Air Plan Approval; Mississippi; Infrastructure Requirements for the 2015 8-Hour Ozone National Ambient Air Quality Standards
The Environmental Protection Agency (EPA) is proposing to approve in part, and conditionally approve in part, a State Implementation Plan (SIP) submission provided by the State of Mississippi, through the Mississippi Department of Environmental Quality (MDEQ), through a letter dated January 25, 2021. This proposal pertains to certain infrastructure requirements of the Clean Air Act (CAA or Act) for the 2015 8-hour ozone national ambient air quality standards (NAAQS or standards). Whenever EPA promulgates a new or revised NAAQS, the CAA requires that each state adopt and submit a SIP for the implementation, maintenance, and enforcement of that NAAQS. The January 25, 2021, SIP submission addresses all infrastructure elements except for those pertaining to the contribution to nonattainment or interference with maintenance in other states. EPA is proposing to approve the January 25, 2021, SIP revision with the exception of the prevention of significant deterioration (PSD) infrastructure elements, the air quality modeling element, and the visibility protection element. EPA is proposing to conditionally approve the portions of the submittal related to the prevention of significant deterioration (PSD) infrastructure elements and the air quality modeling element. EPA will act on the visibility protection element in a separate rulemaking.