CARB submitted California’s Infrastructure State Implementation Plan revision for the 0.070 ppm 8-hour Ozone National Ambient Air Quality Standard on October 1, 2018. The U.S. Environmental Protection Agency approved California's 2018 Infrastructure State Implementation Plan on March 30, 2021, except for the Good Neighbor or Interstate Transport portion. On May 24, 2022, U.S. Environmental Protection Agency proposed disapproval of the Good Neighbor portion of the California’s 2018 Infrastructure State Implementation Plan which was finalized on February 2, 2023 and went into effect on March 15, 2023. On April 6, 2022, the U.S. Environmental Protection Agency proposed an Interstate Transport Federal Implementation Plan for California, which was finalized on June 5, 2023 and went into effect 60 days later on August 5, 2023.
The 2024 Transport State Implementation Plan Amendment (Good Neighbor SIP) has been prepared to resolve the disapproval and replace the Interstate Transport Federal Implementation Plan for California. This 2024 Good Neighbor SIP submission will address the inadequacies outlined by the U.S. Environmental Protection Agency in their disapproval and ensure that the emission reduction targets outlined in the Interstate Transport Federal Implementation Plan are addressed adequately. The 2024 Good Neighbor SIP includes approximately 65 tons per day of oxides of nitrogen (NOx) emission reductions statewide in 2026; associated with CARB’s recently adopted Clean Truck Check Program that significantly exceeds the almost 10 tons per day of NOx reductions in the Interstate Transport Federal Implementation Plan. This State Implementation Plan revision is critical to address interstate transport of ozone forming-pollutants. If adopted, CARB will submit the 2024 Good Neighbor SIP to the U.S. Environmental Protection Agency for inclusion into the California State Implementation Plan to resolve both the disapproval and the Interstate Transport Federal Implementation Plan.
