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Mobile Sources Air Toxics Protocol



The Mobile Sources Air Toxics Protocol (MSAT Protocol) provides guidance to local land use jurisdictions on assessing and disclosing potential cancer risk and PM2.5 concentrations from major roadways and railways.  The Sac Metro Air District's Board of Directors approved the MSAT Protocol on January 25, 2018.  The MSAT Protocol replaces the Recommended Protocol for the Evaluation of Sensitive Receptors Adjacent to Major Roadways

The MSAT Protocol includes a risk mapping tool, a guidance document, a detailed methodology document, and is complemented by guidance on exposure reduction measures.  Links to each component of the MSAT Protocol can be found below.

The mapping tool does not reflect existing features on or adjacent to the location of interest that may reduce reported risk such as barriers, tree plantings, or enhanced indoor air filtration.  The presence or planning of those features should be accounted for by a jurisdiction's analysis when using the mapping tool.

Documents and Links 


MSAT Protocol Documents

Guidance Document for the Mobile Sources Air Toxics Protocol (April 2019)

Methodology/Technical Appendix (July 2018)


Mapping Tool


Exposure Reduction Guidance 

NEW Sac Metro Air District updated its Landscaping Guidance for Improving Air Quality Near Roadways (May 2020) to address allergens and climate change resiliency.  The first version from April 2017 is also available for reference.

California Air Resources Board's Air Filter FAQs

Sac Metro Air District's Portable Air Cleaner Air Exchange Rate Tool (July 2018)  This is a .zip file. Please save it and then open it to extract the .xlsm file.

California Air Resources Board's Strategies to Reduce Air Pollution Exposure Near High Volume Roadways: Technical Advisory 


Superceded Roadway Protocol

The Sac Metro Air District will continue to provide access to the superceded Roadway Protocol for historical reference. 

For More Information

Contact Rachel DuBose at or 916-874-4876.

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