Air Quality Conformity

Air Quality Conformity

The Clean Air Act Amendments (CAAA) of 1990 and the federal transportation regulations and legislation recognized the major contributions of transportation sources to the overall air quality problem evidenced throughout the country. To effectuate a reduction in transportation-related emissions and a corresponding improvement in air quality, areas designated as non-attainment or maintenance for a criterion pollutant were required to demonstrate that their transportation plans, programs and projects contributed to the attainment of National Ambient Air Quality Standards (NAAQS) and would not cause a new violation or delay attainment of the NAAQS. This process is referred to as Air Quality Conformity. 

  • Connecticut is divided into two non-attainment area for the 8-hour ozone NAAQS and one non-attainment area for fine particulate matter (PM2.5): 
  • New York-Northern New Jersey-Long Island Ozone non-attainment area – Fairfield, New Haven and Middlesex counties; designated as “moderate” non-attainment. 
  • Greater Connecticut Ozone non-attainment area – Hartford, Litchfield, New London, Tolland and Windham counties; designated as “moderate” non-attainment. 
  • New York-New Jersey-Connecticut (NY-NJ-CT) PM2.5 non-attainment area – Fairfield and New Haven counties; designated as attainment and maintenance.

The MPOs covering the NVCOG planning region demonstrate conformity with the Clean Air Act requirements based on air quality emissions assessments of the transportation system based on the implementation of planned and proposed transportation projects. The CTDOT is responsible for conducting the emissions assessments for the MPOs. The conformity test requires the emissions from the future transportation system to be less than the EPA-approved levels. 


Air Quality Conformity 2015 Ozone Emission Results Summary Gtr-CT         
Air Quality Conformity 2015 Ozone Emission Results Summary NY-NJ-CT
Air Quality Conformity 2015 PM2.5 Emission Results Summary GBVMPO
Air Quality Conformity 2015 PM2.5 Emission Results Summary CNVR MPO