The federal Clean Air Act (Act) establishes planning requirements for areas that exceed the health-based National Ambient Air Quality Standards. Areas are designated as nonattainment based on monitored exceedances of these standards. These nonattainment areas must develop an emission inventory as the basis of a State Implementation Plan (SIP) that demonstrates how they will attain the standards by specified dates.
In 2008, the United States Environmental Protection Agency (U.S. EPA) strengthened the ambient air quality standard for 8-hour ozone from 0.08 to 0.075 parts per million (ppm). Effective July 20, 2012, U.S. EPA completed area designations for the 2008 8-hour ozone standard with sixteen areas in California classified as marginal, serious, severe, or extreme nonattainment. The Act requires states and local governments to prepare baseline emission inventories for all areas exceeding the National Ambient Air Quality Standards within two years of designation.
2012 Baseline Emission Inventory
The Emission Inventory SIP Submittal has been compiled by CARB staff and reflects the most up-to-date emission inventory for all non-attainment areas. Since the Statewide attainment challenges for the national 8-hour standard occur in the summer months, the 2012 baseline summer season (May-October) planning emission inventories (tons/day) for nitrogen oxides (NOx) and volatile organic compounds (VOCs), the two precursors to ozone formation, have been compiled for the sixteen areas.
This SIP Submittal was approved by the CARB on June 26, 2014 and transmitted to U.S. EPA on July 17, 2014.