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 Chattanooga/Hamilton County Air Pollution Control Bureau (Chattanooga/Hamilton County) on June 25, 2008. The changes to the SIP that EPA is taking final action to approve include changes to Chattanooga/Hamilton County's air quality standards for carbon monoxide, lead, nitrogen dioxide, particulate matter, ozone, and sulfur dioxide to reflect the current National Ambient Air Quality Standards (NAAQS). The portions of the SIP revision that EPA is approving are consistent with the requirements of the Clean Air Act (CAA or Act).