an appropriate model for PSM applications
within California, assuming all inputs and assumptions are consistent with the vehicle
regulations and I/M program. EPA will address the use of MOVES for I/M PSM in
California in any related action on an I/M SIP.
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Section 3. Using MOVES5 in Transportation Conformity
3.1 What is transportation conformity ?
Transportation conformity is required under CAA section 176(c) (42 U.S.C. 7506(c)) to
ensure that federally funded or approved highway and transit activities are consistent with
("conform to") the purpose of the SIP. Conformity to the purpose of the SIP means that
transportation activities will not cause or contribute to new air quality violations, worsen
existing violations, or delay timely attainment of the relevant NAAQS or any interim
milestones. EPA's transportation conformity rule (40 CFR Parts 51 and 93) establishes
the criteria and procedures for determining whether metropolitan transportation plans,
TIPs, and federally supported highway and transit projects conform to the SIP.
Transportation conformity applies to designated nonattainment and maintenance areas20
for transportation-related criteria pollutants: ozone, PM2.5, PM10, CO, and nitrogen
dioxide (NO2).
3.2 When will the use of MOVES5 be required for regional emissions
analyses in transportation plan and TIP conformity determinations?
EPA will be publishing & Federal Register notice to announce the availability of
MOVES5 for official purposes for states other than California.21 EPA, in consultation
with DOT, intends to establish a two-year grace period before MOVES5 needs to be used
for regional emissions analyses in transportation conformity determinations of
transportation plans and TIPs.22 Section 176(c)(1) of the CAA requires conformity
determinations to be based on "the most recent estimates of emissions." Additionally, the
transportation conformity rule (40 CFR 93.111) requires conformity determinations to be
based on "the latest emission estimation model available," and further states that this
requirement is satisfied if the most current version of EPA's motor vehicle emissions
model is used in the conformity analysis.23 When EPA announces a new emissions
model, such as MOVES5, we establish a grace period before the model needs to be used
for transportation conformity purposes (40 CFR 93.111(b)). In consultation with DOT,
EPA must consider several factors when establishing a grace period for conformity
determinations, including the degree of change in the emissions model and the effects of
the new model on the transportation planning process (40 CFR 93.111(b)(2)).
20 "Maintenance areas" are those areas that were initially designated nonattainment for a criteria pollutant
and subsequently redesignated to attainment after 1990. Maintenance areas have SIPs developed under
CAA section 175A. (40 CFR 93.101).
21 See footnote 2.
22 The grace period also applies in the case that a regional emissions analysis is done for a project not from
a conforming transportation plan and TIP (i.e., a project in an isolated rural area). See the transportation
conformity rule at 40 CFR 93.101 for the definition of an isolated rural area and 40 CFR 93.109(g) for how
conformity is done in an isolated rural area.
23 EPA notes that in the case of 1997 ozone NAAQS orphan areas, regional emissions analyses are not
required for that NAAQS. See the Transportation Conformity Guidance for the South Coast II Court
Decision for additional information.
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EPA encourages state and local agencies to use the latest version of the MOVES model
available at the time that any conformity modeling begins, so that users can take
advantage of the latest information and improvements included in the model.
3.3 Does the release of MOVES 5 with a new conformity grace period
affect the previous conformity grace period established when
MOVES4 was released?
The previous conformity grace period established when MOVES4 was released is
unaffected by the release of MOVES5. The MOVES5 conformity grace period is
separate and distinct from the two-year conformity grace period established with the
release of the previous version of the model, MOVES4. The two-year grace period
established by EPA's September 2023 MOVES4 Notice of Availability in the Federal
Register is unchanged by the release of MOVES5 and continues to be in effect until
September 12, 2025. 24
For more information on the MOVES4 conformity grace period, please see the
September 2023 Federal Register note and Section 3.10 on this guidance.
3.4 Under what circumstances will the MO VES5 grace period for
regional emissions analyses be shorter than two years?
As noted previously, EPA intends to include in the Federal Register notice a two-year
grace period for using MOVES5 for regional transportation conformity purposes and a
two-year grace period for project-level conformity purposes. Under that approach, the
MOVES5 conformity grace period for regional emissions analyses would end two years
after we publish the Federal Register notice announcing MOVES5, unless new
MOVES5-based SIP budgets become effective sooner. In such a case, once these new
MOVES5-based approved or adequate budgets become effective, the grace period can no
longer be used for that specific area and pollutant. Instead, the new regional emissions
analysis for that pollutant must use MOVES5 if the conformity determination is
demonstrating consistency with a MOVES5-based budget under 40 CFR 93.118. The
interagency consultation process must be used to develop any SIP revision based on
MOVES4 (40 CFR 93.105(b)(1)).
