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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 (September 2020)

Methodology/Technical Appendix (July 2018)


Mapping Tool


Exposure Reduction Guidance 


Superceded Roadway Protocol

The Sac Metro Air District will continue to provide access to the superceded Roadway Protocol for historical reference. 

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