The Environmental Protection Agency (EPA) is approving changes to the Jefferson County portion of the Kentucky State Implementation Plan (SIP) submitted by the Commonwealth of Kentucky through the Kentucky Energy and Environment Cabinet (Cabinet) on May 31, 2023. The changes were submitted by the Cabinet on behalf of the Louisville Metro Air Pollution Control District (District, also referred to herein as Jefferson County). EPA is approving changes to the District's definitions rule to include a list of "trivial activities" in a new appendix; update the incorporation by reference date of the Federal air quality regulation that excludes certain organic compounds from the definition of "volatile organic compounds (VOC);" and make minor grammatical changes. This action is pursuant to the Clean Air Act (CAA or Act) and its implementing regulations.