The Environmental Protection Agency (EPA) is taking final action to approve a portion of a revision to the Chattanooga-Hamilton County portion of the Tennessee State Implementation Plan (SIP) submitted by the State of Tennessee through the Tennessee Department of Environment and Conservation (TDEC) on behalf of the Chattanooga- Hamilton County Air Pollution Control Bureau (Chattanooga-Hamilton County) on June 25, 2008. The revision amends the definition of "volatile organic compounds" (VOC) to be consistent with state and Federal regulations. The portion of the SIP revision that EPA is approving is consistent with the requirements of the Clean Air Act (CAA or Act). EPA will act on the other portions of the June 25, 2008, submittal in a separate action.