The Environmental Protection Agency (EPA) is taking final action to approve changes to the Jefferson County portion of the Kentucky State Implementation Plan (SIP), submitted by the Commonwealth of Kentucky, through the Energy and Environment Cabinet (Cabinet), Division of Air Quality, through a letter dated September 5, 2019. 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). The SIP revision includes changes to Jefferson County Regulations regarding performance tests.