Air Quality

Our mission is to improve air quality by ensuring that all CDOT projects and operations comply with federal and state air quality laws and regulations, and by promoting strategies that reduce emissions of motor vehicle pollutants. CDOT evaluates air quality impacts of its transportation projects under 40 CFR Part 93 – Determining Conformity of Federal Actions to State or Federal Implementation Plans (Conformity Regulation) to ensure that the project will not cause or contribute to a violation of the National Ambient Air Quality Standards (NAAQS). CDOT evaluates mobile source air toxics and greenhouse gas/climate change emissions for projects that are not Categorically Exempt under the National Environmental Policy Act (NEPA).

Conformity regulations apply only to nonattainment and attainment/maintenance areas. This map shows Colorado’s nonattainment area for ozone (O3) and the attainment/maintenance areas for particulate matter of 10 micrograms in size or smaller (PM10) and carbon monoxide (CO). Go to Colorado's nonattainment SIPs and maintenance plans to see the plans for these areas that are currently not achieving the NAAQS or have not met the standards in the past.

NAA maint area map

Colorado: The Official State Web Portal