Jump to main content or area navigation.

Contact Us

State and Local Transportation Resources

Project-Level Conformity and Hot-Spot Analyses

Transportation
Conformity

NOTE: You will need Adobe Acrobat Reader, available as a free download, to view some of the files on this page. See EPA's PDF page to learn more about PDF, and for a link to the free Acrobat Reader.

This page contains policy guidance, technical guidance, and other resources issued by EPA to assist agencies in completing project-level conformity analyses, including particulate matter (PM2.5 and PM10) and carbon monoxide (CO) "hot-spot" analyses.

PM Hot-spot Analyses: Guidance

  • Transportation Conformity Guidance for Quantitative Hot-spot Analyses in PM2.5 and PM10 Nonattainment and Maintenance Areas
    EPA has released final guidance for modeling the local air quality impacts of certain transportation projects on the PM2.5 and PM10 national ambient air quality standards (NAAQS). This guidance is to be used by state and local agencies to conduct quantitative PM "hot-spot analyses" for new highway and transit projects that involve significant diesel emissions. This guidance describes how to estimate project emissions using EPA's MOVES model, California's EMFAC model, and other methods. It also outlines how to apply air quality models (such as AERMOD and CAL3QHCR) for PM hot-spot analyses. The guidance also includes a list of additional resources that may assist agencies in conducting quantitative PM hot-spot analyses. Update of November 2013: This guidance was originally released in December 2010, and Sections 5, 7.6, and 9.4 have been updated to reflect EMFAC2011 and EPA's 2012 PM NAAQS final rule. The November 2013 guidance supersedes the December 2010 guidance. Please refer to the fact sheet and guidance change bulletin below for more information.
    Contact: Meg Patulski at 734-214-4842 or patulski.meg@epa.gov
    Technical questions about this guidance can be directed to conformity-hotspot@epa.gov.

    The two-year grace period for completing quantitative hot-spot analyses using MOVES and EMFAC ended on December 20, 2012; new PM hot-spot conformity analyses required under 40 CFR 93.123(b)(1) started after this date must be quantitative rather than qualitative. See the Federal Register notice (PDF) and EPA's latest MOVES policy guidance for details.


  • Transportation Conformity Guidance for Qualitative Hot-spot Analyses in PM2.5 and PM10 Nonattainment and Maintenance Areas (PDF) (35 pp, 306K, EPA420-B-06-902, March 2006)
    The Environmental Protection Agency (EPA) and the Federal Highway Administration (FHWA) developed this guidance to help state and local agencies complete qualitative PM hot-spot analyses, when applicable.
    Contact: Meg Patulski at 734-214-4842 or patulski.meg@epa.gov

top of page

CO Hot-spot Analyses: Guidance

  • Using MOVES in Project-Level Carbon Monoxide Analyses (PDF) (59pp, 2M, EPA420-B-10-041, December 2010)
    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 NEPA analyses.
    Contact: Chris Dresser at 734-214-4637 or dresser.chris@epa.gov. Technical questions about this guidance can be directed to conformity-hotspot@epa.gov.
  • The two-year grace period for completing quantitative hot-spot analyses using MOVES and EMFAC ended on December 20, 2012; any new quantitative CO hot-spot conformity analyses started after this date outside of California must be based on MOVES. See the Federal Register notice (PDF) and EPA's latest MOVES policy guidance for details.

top of page

CO Hot-spot Analyses: FHWA Categorical Finding

  • CO Categorical Hot-Spot Finding for Intersection Projects
    On February 12, 2014, the Federal Highway Administration (FHWA) announced the availability of a carbon monoxide categorical hot-spot finding for certain projects involving a large urban intersection. Where a project’s parameters fit the conditions of the categorical hot-spot finding, project sponsors may be able to rely on the categorical hot-spot finding in place of doing their own CO hot-spot analysis as part of a project-level conformity determination in CO maintenance areas outside of California. The interagency consultation process should be used to determine whether the CO categorical hot-spot finding applies to a particular project, and any project-level conformity determination that relies on FHWA’s finding would be subject to public involvement requirements (40 CFR 93.105).

    See FHWA’s CO categorical hot-spot finding website for more information about the finding.  Questions about applicability of the finding can be addressed to the appropriate EPA Regional staff contact or Meg Patulski at 734-214-4842 or patulski.meg@epa.gov.

top of page

Emissions Models and Methods

top of page

Air Quality (Dispersion) Models

  • Recommended Air Quality (Dispersion) Models for PM Hot-spot Analyses
    The following is a summary of recommended air quality models for completing PM hot-spot analyses for different types of transportation projects. This is a reproduction of Exhibit 7-2 of the Quantitative PM Hot-spot Guidance.

