The Environmental Protection Agency (EPA) is finalizing the approval of a State Implementation Plan (SIP) revision, submitted by North Carolina on April 13, 2021. Specifically, EPA is approving updates to the incorporation by reference of Federal new source review (NSR) regulations and federal guidelines on air quality modeling in the North Carolina SIP. EPA is also converting a previous conditional approval regarding the infrastructure SIP prevention of significant deterioration (PSD) elements, for the 2015 ozone national ambient air quality standards (NAAQS) for North Carolina to a full approval. EPA is also approving updates to North Carolina's NSR regulations to better align them with the federal rules. EPA is approving these changes pursuant to the Clean Air Act (CAA or Act).