Programs

Air Quality Regulations and Guidance

The National Environmental Policy Act (NEPA) requires federal agencies, in cooperation with state and local governments, to address the environmental impacts of a proposed federal action or an action that receives federal funds. CDOT must comply with NEPA and the environmental procedures established by the Federal Highway Administration (FHWA), which includes air quality requirements.

Nonattainment and attainment/maintenance areas are subject to requirements under the transportation conformity regulation (40 CFR 93), which ensures that federal funding and approval goes to transportation projects that meet air quality goals.

Both regional and local analyses are needed to demonstrate project level conformity for roadway improvements:

  • Regional conformity is demonstrated by the project being included in a fiscally-constrained, air-quality-conforming plan or program to address long-term and regional air quality impacts that may come from modifying the transportation system as described above.
  • Local (also called hot-spot, project level, or micro-scale) conformity is demonstrated by showing that an individual project will not contribute to any new local violations, increase the frequency or severity of any existing violation, or delay timely attainment of the NAAQS or any required interim emissions reductions or other milestones.

The following CDOT guidance shall be used for projects that have a Scoping Date that is on or after February 14, 2019. Scoping Date is defined in the AQ-PLAG release memorandum. The AQ-PLAG will be used later in 2019 to update the air quality section of Chapter 9 of the August 2017 version of CDOT's NEPA Manual.

FHWA's October 18, 2016, Updated Interim Guidance on MSATs should be used to conduct MSAT analyses.

Additional related guidance

AASHTO

CDOT

EPA

FHWA

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