Air Plan Approval; Mississippi; 2010 1-Hour SO2 NAAQS Transport Infrastructure
Key claim: EPA is proposing to approve Mississippi’s air plan after concluding the state’s sulfur dioxide emissions will not significantly worsen air quality in other states under the 2010 1-hour SO2 standard.
Abstract
(Proposed Rule · Environmental Protection Agency) Pursuant to the Federal Clean Air Act (CAA or the Act), the U.S. Environmental Protection Agency (EPA or Agency) is proposing to approve a State Implementation Plan (SIP) revision submitted by the State of Mississippi, through the Mississippi Department of Environmental Quality (MDEQ), on January 27, 2022, for the purpose of complying with the “good neighbor” provision of the CAA for the 2010 1-hour sulfur dioxide (SO2) primary National Ambient Air Quality Standard (NAAQS). The good neighbor provision requires each State’s implementation plan to contain adequate provisions prohibiting the interstate transport of air pollution in amounts that will contribute significantly to nonattainment, or interfere with maintenance, of a NAAQS in any other State. In this proposed rulemaking, the EPA is proposing to determine that Mississippi will not contribute significantly to nonattainment or interfere with maintenance of the 2010 1-hour SO2 primary NAAQS in any other State. Therefore, the EPA is proposing to approve the January 27, 2022, SIP revision as meeting the requirements of the good neighbor provision for the 2010 1-hour SO2 primary NAAQS.
Why this matters
Good neighbor SIP approvals under the 2010 1-hour SO2 NAAQS determine whether upwind states face additional emission-control obligations to protect downwind air quality. A proposed approval for Mississippi signals EPA’s view that the state’s existing SO2 sources — largely power generation and industrial boilers — do not warrant further transport-driven controls, avoiding new compliance costs while leaving downwind health protection to other mechanisms.