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General Conformity

Basic Information

airport control tower

General Conformity covers most aspects of airport activities funded by federal agencies. The Federal Aviation Administration (FAA) and EPA have coordinated to produce guidelines for General Conformity at airports.

In November 1993, EPA promulgated two sets of regulations to implement Section 176(c) of the Clean Air Act. First, on November 24, EPA promulgated the Transportation Conformity Regulations, which apply to highways and mass transit. These regulations establish the criteria and procedures for determining whether transportation plans, programs, and projects funded under title 23 U.S. C. or the Federal Transit Act conform with the State Implementation Plan (SIP) (58 FR 62188). Then, on November 30, EPA promulgated a second set of regulations, known as the General Conformity Regulations, which apply to all other federal actions. These regulations ensured that other federal actions also conformed to the SIPs (58 FR 63214).

The purpose of the General Conformity Rule is to:

  • Ensure that federal activities do not cause or contribute to new violation of National Ambient Air Quality Standards (NAAQS);
  • Ensure that actions do not cause additional or worsen existing violations of  or contribute to new violations the NAAQS; and
  • Ensure that attainment of the NAAQSs is not delayed.

For more information regarding these regulations, you can view and download

You will need Adobe Reader to view some of the files on this page. See EPA's PDF page to learn more.


EPA has developed several guidance documents on General Conformity. Most recently, EPA developed a question and answer document in conjunction with the Federal Aviation Administration (FAA). This document offers further guidance on the implementation of the General Conformity Rule at airports, but also provides helpful guidance that is applicable to other federal activities. Links to the General Conformity Q&A document and other guidance documents and policy statements follow:

The following states have had their conformity rules approved by EPA: Alabama, Alaska, Arizona, California*, Colorado, District of Columbia, Delaware, Illinois, Iowa, Indiana, Kansas, Kentucky, Louisiana, Maine, Maryland, Michigan, Minnesota, Missouri, Montana, Nebraska, New Hampshire, New Mexico, Ohio, Oregon, South Carolina, Texas, Virginia, West Virginia, and Wyoming.

* EPA has accepted the SIP plans for these areas in California: South Coast AQMD, Santa Barbara County APCD, San Joaquin Unified APCD, Yolo-Solano AQMD, Ventura County APCD, San Diego APCD, Sacramento APCD, Placer County APCD, Monterey Bay Unified APCD, Mojave AQMD, Feather River AQMD, Imperial County APCD, Great Basin Unified APCD, El Dorado County APCD, Butte County APCD, and Bay Area AQMD.

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