It is possible that areas that are designated nonattainment or maintenance for more than
one pollutant may rely on both MOVES5 and MOVES4 to determine conformity for
different pollutants during the MOVES5 grace period. For example, if a state revises a
previously submitted (but not approved) MOVES4-based PM10 SIP with MOVES5 and
24 See EPA's Notice of Availability, "Official release of the MOVES4 Motor Vehicle Emissions Model for
SIPs and Transportation Conformity," published in the Federal Register on September 12, 2023 (88 FR
625671.
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EPA finds these revised M0VES5 budgets adequate for conformity, such budgets would
apply for conformity on the effective date of the Federal Register notice announcing
EPA's adequacy finding. In this example, if an area was in nonattainment for PM10 and
ozone, the MOVES5 grace period would end for PM10 once EPA found the new
MOVES5- based SIP budgets adequate. However, MOVES4 could continue to be used
for ozone conformity determinations until the end of the MOVES5 grace period for
regional emissions analyses.25
In addition, in most cases, if the state revises previously approved budgets based on an
earlier EPA emissions model with MOVES5, the revised MOVES5 budgets could not be
used for conformity purposes until EPA approves them, i.e., approves the SIP revision.
In general, budgets in submitted SIPs cannot supersede approved budgets until the
submitted SIP is approved. See 40 CFR 93.118(e)(1).
However, 40 CFR 93.118(e)(1) allows an approved budget to be replaced by an
adequate budget if 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. In such cases, the MOVES5-based budgets
would be used for conformity purposes once they have been found adequate, if
requested by the state in its SIP submission and if specified in EPA's SIP approval.
States should consult with their EPA Regional Office to determine if this flexibility
could be applied to their situation.
3.5 How will the MOVES5 conformity grace period be implemented for
regional emissions analyses?
During the MOVES5 grace period, areas should use interagency consultation to examine
how MOVES5 will impact their regional emissions analyses and future transportation
plan and TIP conformity determinations. Isolated rural areas should also consider how
future regional emissions analyses will be affected when MOVES5 is required, if such an
analysis is anticipated. Areas should carefully consider whether the SIP and budget(s)
should be revised with MOVES5 or if transportation plans and TIPs should be revised
before the end of the conformity grace period, since doing so may be necessary to ensure
conformity in the future.
The conformity rule provides flexibility for analyses that are started before the Federal
Register Notice of Availability for MOVES5 is published or during the grace period.
Regional emissions analyses that are started during the grace period can use either
MOVES5 or MOVES4 (40 CFR 93.111(c)). Interagency consultation should be used if it
is unclear if a MOVES4-based analysis was begun before the end of the grace period.
25 In this example, such an area would use MOVES5 to develop a regional emissions analysis for
comparison to the revised MOVES5-based budgets (e.g., PM10 and NOx budgets in the PM10 SIP). The
regional emissions analysis for ozone could be based on MOVES4 for the VOC and NOx budgets in the
ozone SIP for the remainder of the conformity grace period.
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When the M0VES5 grace period ends, MOVES5 will replace MOVES4 as the current
EPA motor vehicle emissions model for transportation conformity purposes in states
outside California. In general, this means that all new regional emissions analyses started
after the end of the grace period must be based on MOVES5, even if the SIP is based on a
previous EPA emissions model (40 CFR 93.111). As discussed above, the grace period
for new regional emissions analyses would be shorter for a given pollutant if an area
revised its SIP and budgets with MOVES5 and such budgets were approved or found
adequate for conformity purposes prior to the end of the grace period.
Also, when the grace period ends, conformity determinations cannot rely on a previous
emissions analysis, as allowed by 40 CFR 93.122(g), that was prepared using MOVES4
because of the requirement in 40 CFR 93.111.
As discussed in more detail in the MOVES Technical Guidance, MOVES allows for
multiple approaches in developing a regional emissions analysis, which may result in
small differences in results.26 EPA recommends that the same approach be used in any
analysis that compares two or more cases (e.g., the SIP budget and the regional emissions
analysis for transportation conformity). Per 40 CFR 93.105(c)(l)(i), interagency
consultation must be used to evaluate and choose model(s) and associated methods and
assumptions for conformity determinations. If different approaches are used for the SIP
budget and the regional emissions analysis for practical reasons, interagency consultation
should be used to determine how to address (and minimize) any differences in results.
