On September 9, 2016, the Commonwealth of Kentucky, through the Kentucky Division for Air Quality (KDAQ), submitted a revision to the Kentucky State Implementation Plan (SIP). The Environmental Protection Agency (EPA) is proposing to approve changes to the Commonwealth's air quality standards for carbon monoxide (CO), lead (Pb), nitrogen dioxide (NO2), ozone, particulate matter (both PM10 and PM2.5), and sulfur dioxide (SO2) to reflect the historical and current National Ambient Air Quality Standards (NAAQS). EPA is proposing to approve this SIP revision because the Commonwealth has demonstrated that these change are consistent with the Clean Air Act (CAA or Act). KDAQ's submission also includes additional air quality standards for hydrogen sulfide, fluorides, and odor; however, EPA is not proposing to approve these state standards into the SIP. Written comments must be received on or before August 16, 2017. Further details may be found at the Federal Register.