The Environmental Protection Agency (EPA) previously listed the Chattanooga region as a nonattainment area for one National Ambient Air Quality Standard (NAAQS) – the 1997 annual standard for particulate matter less than 2.5 micrometers in diameter (PM2.5). On October 24, 2016, EPA revoked the annual PM2.5 national ambient air quality standard for the Chattanooga, TN-GA-AL PM2.5 maintenance area. As of that date, there is no requirement for the region to demonstrate transportation conformity, including hot-spot analyses for the PM2.5 standard.

As a result of this action the TPO’s Interagency Air Quality Consultation Committee (IAC) was dissolved.  If you would like information related to the IAC, please contact TPO staff at

While no longer in nonattainment, the Chattanooga region remains eligible for the use of Congestion Mitigation and Air Quality Improvement (CMAQ) Program funds from the statewide PM2.5 set aside. The TPO continues to serve a role in advising member jurisdictions of the availability of these funds and eligible work types.