Federal air quality regulations require Metropolitan Planning Organizations (MPOs) to monitor air pollutants, including: ozone; particulate matter under 2.5 microns in diameter (PM 2.5); particulate matter under 10 microns in diameter (PM-10); and carbon dioxide (CO).
The San Joaquin Valley is currently designated as nonattainment with respect to Federal air quality standards for ozone and PM 2.5; and has a maintenance plan for PM-10, as well as a maintenance plan for CO for the urbanized/metropolitan areas of Kern, Fresno, Stanislaus, and San Joaquin Counties. As San Joaquin County's transportation planning agency, SJCOG is responsible for demonstrating that transportation plans and programs satisfy the requirements of the Clean Air Act.
The 2018 Air Quality Conformity Document outlines regulations concerning air quality and how those regulations affect the region's ability to deliver transportation projects. The Draft 2018 Air Quality Conformity Document was released for public review and comment on March 28, 2018.