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Last Updated: Friday, February 22, 2013 9:54 AM
Emission factors that represent the vehicle fleet, speeds, and environmental conditions associated with a project are needed to perform project-level air quality modeling.The EMFAC model issued by the California Air Resources Board is used for this process in California. For more details regarding project-level "hot spot"modeling, please refer to the CO Protocol, Appendix B and the U.S. EPA's latest guidance for particulate matter hot spot analysis.
EMFAC 2011 was released by ARB on September 30, 2011. It has not yet been officially made available for conformity analysis purposes by U.S. EPA. Until EPA announces availability in the Federal Register, CONFORMITY ANALYSIS will continue to use EMFAC 2007. New air quality analysis for other purposes (not related to conformity analysis) may and should use the new version.
EMFAC 2007 is required for regional and project-level conformity studies (see FHWA letter, second page). U.S.EPA made EMFAC 2007 available for conformity use through a notice of availability in the Federal Register on January 18, 2008 (PDF or HTML file at EPA) . The grace period for completing project studies using EMFAC 2002 has expired.
All available versions of the EMFAC software can be found at the ARB web http://www.arb.ca.gov/msei/msei.htm .
The EMFAC model and all supporting data are provided and supported by the California Air Resources Board .
Caltrans and UC Davis interpreted the EMFAC 2007 model to provide a simplified user interface for project-level emission analysis, including emission factors and emission burden of criteria pollutants typically analyzed and Mobile Source Air Toxics (based on ARB's speciation factors for Total Organic Gases - TOG). For more information and to download the software package, see the CT-EMFAC page.
The current CT-EMFAC is based on EMFAC 2007, and should not be used for NEW environmental studies started after October 1, 2011. However, it may still be used for conformity-related studies until U.S. EPA makes EMFAC 2011 available for conformity analysis purposes and any grace periods set by EPA and FHWA expire. The web-interface and (new in January 2013) EMFAC 2011-PL versions of EMFAC 2011 can be used for project-level analysis pending a CT-EMFAC update.