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
- the entire General Conformity Regulations (PDF) (48 pp, 5MB) - November 30, 1993.
- Final revisions to the General Conformity Regulations (PDF) (134 pp, 432 KB) - March 24, 2010
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:
- General Conformity Regulations (PDF) (48 pp, 5MB) - November 30, 1993
- Stakeholders - agencies besides EPA with an interest in General Conformity
- Guidance: Questions and Answers (PDF) (49 pp, 2.1MB) - July 13, 1994
- Guidance: Questions and Answers (PDF) (2 pp, 6KB) - October 19, 1994
- Region IX Memorandum to David Kessler of FAA (PDF) (2 pp, 95 KB) - January 25, 1995
- Guidance for Airports: Questions and Answers (PDF) (31 pp, 60KB) - September 25, 2002
- Airport Emission Reduction Guidance (PDF) (45 pp, 312KB) - September 30, 2004
- Revision to General Conformity Applicability Questions and Answers (PDF) (3 pp, 112 KB) - June 5, 2006
- General and Transportation Conformity Frequently Asked Questions (PDF) (5pp, 51k) - April 6, 2011
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.