Air Plan Approval; Pennsylvania; Redesignation of the Warren County Nonattainment Area to Attainment and Approval of the Area’s Maintenance Plan for the 2010 1-Hour Primary Sulfur Dioxide National Ambient Air Quality Standard
Key claim: EPA proposes to redesignate Warren County, Pennsylvania from nonattainment to attainment for the 2010 1-hour primary SO2 NAAQS, approve the area’s maintenance plan, and correct erroneous source-specific SIP requirements for United Refining Company.
Abstract
(Proposed Rule · Environmental Protection Agency) The Environmental Protection Agency (EPA) is proposing to approve a state implementation plan (SIP) revision and redesignation request submitted on September 19, 2025 by the Pennsylvania Department of Environmental Protection (PADEP). The SIP revision asks the EPA to redesignate the Warren County, Pennsylvania area from nonattainment to attainment for the 2010 1-hour primary sulfur dioxide (SO2) national ambient air quality standard (NAAQS). The revision also asks the EPA to approve into the SIP the Commonwealth’s maintenance plan for the 2010 1-hour primary SO2 NAAQS for the Warren County area. Furthermore, Pennsylvania requests that the EPA correct source- specific requirements for United Refining Company within the Pennsylvania SIP that were previously included in error. This proposed action is being taken under the Clean Air Act (CAA).
Why this matters
Redesignation to attainment for the 2010 1-hour SO2 NAAQS lifts nonattainment planning burdens on Warren County and formalizes a 10-year maintenance plan governing ongoing SO2 emissions, primarily from the United Refining Company facility. The action illustrates how EPA finalizes local air-quality improvements through source-specific SIP corrections rather than new national standards, with practical effects on permitting flexibility and industrial compliance costs in the area.