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General Conformity

Frequent Questions

Answers to the following questions can be found by scrolling down or by clicking on the question of interest. If you need further information, please use the contact information provided.

What is the General Conformity Rule?

Why did EPA revise the regulations?

Which actions are subject to the General Conformity Rule?

Which Federal actions are exempt from general conformity?

What is a State Implementation Plan (SIP)?

How can an action be shown to "conform"?

Which emissions are excluded from a conformity determination?

What are de minimis emission levels?

What are nonattainment and maintenance areas?

Where can I learn more about the designations process?

Where can I find guidance regarding the General Conformity Regulations?

Whom can I call to get more information?


What is the General Conformity Rule?

The General Conformity Rule ensures that Federal actions comply with the national ambient air quality standards. In order to meet this Clean Air Act requirement, a Federal agency must demonstrate that every action that it undertakes, approves, permits or supports will conform to the appropriate state implementation plan (SIP).

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Why did EPA revise the regulations?

The U.S. Environmental Protection Agency (EPA) first issued the General Conformity Regulations in 1993. Since that time, several Federal agencies have shared suggestions with EPA regarding ways to improve the General Conformity Regulations. Based on these suggestions and input from states and the public EPA issued revised the General Conformity Regulations in an April 5, 2010 Federal Register notice.

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Which actions are subject to the General Conformity Rule?

Currently, the General Conformity Rule applies to all Federal actions that are taken in designated nonattainment or maintenance areas. However, there are three exceptions:

  • Actions covered by the transportation conformity rule;
  • Actions with associated emissions below specified de minimis levels; and
  • Other actions which are either exempt or presumed to conform.

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Which Federal actions are exempt from general conformity?

Federal Actions that are exempt from the General Conformity Regulations include:

  • Actions covered by transportation conformity,
  • Actions with emissions clearly at or below de minimis levels,
  • Actions listed as exempt in the rule, or
  • Actions covered by a Presumed-to-Conform approved list.

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What is a State Implementation Plan (SIP)?

A state implementation plan is developed in order to improve air quality in designated nonattainment and maintenance areas. Through this plan, States propose their strategy for reducing criteria air pollutant emissions. Plans often incorporate different strategies, such as the use of a permit system to ensure that power plants, factories and other pollution sources meet State clean-up goals.

Working with the EPA, States and cities also implement programs to further reduce emissions of ozone precursors from sources such as cars, fuels, industrial facilities, power plants, and consumer/commercial products.

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How can an action be shown to "conform"?

In an area without a State Implementation Plan (SIP), a federal action can be shown to "conform" by demonstrating there will be no increase in emission in the nonattainment or maintenance area from the Federal action that could cause new violations of the standards and/or no increase in the frequency or severity of previous violations.

In an area with a SIP, conformity can be demonstrated in one of four ways:

  • By showing that the emission increases caused by an action are included in the SIP,
  • By demonstrating that the State agrees to include the emission increases in the SIP,
  • Through offsetting the action’s emissions in the same or nearby area,
  • Through mitigation to reduce the emission increase, or
  • Through an air quality modeling demonstration in some circumstances.

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Which emissions are excluded from a conformity determination?

Emissions excluded from a conformity determination include those subject to New Source Review; those covered by CERCLA or other environmental laws; actions not reasonably foreseeable; and those for which the responsible Agency has no ability to exercise continuing program responsibility.

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What are de minimis emission levels?

Under the existing regulations, de minimis emission levels are listed for each criteria pollutant. Annual emission rates per calendar year are used. You may want to view a listing of de minimis emission levels for each criteria pollutant.

In creating the de minimis emission levels, EPA sought to limit the need to conduct conformity determinations for actions with minimal emission increases. When the total direct and indirect emissions from the project/actions are below the de minimis levels, the project/action would not be subject to a conformity determination.

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What are nonattainment and maintenance areas?

Nonattainment means that an area does not meet the National Ambient Air Quality Standards.

The Clean Air Act identifies six common air pollutants that are found all over the United States. These pollutants can injure health, harm the environment and cause property damage. EPA calls these pollutants criteria air pollutants because the agency has developed science-based guidelines as the basis for setting permissible levels. Ozone is a criteria pollutant. There are National Ambient Air Quality Standards (NAAQS) for each of the criteria pollutants. These standards apply to the concentration of a pollutant in outdoor air. If the air quality in a geographic area meets or does better than the national standard, it is called an attainment area; areas that don't meet the national standard are called nonattainment areas.

In order to improve air quality, states must draft a plan known as a State Implementation Plan (SIP) to improve the air quality in nonattainment areas. The plan outlines the measures that the state will take to improve air quality. Once a nonattainment area meets the standards and additional redesignation requirements in the CAA [Section 107(d)(3)(E)], EPA will designate the area as a "maintenance area."

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Where can I learn more about the designations process?

For more information regarding the designations process, visit EPA's designations web sites. There, you can learn more about the new national ambient air quality standards.

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Where can I find guidance regarding the current General Conformity Regulations?

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

At present, there are three available guidance documents concerning the current General Conformity Regulations:

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Whom can I call to get more information?

For more information on General Conformity, please visit the Contact Us page. To learn more about how General Conformity affects your area, contact your local or State air quality office or regional EPA office.

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