EPA is taking direct final action to approve a revision to the Tennessee State Implementation Plan (SIP), submitted to EPA on December 13, 2012, by the State of Tennessee, through the Tennessee Department of Environment and Conservation (TDEC). Tennessee's December 13, 2012, SIP revision includes changes to the maintenance plan for the Knox County 1-hour ozone area submitted on August 26, 1992, and approved by EPA on September 27, 1993, and a subsequent SIP revision approved by EPA on August 5, 1997. The Knox County 1-hour ozone area was comprised of Knox County in its entirety. The December 13, 2012 SIP revision proposes to increase the safety margin allocated to motor vehicle emissions budgets (MVEB) for nitrogen oxides (NO<INF>X</INF>) and volatile organic compounds (VOC) for Knox County to account for changes in the emissions model and vehicle miles traveled (VMT) projection model. EPA is approving this SIP revision because the State has demonstrated that it is consistent with the Clean Air Act (CAA or Act).