Clean Air Act

The Clean Air Act of 1970 (42 USC 85) was enacted to protect air quality in the nation through a number of means – among them, by providing technical and financial assistance to the states for the development and execution of pollution prevention programs. The law authorized the Environmental Protection Agency (EPA) to develop National Ambient Air Quality Standards (NAAQS) and regulate air emissions from area, stationary, and mobile sources. EPA regulations 40 CFR 50-51 contain the NAAQS and the procedures for implementation. U.S. law codified at 23 USC 109 (J) (“Highways”) requires that the Federal Highway Administration (FHWA) develop guidelines for the implementation of NAAQS for pollutants. Vermont has a state law 10 VSA 23 (Air Pollution Control) that authorizes the state to issue permits to pollutant producers and to set thresholds for those pollutants. The state law has no direct involvement with the planning or permitting of transportation projects.

When It Is Required

Conformance with state or federal implementation plans is required for FHWA and FTA projects (40 CFR 93.102) proposed in non-attainment or maintenance areas for pollutants, and for “regionally significant” non-federal projects. Vermont is currently in attainment for all pollutants, so the requirements in 40 CFR 93.102 do not apply unless a proposed project is “regionally significant”. Regionally significant projects (defined in 40 CFR 93.101) serve regional transportation needs, such as principal arterial highways. Certain types of projects are exempt from all conformity requirements – these are listed in 40 CFR 93.126. Other types of projects are exempt from regional emissions analysis only, but still require microscale “hotspot” analysis for carbon monoxide. These are listed in 40 CFR 93.127. VTrans and ANR previously followed an MOA that limited projects that require conformity analysis to those that created an increase of 10,000 vehicles per day, but this MOA is no longer in effect.

A summary of air quality conformity requirements for transportation projects in Vermont has been created for this manual.

Permit or Approval Process

Compliance with the Clean Air Act is required under NEPA for federal projects. There is no permit or application to demonstrate compliance with the Clean Air Act. The Clean Air Act regulates both regional (mesoscale) impacts and local (microscale) impacts. As described above, because Vermont is in attainment for all pollutants, regional (mesoscale) impact analysis is only required for large regionally significant projects. Local (microscale) “hotspot” analysis is required for certain projects (listed in 40 CFR 93.123) that are anticipated to result in higher volumes of traffic. Conformity determinations, when required, follow the procedures outlined in models approved by the EPA.

Related Regulations

Regulatory programs with overlapping jurisdiction with the Clean Air Act include, but are not necessarily limited to, the following:

VT Act 250 (10 VSA 151) – Criterion 1 of the Act requires that a proposed project not result in “undue air pollution”.

For More Information

EPA Region 1

Air Pollution Control Division

5 Post Office Square – Suite 100

Boston, MA 02109-3912

(617) 918-1111

Vermont State Implementation Plan (SIP)

USEPA Air Quality and Transportation