The Environmental Protection Agency (EPA) is approving the State Implementation Plan (SIP) submission, provided by the State of Tennessee, through the Tennessee Department of Environment and Conservation (TDEC), through a letter dated September 13, 2018, for inclusion into the Tennessee SIP. This action pertains to the infrastructure requirements of the Clean Air Act (CAA or Act) for the 2015 8-hour ozone national ambient air quality standard (NAAQS). Whenever EPA promulgates a new or revised NAAQS, the CAA requires that each state adopt and submit a SIP for the implementation, maintenance, and enforcement of each NAAQS promulgated by EPA. TDEC certified that the Tennessee SIP contains provisions that ensure the 2015 8-hour ozone NAAQS is implemented, enforced, and maintained in Tennessee. EPA has determined that portions of Tennessee's SIP submission satisfy certain required infrastructure elements for the 2015 8-hour ozone NAAQS.