    Type of Project Recommended Model(s)
    Highway and intersection projects AERMOD, CAL3QHCR
    Transit, freight, and other terminal projects AERMOD
    Projects that involve both highway/intersections and terminals, and/or nearby sources AERMOD

    See Section 7 of the guidance for complete information on selecting an appropriate air quality model. See below for which model versions are currently approved for regulatory use.

  • Approved Versions of Air Quality (Dispersion) Models
    The following is a summary of currently approved versions of air quality (dispersion) models for quantitative PM hot-spot analyses, as recommended by EPA's "Guideline for Air Quality Models" (Appendix W to 40 CFR Part 51). This is only a summary; refer to the appropriate guidance and model websites for more information about the applicability and use of these models. Draft or unapproved versions of models cannot be used to complete hot-spot analyses for regulatory purposes.

    Air Quality Model Version/date Link to Model Information
    AERMOD Version Dated 13350 www.epa.gov/ttn/scram/dispersion_prefrec.htm#aermod
    CAL3QHCR Version dated 13196 www.epa.gov/ttn/scram/dispersion_prefrec.htm#cal3qhc

top of page

Tools for Completing Project-level Analyses

  • Tool to generate EMISFACT portion of an AERMOD input file
    EPA has developed a MySQL script called "MOVES2AERMOD" to automate the process of generating the EMISFACT portion of an AERMOD input file using MOVES output. The tool is intended to be used as part of a quantitative PM hot-spot analysis and can be run directly through the MOVES GUI. To obtain the tool and for more information, see the MOVES tools page.
  • MySQL 24-hour PM2.5 Design Value Script
    EPA has developed a MySQL script to calculate design values for the 24-hour PM2.5 NAAQS for PM hot-spot analyses. The readme file in the download package describes how to "install" the tool as well as providing instructions on using it for PM hot-spot analyses. Update of September 2013:  This script was updated to eliminate a bug that occurred when modeling certain situations.

top of page

Training and Other Resources

  • Quantitative PM Hot-spot Analysis Training
    EPA and DOT have developed a three-day training course on implementing EPA's guidance. This technical, hands-on course is geared toward state and local agencies and focuses on using emission models (including EPA's MOVES model) and air quality models (AERMOD and CAL3QHCR) for quantitative PM hot-spot analyses. The PM hot-spot analysis training page provides the latest training materials and other information.
  • MOVES Model Information and Training
    • The EPA's MOVES page provides complete information about the model, including downloads, technical guidance, and tools.
    • The MOVES listserv provides updates on MOVES and other mobile source emissions models. Sign up here.
    • EPA has developed a two-day, hands-on course geared toward state and local agencies who will use MOVES for developing SIPs and regional conformity analyses, as well as a shorter web-based course for people interested in a general overview of MOVES. The MOVES training page contains information about this and other MOVES training information, courses, and webinars.
  • Air Quality Model Information
    • More information about dispersion models (including AERMOD and CAL3QHCR), meteorology preprocessors, and related tools, guidance, and outreach can be found on EPA's Support Center for Regulatory Atmospheric Modeling (SCRAM) website.
    • The SCRAM RSS feed provides updates on recent posting and additions to the SCRAM website. Sign up here.
  • Presentations
  • Additional conformity-related training information and presentations can be found at www.epa.gov/otaq/stateresources/transconf/training.htm.

top of page

Frequently Asked Questions (FAQs)

  • EPA FAQs
    The following are frequently asked questions about conducting hot-spot analyses for transportation conformity purposes. EPA will update these periodically.
  • Federal Highway Administration PM2.5 FAQs
    FHWA has developed a series of FAQs specifically for PM2.5 project-level conformity and hot-spot analyses. These FAQs were coordinated with EPA. The FHWA PM2.5 Project-Level Conformity and Hot-Spot Analyses FAQs webpage has more information.
  • Near Roadway Air Pollution and Health
    For answers to frequent questions concerning near roadway air pollution and what EPA is doing to address this important health concern, go to the Near Roadway Air Pollution and Health page.

top of page

Contact Information

  • EPA Regional Conformity Contacts
    EPA regional conformity staff are the primary EPA contacts for project sponsors completing project-level analyses for conformity purposes and should be contacted first for information and questions about these analyses. For the complete list of contacts by region, please see www.epa.gov/otaq/stateresources/transconf/contacts.htm.
  • Technical questions about using MOVES for project-level analyses can be directed to mobile@epa.gov.
  • Other technical questions on completing PM or CO project-level conformity analyses can be directed to conformity-hotspot@epa.gov.
  • EPA's Office of Air Quality Planning and Standards maintains a list of state air quality modeling staff who have experience that may be useful to a project sponsor when completing a hot-spot analysis, including running the selected air quality model and finding representative background data for a project. See OAQPS's state contacts page for more information.

top of page

This page is maintained by EPA's Office of Transportation and Air Quality (OTAQ).
For more: About Us | Get E-mail Updates | Browse the A to Z Subject Index.

Jump to main content.