The Environmental Protection Agency (EPA) is taking final action to approve a revision to the State Implementation Plan (SIP) for the State of Missouri. This final action will amend the SIP to incorporate an additional sulfur dioxide (SO<INF>2</INF>) emissions limit for the Ameren Missouri (Ameren)--Sioux Energy Center (Sioux).

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 finalizing the approval of changes to the North Carolina State Implementation Plan (SIP), submitted by the State of North Carolina through the North Carolina Department of Environmental Quality (NCDEQ), Division of Air Quality (DAQ), through a letter dated April 13, 2021. This SIP revision includes changes to a subset of NCDEQ's regulations regarding emission control standards. EPA is approving these changes pursuant to the Clean Air Act (CAA or Act).

The Environmental Protection Agency (EPA) is approving a State Implementation Plan (SIP) revision submitted by the State of South Carolina, through the South Carolina Department of Health and Environmental Control (SC DHEC), on November 4, 2016. This revision was submitted by South Carolina in response to a finding of substantial inadequacy and SIP call published by EPA on June 12, 2015, of provisions in the South Carolina SIP related to excess emissions during startup, shutdown, and malfunction (SSM) events.