The Environmental Protection Agency (EPA) is taking final action to approve portions of State Implementation Plan (SIP) revisions submitted by the Commonwealth of Kentucky, through the Kentucky Division for Air Quality, on December 21, 2016, and August 29, 2017, on behalf of the Louisville Metro Air Pollution Control District (District). The changes to the SIP that EPA is taking final action to approve are the portions of the submittals that modify the District's Ambient Air Quality Standards regulation, specifically changes to the District's air quality standards for fine particulate matter (PM<INF>2.5</INF>) and ozone to reflect the 2012 PM<INF>2.5</INF> and 2015 ozone national ambient air quality standards (NAAQS). EPA has determined that the December 21, 2016, and August 29, 2017, SIP revisions are consistent with the Clean Air Act (CAA or Act). EPA will act on the other portions of the December 21, 2016, and August 29, 2017, submittals in a separate action.