Questions and Answers

EPA’s Approval of the MOVES2010a 

and EMFAC2007 Emissions Models 

for Transportation Conformity 

Hot-Spot Analyses, and Availability 

of Modeling Guidance: 

Questions and Answers 

1. What action is EPA taking in today’s Federal Register notice? 

In today’s Federal Register notice, EPA is approving the latest version of the Motor 

Vehicle Emissions Simulator model (MOVES2010a) for official use for quantitative 

carbon monoxide (CO) and particulate matter (PM2.5 and PM10) hot-spot analyses 

for transportation conformity purposes outside of California. EPA is also approving 

the latest version of the California EMission FACtor model (EMFAC2007) for quantitative PM hot-spot analyses for transportation conformity purposes within California. 

EPA is also announcing a two-year transportation conformity grace period before use 

of these models for these purposes is required. 

While EPA is approving the MOVES2010a and EMFAC2007 models for projectlevel transportation conformity purposes, today’s notice is applicable to current and 

future versions of the MOVES and EMFAC models, unless EPA notes otherwise 

when approving the models for conformity purposes. 

Finally, the notice announces the availability of two new EPA guidance documents 

for: (1) completing quantitative PM hot-spot analyses using MOVES, EMFAC, and 

other models, and (2) completing project-level CO analyses using MOVES. 

The Federal Register notice, guidance documents, a fact sheet, and other documentation are available online at the EPA website: www.epa.gov/otaq/stateresources/transconf/policy.htm. EPA and the Department of Transportation (DOT) will provide 

outreach and training for using the guidance documents. 

Office of Transportation and Air Quality 

EPA-420-F-10-062 

December 2010 
 

2. What is transportation conformity and what is a hot-spot analysis? 

Questions and Answers

Transportation conformity is a Clean Air Act requirement that ensures that federally supported 

highway and transit project activities are consistent with (“conform to”) the state air quality 

implementation plan (SIP). Conformity ensures that public health is protected by early consideration of the air quality impact of transportation decisions in cities with air quality challenges. 

Transportation conformity is required in nonattainment and maintenance areas for transportation-related criteria pollutants and national ambient air quality standards (NAAQS) (PM2.5, 

PM10, ozone, CO, and nitrogen dioxide). A “hot-spot analysis” allows for the local air quality 

impacts of a project to be considered before the project receives federal funding or approval. 

3. For what purposes are these models being approved? 

In today’s notice, EPA is approving the MOVES2010a model for official use for completing 

quantitative CO, PM2.5 and PM10 hot-spot analyses for transportation conformity purposes 

(with a grace period – see Question #4). EPA previously approved MOVES2010 for use in SIPs 

and transportation conformity regional emissions analyses in March 2010. MOVES2010a is a 

minor update to the original MOVES2010 model. 

Today EPA also is approving EMFAC2007 for official use when completing quantitative PM 

hot-spot analyses for transportation conformity purposes within California (also with a grace 

period – see Question #4). EPA previously approved EMFAC2007 for use in SIPs, regional 

emissions analyses, and quantitative CO hot-spot analyses in January 2008. Nothing in today’s 

action affects that approval. 

4. Is there a grace period for using these models for quantitative hot-spot analyses? 

Today’s Federal Register notice announces a two-year grace period before (1) the MOVES2010a 

emissions model is required to be used in quantitative CO and PM hot-spot analyses for transportation conformity purposes, and (2) the EMFAC2007 model is required to be used for PM 

hot-spot analyses for transportation conformity purposes within California. 

During the grace period in PM areas, the requirement to conduct qualitative analyses will 

continue to apply, using previously issued joint EPA-Federal Highway Administration (FHWA) 

guidance on such analyses. New quantitative PM hot-spot analyses started after the conclusion 

of the grace period must use MOVES2010a or EMFAC2007 (within California). See Question 

#5 for more on the quantitative PM hot-spot analysis guidance also released today. 

During the grace period in CO areas outside of California, project sponsors will have the option 

to use either MOVES2010a or EPA’s MOBILE6.2 model. New quantitative CO hot-spot analyses 

started after the conclusion of the grace period must use MOVES2010a. 