The methods used to develop inventories should be fully documented in the SIP and
conformity determination.
3.6 When will the use of MOVES5 be required for hot-spot analyses in
project-level conformity determinations?
The Federal Register notice that announces the availability of MOVES5 for official
purposes will establish the grace period for both regional emissions analyses and hot-spot
analyses. The structure of MOVES5, including at the Project Scale, is fundamentally the
same as MOVES4, although there are new data within the model. Hot-spot analyses are
required to be included in conformity determinations for all non-exempt Federal
Highway Administration (FHWA)/Federal Transit Administration (FTA) projects in CO
areas, and for "projects of air quality concern" in PM2.5 and PM10 nonattainment and
maintenance areas.27
Section 176(c)(1) of the CAA requires conformity determinations to be based on "the
most recent estimates of emissions." Additionally, the transportation conformity rule (40
CFR 93.111) requires conformity determinations to be based on "the latest emissions
estimation model available," and further states that this requirement is satisfied if the
most current version of EPA's motor vehicle emissions model is used in the conformity
26 See Section 1.4 for reference information for the MOVES Technical Guidance.
27 See 40 CFR 93.116 and 93.123 for more information.
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analysis. When EPA announces a new emissions model, such as MOVES5, we establish
a grace period before the model needs to be used for transportation conformity purposes
(40 CFR 93.111(b)). In consultation with DOT, EPA must consider the degree of change
in the emissions model and the effects of the new model on the transportation planning
process (40 CFR 93.111(b)(2)).
Once EPA announces the availability of MOVES5 in the Federal Register, MOVES5
will be the latest EPA motor vehicle emissions model for new conformity hot-spot
analyses outside of California and will need to be used in new analyses that begin after
the grace period ends. The MOVES5 grace period for conformity hot-spot analyses
applies to the use of MOVES5 and any future minor revisions that occur during the grace
period.
3.7 How will the MOVES 5 grace period be implemented for CO, PM ia
and PM2.5 hot-spot analyses?
Sections 93.116 and 93.123 of the transportation conformity regulations contain the
requirements for when a hot-spot analysis is required for project-level conformity
determinations.28 In addition, the conformity regulation provides flexibility for analyses
that are started before the end of the grace period. A conformity determination for a
transportation project may be based on a previous model if the analysis was begun before
or during 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
(40 CFR 93.111(c)).
Thus, under 40 CFR 93.111(c), for CO, PM10 and PM2.5 hot-spot analyses that start
during the MOVES5 grace period, project sponsors can choose to use MOVES4 or
MOVES5, since both are available during the grace period.
Per 40 CFR 93.105(c)(l)(i), interagency consultation must be used to evaluate and
choose model(s) and associated methods and assumptions for conformity determinations.
This includes which MOVES version to use for a hot-spot analysis. Project sponsors
should use the consultation process to determine which option may be most appropriate
for a given situation.
Any new CO, PM10, or PM2.5 hot-spot analyses for conformity purposes begun after the
end of the MOVES5 grace period must be based on MOVES5, per 40 CFR 93.111.
EPA guidance on how to use MOVES for CO and PM hot-spot analyses is available (see
Section 1.4). See EPA's Project-Level Conformity and Hot-Spot Analyses website for
latest information and guidance on how to conduct CO, PM10 and PM2.5 hot-spot
modeling for transportation conformity purposes.
28 In CO nonattainment and maintenance areas, a hot-spot analysis is required for all non-exempt projects,
with quantitative hot-spot analyses being required for larger, congested intersections and other projects (40
CFR 93.123(a)(1)). In addition, the conformity rule requires that a quantitative PM10 or PM2 5 hot-spot
analysis be completed for certain projects of local air quality concern (40 CFR 93.123(b)(1)).
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The length of the MOVES5 grace period for hot-spot analyses would not be affected by
an early submission of MOVES5-based SIP budgets. Using the same example as
described in Section 3.4, the two-year grace period would apply for PMio hot-spot
analyses even if approved or adequate MOVES5-based budgets for PMio are available
before it ends.
Please consult with your EPA Regional Office if there are questions about which model
should be used in a project-level conformity determination.
3.8 How will MOVES5 affect FHWA's CO categorical hot-spot finding?
FHWA released an updated CO categorical hot-spot finding for intersection projects in
January 2023 that was based on MOVES3.29 Until September 12, 2025, a project
sponsor may continue to rely on the categorical finding for applicable projects that are
determined through interagency consultation to be covered by the finding's parameters.
However, any new CO hot-spot analyses for conformity purposes begun after September
12, 2025, may no longer rely on the January 2023 CO categorical hot-spot finding
because the finding was based on MOVES3. See Section 3.10 for additional information
about the MOVES4 grace period.
3.9 How will MOVES5 affect CO hot-spot protocols that were previously
approved into the SIP?
Section 40 CFR 93.123(a)(1) of the transportation conformity regulation allows areas to
develop alternate procedures for localized CO hot-spot analyses, when developed through
interagency consultation and approved by the EPA Regional Administrator. Some states
have chosen in the past to develop such procedures based on previously approved EPA
emissions models.
During the MOVES5 grace period, areas with previously approved CO hot-spot protocols
based on MOVES4 may continue to rely on these protocols. Once the MOVES5 grace
period ends, new CO hot-spot analyses for conformity purposes will need to be based on
MOVES5 and thus may no longer rely on CO hot-spot protocols based on MOVES4 or
earlier versions.
3.10 When does the MOVES4 conformity grace period end?
As discussed in Section 3.3, the previous conformity grace period established when
MOVES4 was released is unaffected by the release of MOVES5. The MOVES4 grace
period ends September 12, 2025. Therefore, if areas do not yet have MOVES4 or
29 For more information, see the "CO Hot-Spot Analyses: FHWA Categorical Finding" heading on EPA's
Project-Level Conformity and Hot-Spot Analyses website.
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M0VES5-based budgets, M0VES3 could be used for a transportation conformity
determination that includes a regional emissions analysis where the analysis is begun on
or before September 12, 2025, per the transportation conformity regulation at 40 CFR
93.111(c). MOVES3 could also be used for a transportation conformity determination
that includes a hot-spot analysis where the analysis is begun on or before September 12,
2025.
Figure 1 depicts the use of MOVES model versions for transportation conformity in the
near term. Note it is possible to skip the use of MOVES4 altogether for transportation
conformity and go directly from using MOVES3 to using MOVES5.
2025
2026
2027
Figure 1: Use of MOVES Versions in Transportation Conformity Analyses
Per 40 CFR 93.105(c)( 1 )(i), interagency consultation must be used to evaluate and
choose model(s) and associated methods and assumptions for conformity determinations.
This includes which MOVES version to use for a transportation conformity
determination that includes a regional emissions analysis or a hot-spot analysis. If your
area intends to use MOVES3 for a transportation conformity analysis, please refer to the
MOVES4 Notice of Availability in the Federal Register (88 FR 62567) for more
information.30 Modelers are encouraged to check with the relevant EPA Regional
contact for transportation conformity (see Section 1.1) prior to beginning any MOVES3
model runs for transportation conformity purposes.
311 See EPA's Notice of Availability, "Official release of the MOVES4 Motor Vehicle Emissions Model for
SIPs and Transportation Conformity," published in the Federal Register on September 12, 2023 (88 FR
62567).
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Section 4. Using MOVES5 in General Conformity
4.1 When will the use of MOVES5 be required under the General
Conformity Rule?
Clean Air Act (CAA) section 176(c)(4)(A) requires EPA to establish criteria and
procedures for determining conformity for federal activities, which are defined as work
(e.g., construction, operations, etc.) not otherwise defined as transportation plans,
programs, or projects under 40 CFR part 93 subpart A (§93.102(a)). The general
conformity provisions are implemented under 40 CFR part 93, subpart B and require
federal agencies to work with state, tribal, and local governments to assure federal
activities that cause emissions to originate within nonattainment or maintenance areas
will not interfere with (i.e., will conform to) the air quality plans established in the
applicable implementation plan.31'32
When a federal agency is required to predict motor vehicle emissions to include in its
general conformity applicability analysis, the analysis must be prepared according to the
requirements at 40 CFR 93.159(b)(1).33 When EPA updates its motor vehicle emissions
model, a grace period of at least three months applies unless EPA announces a longer
grace period for the model, which may be as long as 24 months. EPA intends to specify a
two-year grace period for MOVES5 in its Federal Register Notice of Availability and
that same grace period applies for general conformity analyses under 40 CFR
93.159(b).34
As noted in Section 1.1, the MOVES5 grace period is separate and distinct from the
MOVES4 grace period. The two-year grace period established by EPA's September
2023 MOVES4 Notice of Availability in the Federal Register is unchanged by the
release of MOVES5 and continues to be in effect until September 12, 2025.
