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Last Updated: Tuesday, April 30, 2013 8:13 AM
Air quality analysts usually use the models and guidance documents described below for transportation projects in California. Many are from external agencies including: U.S. Environmental Protection Agency , California Air Resources Board , or a local air pollution control or air quality management district .
Climate Change or Greenhouse Gas analysis may use air quality models in some cases, but other types of analysis are often preferred. See the Climate Change page at this site for more information.
EPA UPDATED CAL3QHCR ON 12/20/2012 AND AERMOD ON 12/10/2012. Always check the EPA and ARB web sites for updated versions of their models when starting project analysis. The updated version of CAL3QHCR has similar capabilites to the one offered by FHWA as part of the Quantitative PM Analysis training given by EPA in 2011 and early 2012.
- EPA Qualitative and Quantitative Analysis Guidance - see EPA Conformity Policy Guidance web page
EPA's 2010 Quantitative Analysis Guidance requires use of one of the following dispersion models. CALINE4 is not used for conformity-related PM10 or PM2.5 hot spot modeling.
- AP-42 for Paved Roads (EPA - see 13.2.1) | Statewide (ARB) | San Joaquin Valley (ARB) | Bay Area (not SIP-approved))
The latest EPA revision for Paved Road dust should be used statewide. Silt loading factors by county from the Statewide ARB method may be used with the newer EPA version.
For regional analysis using AP-42, freeway emissions are commonly scaled by centerline miles, rather than by lane miles as for other types of roads; however, this procedure has not yet been fully documented, tested, and accepted by EPA for project-level use. Use of centerline mile scaling helps to adjust for the lower-than-average silt loading found on heavily used roads where most dust remains suspended. The PM10 or (in some areas) PM2.5 SIPs may provide additional local guidance regarding use of this method.
- "Appendix W" (EPA's basic regulations regarding air quality modeling)
Construction Emission Analysis
The SER currently describes a qualitative approach for construction-stage (short term) air quality analysis.. In some cases, analysts may wish to quantify emissions. No single tool is suitable for use statewide for all types of projects, but these may be helpful as starting points:
- The current version of the Sacramento AQMD Road Construction Model is available from the AQMD's CEQA Tools web page.
- OFFROAD emission inventory model and procedures
- CalEEMod land development emission model
Replaces URBEMIS; update to use EMFAC 2011 is in progress. CalEEMod is not ideal for road construction emission analysis – it is oriented mainly at general land development analysis.
- Chapter 11 (Air Quality)
- Chapter 13 (Energy/Climate Change)
- Chapter 38 (NEPA Delegation - see Air Quality section)