The Clean Air Act was implemented to remedy the damaging effects that bad air quality can have on human health and the environment. Although it is a federal act applied nationally, much of the work and planning is done at the state and local level to tailor air quality requirements to local needs. The Act was most recently revised in 1990, when major changes were enacted.
The Clean Air Act is administered by the U.S. Environmental Protection Agency (EPA), which sets National Ambient Air Quality Standards (NAAQS). These are limits on certain “criteria” air pollutants, including limits on how much of these pollutants can be in the air anywhere in the United States. Geographic areas that are in compliance with standards are called “attainment areas,” while areas that do not meet standards are called “nonattainment” areas. The location of areas designated by U.S. EPA as polluted under the Clean Air Act is documented in the U.S. EPA’s Green Book on Nonattainment Areas for Criteria Pollutants.
In addition to the EPA, the Clean Air Act is administered by state, tribal, and local agencies, which are responsible for developing local solutions to air quality problems. States must develop State Implementation Plans (SIPs) to regulate their state air quality.
In order to show compliance with the NAAQS, projects funded by HUD must demonstrate that they conform to the appropriate SIP.
Does your project include new construction or conversion of land use facilitating the development of public, commercial, or industrial facilities OR five or more dwelling units?
Federal projects must conform to Clean Air Act requirements if they may constitute a significant new source of air pollution. If your project does not involve new construction or conversion of land use as indicated above, it can be assumed that its emissions are below de minimis levels and the project is in compliance with the Act.
If so, is your project’s county or air quality management district in nonattainment or maintenance status for any criteria pollutants?
Refer to the EPA’s Green Book on Nonattainment Areas for Criteria Pollutants to determine the compliance status of the county or air quality management district where you project is located for each criteria pollutant.
If your project’s county or air quality management district is in attainment status for all criteria pollutants, the project is in compliance with the Clean Air Act. Otherwise, determine which criteria pollutants are in nonattainment or maintenance status and proceed to step 3.
If so, do estimated emissions levels for your project exceed de minimis emissions levels for the nonattainment or maintenance level pollutants?
In a nonattainment or maintenance area, a conformity determination is required for each pollutant where the project’s total direct and indirect emissions exceed de minimis levels.You can contact your Air Quality District for help with making this determination and to obtain documentation, or you may make the determination yourself by locating the applicable de minimis levels and estimating the levels of your project.
Refer to EPA’s Conformity determination thresholds at 40 CFR 93.153 to determine the de minimis level for each nonattainment or maintenance level pollutant. Emissions modeling sites, such as caleemod.com, as well as EPA Conformity determination thresholds at 40 CFR 93.153 may assist with determining estimated emissions levels of your project. Again, you may also contact your Air Quality District for assistance. Correspondence from the Air Quality District may serve as documentation for purposes of this question.
If the project’s estimated emissions levels are below de minimis levels for all nonattainment or maintenance pollutants, the project is in compliance with the Clean Air Act and no further action is required. Record all estimated emissions levels as well as all documents used to make your determination in the Environmental Review Record.
If the estimated emissions levels exceed de minimis levels, determine whether the project can be brought into compliance with the SIP through modification or mitigation.
If the project cannot be brought into compliance with the SIP, it cannot proceed as designed.
The environmental review record should contain one of the following: