EPA Actions Affecting Interstate Transport of Ozone

The Clean Air Act (CAA or Act) requires states to submit and implement State Implementation Plans (SIP) to address state air quality for each pollutant with a National Ambient Air Quality Standard (NAAQS) and mitigate any interstate transport of emissions that contribute significantly to nonattainment or interfere with maintenance of another state’s NAAQS (i.e., the “Good Neighbor” provision). Given that the transport of ozone and ozone precursors across state borders can impact air quality in downwind states, several states have stressed that the ozone transport from upwind states continues to exacerbate the difficulty of attaining the ozone standards. This issue brief explores the tools available to states to address interstate transport and recent actions by the Environmental Protection Agency (EPA or Agency) and courts to address Good Neighbor concerns.

UPDATE: This MJB&A Issue Brief has been updated to reflect several state legislative and regulatory actions that have occurred since the initial publication of this brief on January 14, 2019.