The Environmental Protection Agency (EPA) is updating a portion of the Outer Continental Shelf (OCS) Air Regulations. Requirements applying to OCS sources located within 25 miles of states' seaward boundaries must be updated periodically to remain consistent with the requirements of the corresponding onshore area (COA), as mandated by the Clean Air Act. The portion of the OCS air regulations that is being updated pertains to the requirements for OCS sources for which Massachusetts is the designated COA.

The Environmental Protection Agency (EPA) is approving a state implementation plan (SIP) revision submitted by the State of West Virginia. The revision updates West Virginia's incorporation by reference of EPA's national ambient air quality standards (NAAQS) and the associated monitoring reference and equivalent methods. EPA is approving these revisions to the West Virginia SIP in accordance with the requirements of the Clean Air Act (CAA).

The Environmental Protection Agency (EPA) is approving elements of a State Implementation Plan (SIP) submission from Indiana regarding the infrastructure requirements of section 110 of the Clean Air Act (CAA) for the 2015 ozone National Ambient Air Quality Standards (NAAQS). The infrastructure requirements are designed to ensure that the structural components of each state's air quality management program are adequate to meet the state's responsibilities under the CAA.

The Environmental Protection Agency (EPA) is approving a State Implementation Plan (SIP) revision submitted by the State of Tennessee on April 9, 2021. Specifically, EPA is approving updates to the incorporation by reference of Federal guidelines on air quality modeling in the Tennessee SIP. EPA is also converting the previous conditional approval regarding infrastructure SIP prevention of significant deterioration (PSD) elements for the 2015 ozone national ambient air quality standards (NAAQS) for Tennessee to a full approval.