If the federal agency considers EPA's most current specified motor vehicle emissions
model to be inappropriate for their project, the agency may, at its discretion and as
allowed under 40 CFR § 93.159(b), obtain written approval from the appropriate EPA
Regional Administrator to use a modified version of the MOVES model or an approved
substitute model. The use of a modified or substitute model will be approved only on a
case-by-case basis, or where appropriate, on a generic basis for a specific federal agency
program.
31 See 40 CFR 93.155 and 93.156 for General Conformity reporting and public participation requirements.
32 See 40 CFR 93.152 definition of Applicable implementation plan.
33 See 40 CFR 93.152 definition of Applicability analysis.
MSee 40 CFR 93.111(b)(1).
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Section 5. Using MOVES5 for Other Purposes
5.1 Can MOVES5 be used to estimate greenhouse gas emissions?
Yes, M0VES5 is currently the best tool EPA has for estimating GHG emissions from the
transportation sector and is a significant improvement over MOVES4. As described in
Section 1.3, MOVES5 incorporates new emissions standards not included in MOVES4,
improved emission algorithms and data, and updated vehicle activity and population
inputs. In MOVES5, emissions of CO2 are lower in both the short and long term because
of new regulations. EPA notes that there are no SIP and transportation conformity
requirements for GHG emissions.
State, local, and tribal agencies should consider using the latest version of MOVES for
from the transportation sector, such as for GHG analyses related to the transportation
planning process or for Bipartisan Infrastructure Law and Inflation Reduction Act grant
programs. For example, MOVES is one of several tools available for use for GHG and
co-pollutant analyses under EPA's Climate Pollution Reduction Grants program.35
EPA has developed technical guidance36 that describes how to use MOVES to estimate
GHG emissions and/or energy consumption from onroad vehicles in a state or
metropolitan area. EPA's MOVES Hands-on Training also includes a module on
modeling GHG emissions that reflects the guidance. See Section 1.4 for reference
information for both the MOVES GHG Guidance and Hands-on Training.
5.2 Can MOVES5 be used to estimate mobile source air toxics (MSATs) ?
Yes, MOVES5 estimates emissions for MSATs such as benzene, 1,3-butadiene,
formaldehyde, acetaldehyde, acrolein, naphthalene, and ethylbenzene.37 MOVES5 is
EPA's best available tool for quantifying emissions of these MSATs. State and local
agencies, academic institutions, and other interested parties who are interested in
analyzing MS AT emissions from transportation projects should consider using the latest
version of MOVES.
EPA notes that there are no SIP and transportation conformity requirements for air toxics.
Regarding the analysis of MS AT emissions in the National Environmental Policy Act
(NEPA) process, DOT (or where DOT has assigned the role, the state DOT) has
responsibility for implementing NEPA for federally funded or approved transportation
projects.
35 For more information about these grants, please see EPA's Climate Pollution Reduction Grants website.
36 The latest version of Using MOVES for Estimating State and Local Inventories of On-Road Greenhouse
Gas Emissions and Energy Consumption is available on EPA's website at www.epa. gov/state-and-local-
transportation/estimating-greenhouse-gas-emissions.
37 More information, including a list of the mobile source air toxics in MOVES, can be found in EPA's
report, Air Toxic Emissions from Onroad Vehicles in MOVES5, available at www.epa. gov/moves/moves-
onroad-technical-reports.
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5.3 What role will MO VES5 play in EPA's National Emissions
Inventory?
EPA will use the latest released version of MOVES available at the time of the 2023
National Emissions Inventory (NEI) development to compute the 2023 NEI emissions.
The NEI is updated with state, local, and tribal submissions once every three years.38 The
most recent NEI as of the date on the cover of this document is the 2020 NEI. Mobile
source emissions for the 2020 NEI were generated with MOVES4 using a mix of EPA
and state-provided inputs. For more information, please refer to EPA's National
Emissions Inventory (NEI) website.
38 NEI on-road emissions for California are based on California's EMFAC model.
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