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Questions and Answers

5. What is the quantitative PM hot-spot guidance? 

Today’s notice includes the announcement that EPA’s final “Transportation Conformity Guidance for Quantitative Hot-spot Analyses in PM2.5 and PM10 Nonattainment and Maintenance 

Areas” is available. This is conformity guidance for modeling the local air quality impacts of 

certain transportation projects on the PM2.5 and PM10 NAAQS. 

This guidance describes how to complete quantitative hot-spot analyses for certain highway and 

transit projects in PM nonattainment and maintenance areas. This guidance describes conformity requirements for hot-spot analyses, and provides technical guidance on estimating project 

emissions with EPA’s MOVES model, California’s EMFAC model, and other methods. It also 

outlines how to apply air quality models for PM hot-spot analyses and includes additional references and examples. Finally, the guidance includes additional resources to assist state and local 

agencies in conducting quantitative PM hot-spot analyses. 

While this guidance addresses quantitative PM hot-spot analyses for transportation conformity 

purposes, certain sections of this guidance may be applicable when completing air quality analyses 

for transportation projects for other purposes. 

A draft of this guidance was made available for public comment on May 26, 2010 with a closing 

date of July 19, 2010 (75 FR 29537-29538). EPA received 15 sets of comments on the draft 

guidance and considered these comments when developing its final guidance. 

This guidance can be found on EPA’s web site at: www.epa.gov/otaq/stateresources/transconf/ 

policy.htm. 

6. What is the project-level CO guidance? 

Today’s notice also includes the announcement that EPA’s final guidance document “Using 

MOVES in Project-Level Carbon Monoxide Analyses” is available. This guidance describes 

how to use the MOVES emissions model to estimate CO emissions from transportation projects, 

including roadway intersections, highways, transit projects, parking lots and intermodal terminals. This guidance can be applied when using MOVES to complete any project-level quantitative CO analysis, including hot-spot analyses for transportation conformity determinations, 

modeling project-level emissions for SIP development, and completing analyses pursuant to 

the National Environmental Policy Act. This MOVES guidance applies in all states other than 

California. 

This guidance does not address air quality modeling for project-level CO analyses, as there are 

other existing resources that support CO project-level analyses. For example, EPA’s regulatory 

recommendations for CO air quality modeling can be found in Appendix W to 40 CFR Part 51. 

Users should also continue to consult the “1992 Guideline for Modeling Carbon Monoxide from 

Roadway Intersections,” (EPA-454/R-92-005, November 1992). 

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The new CO project-level MOVES guidance can be found on EPA’s web site at: www.epa.gov/ 

otaq/stateresources/transconf/policy.htm. 

Questions and Answers

7. How has EPA coordinated with other agencies and stakeholders on the actions taken in 

today’s notice? 

As required by the transportation conformity rule, EPA consulted with the FHWA and Federal 

Transit Administration (FTA) when establishing the two-year transportation conformity grace 

period described in today’s notice. 

EPA also coordinated with FHWA and FTA when developing the guidance documents released 

today. In addition, EPA worked with the California Air Resources Board (CARB) and the 

California Department of Transportation (Caltrans) to develop the portions of the PM hot-spot 

guidance relating to the use of CARB’s EMFAC model in California. 

Finally, EPA developed the guidance documents in coordination with state and local agencies 

and other stakeholder groups. EPA considered comments from conformity stakeholders when 

developing the final guidance documents. 

8. Who do I contact for more information? 

Any general questions regarding the actions taken today can be directed to Meg Patulski at: 

U.S. Environmental Protection Agency
 

Office of Transportation and Air Quality
 

Transportation and Regional Programs Division
 

(734) 214-4842
 

E-mail: patulski.meg@epa.gov
 

Technical questions about completing emissions and air quality modeling for hot-spot analyses 

can also be sent to: 

conformity-hotspot@epa.gov 

For specific questions concerning using the guidance documents for a project in a particular 

nonattainment or maintenance area, please contact the transportation conformity staff person 

responsible for your state at the appropriate EPA Regional Office. Contact information for EPA 

Regional Offices can be found at: 

www.epa.gov/otaq/stateresources/transconf/contacts.htm 

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