California Air Resources Board

The Mobile Source Emissions Inventory (MSEI) web site is CARB's central location for information about the population, activity, and emissions from mobile sources operating in California. Mobile sources include both on-road vehicles and off-road equipment such as construction equipment, marine vessels, locomotives, and aircraft. CARB’s mobile source inventories are periodically refreshed and revised to support air quality plans, transportation assessments, regulations, and other policies such as incentive programs. This MSEI web site is maintained by the Mobile Source Analysis Branch (MSAB) in the Air Quality Planning and Science Division.

For general inquiries or specific questions, please contact Mobile Source Emissions Inventory Support at msei@arb.ca.gov 

For a current listing of contacts for MSAB, please see the web page for the Organization of the California Air Resources Board for the Air Quality Planning and Science Division.