The Environmental Protection Agency (EPA) is approving portions and disapproving portions of a state implementation plan (SIP) revision submitted by the State of Colorado to meet Clean Air Act (CAA) requirements for the 2008 8-hour ozone national ambient air quality standards (NAAQS) in the Denver Metro/North Front Range nonattainment area (DMNFR Area). Specifically, the EPA is approving the submitted enhanced monitoring SIP element as meeting applicable Serious area requirements for the 2008 8-hour ozone NAAQS, and is disapproving the contingency measure element of the SIP submittal.

The Environmental Protection Agency (EPA) is disapproving certain portions of a state implementation plan (SIP) revision submitted by the State of Delaware, through the Delaware Department of Natural Resources and Environmental Control (DNREC), on November 22, 2016. The revision was submitted by Delaware in response to a national finding of substantial inadequacy and SIP call published on June 12, 2015, which included certain provisions in the Delaware SIP related to excess emissions during startup, shutdown, and malfunction (SSM) events.

The Environmental Protection Agency (EPA) is finalizing approval of a State Implementation Plan (SIP) revision submitted by the State of South Carolina, through the South Carolina Department of Health and Environmental Control (hereinafter referred to as SC DHEC or South Carolina) via a letter dated February 3, 2022. The SIP revision updates portions of South Carolina's Prevention of Significant Deterioration (PSD) and Nonattainment New Source Review (NNSR) regulations that pertain to Project Emissions Accounting (PEA) provisions.

On September 21, 2022, the Commonwealth of Kentucky, through the Kentucky Energy and Environment Cabinet (Cabinet), Division of Air Quality (DAQ), submitted a request for the Environmental Protection Agency (EPA) to redesignate the Northern Kentucky portion (hereinafter referred to as the ``Northern Kentucky Area'' or ``Area'') of the Cincinnati, Ohio- Kentucky, 2015 8-hour ozone nonattainment area (hereinafter referred to as the ``Cincinnati, OH-KY Area'') to attainment for the 2015 8-hour ozone National Ambient Air Quality Standards (NAAQS or standards) and to approve a State Implementati