Frequent Questions about General Conformity

The following websites may be helpful in understanding the Questions and Answers listed below:

Answers to the following questions can be found by scrolling down to the question of interest. If you need further information, please contact [email protected].

What are the 40 CFR part 93 subpart B General Conformity regulations?
Which general federal activities are subject to General Conformity?
What is an applicable implementation plan?
What does conformity to an applicable implementation plan mean?
Which nonattainment and maintenance areas are subject to General Conformity?
Where to find information about air quality designations for nonattainment areas and redesignations to attainment for maintenance areas?
Which emissions are not included in the General Conformity applicability analysis of the annual total of direct and indirect emissions (i.e., net emissions)?
What are annual de minimis emissions threshold rates?
How can activities be shown to conform?
Where to find guidance regarding the General Conformity regulations?
Person to contact for more information?

1. What are the 40 CFR part 93 subpart B General Conformity Regulations?

Clean Air Act (CAA) Table of Contents (by CAA Title and section, and by 42 U.S.C. section," is the federal "conformity" rule, which requires federal agencies to ensure that emissions caused by activities they propose will not interfere with a State or Tribe's ability to attain and maintain the NAAQS Table specifically when the federal assistance required is to fund, permit or license, or approve activities that are subject to the conformity requirements.

This is accomplished by requiring federal agencies to design and plan their activities to be consistent with (i.e., conform to) the purpose of a State, Tribal, or Federal implementation plan to prevent and control air pollution. Such plans, referred to as State, Tribal, or Federal implementation plans (SIPs, TIPs, or FIPs), must be approved by EPA before they can be "applicable" under General Conformity and applied within EPA-designated nonattainment areas and redesignated attainment areas (i.e., maintenance areas), over which the States and Tribes have authority and jurisdiction.

The EPA implements CAA § 176(c) by promulgating and periodically updating criteria and procedures federal agencies must follow for determining and ensuring conformity for 2 categories of federal activities—

Transportation-related activities. As required under CAA § 176(c)(4)(B), EPA implements criteria and procedures for determining conformity to federal transportation plans, programs, and projects through the Transportation Conformity regulations at 40 CFR part 93 subpart A .
Non-transportation-related (general) activities. As required under CAA § 176(c)(4)(A), EPA implements criteria and procedures for determining conformity to general federal activities through the General Conformity regulations at 40 CFR part 93 subpart B.

2. Which federal activities are subject to General Conformity?

General Conformity applies only to a federal agency's proposed general federal activities, meaning activities not related to transportation plans, programs, or projects as defined under 40 CFR 93.102 "Applicability." Federal activities subject to General Conformity:

Require assistance from a federal agency to obtain funding, a permit or license, or approval;
Would cause emissions of one or more criteria or precursor pollutants to originate within one or more areas designated nonattainment or redesignated attainment (i.e., maintenance areas); and
Would cause emissions of pollutants for which such areas are designated nonattainment or redesigned attainment.

3. What is an applicable implementation plan?

A State, Tribal or Federal implementation plan (i.e., a SIP, TIP, or FIP) is developed in order to attain or maintain the NAAQS within nonattainment and maintenance areas. See Basic Information about Air Quality SIPs. Through the implementation plan, States and Tribes enforce their measures and procedures for preventing and controlling emissions of criteria or precursor emissions within nonattainment or maintenance areas.

4. What does conformity to an applicable implementation plan mean?

Conformity under CAA § 176(c)(1)(A) and (1)(B) to an applicable implementation plan means:

(A) Conformity to an implementation plan's purpose of eliminating or reducing the severity and number of violations of the National Ambient Air Quality Standards (NAAQS) caused by federal activities, achieving expeditious attainment of such standards, maintaining the standards; and

(B) Ensuring that emissions caused by such activities will not—

(i) cause or contribute to any new violation of a NAAQS implemented within nonattainment or maintenance areas;

(ii) increase the frequency or severity of any existing violation of NAAQS implemented within nonattainment or maintenance areas; or

(iii) delay timely attainment of a NAAQS, delay any required interim emission reductions, or other milestones within nonattainment or maintenance areas.

5. Which nonattainment and maintenance areas are subject to General Conformity?

There is a 1-year delay (i.e., grace period) during which General Conformity does not apply to newly designated nonattainment areas under CAA § 176(c)(6). A maintenance area operating under a maintenance plan developed and approved under CAA 175A Maintenance Plans. is subject to General Conformity for a period of 20 years from the effective date the area was redesignated attainment. This timeframe could be extended in a SIP revision.

6. Where to find information about air quality designations for nonattainment areas and redesignations to attainment for maintenance areas?

For more information visit EPA's Green Book for Criteria Pollutants or 40 CFR Part 81 Subpart C -- Section 107 Attainment Status Designations.

7. Which emissions are not included in the General Conformity applicability analysis of the annual total of direct and indirect emissions (i.e., net emissions)?

A federal agency can exclude emissions from the annual total of direct and indirect (net) emissions when the emissions are:

Caused by activities defined by EPA in subpart B as exempt;
Caused by activities presumed to conform (PTC) as listed by EPA in subpart B, or contained in the agency's own list of presumed to conform (PTC) activities published in the Federal Register, or listed in the State or Tribal General Conformity SIP revision;
Subject to CAA 182(f) for emissions of nitrogen oxides (NOx) within an ozone transport region;
Accounted for by Early Emissions Reduction Credits (EERCs) that the federal agency established in the applicable implementation plan according to General Conformity § 93.165. Subject to Transportation Conformity under40 CFR part 93 subpart A § 102 Exempted from environmental regulation under the provisions of the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) and applicable regulations issued under CERCLA; or
Emissions caused by stationary sources subject to control under the Nonattainment New Source (NNSR) Review or Prevention of Significant Deterioration (PSD) program requirements.

8. What are annual de minimis emissions threshold rates?

A federal agency is not required to conduct and prepare a formal General Conformity Determination for those activities with annual emissions increases that are less than the applicable annual de minimis emissions rates. This limits the need for a more rigorous analysis of emissions sources to only those activities that equal or exceed the applicable annual de minimis emissions rates, which would also require the federal agency to meet the requirements of General Conformity §§ 93.155 and 93.156 for reporting and public participation.

9. How can activities be shown to conform?

Activities conform if the federal agency can demonstrate or document that the annual net increase in emissions caused by the activities will not interfere with the State or Tribe's ability to timely attain or maintain the NAAQS. A federal agency can show its activities conform under CAA § 176(c)(1)(A) and (1)(B) by applying one or more, or a combination of the available criteria provided under General Conformity § 93.155 and in accordance with the procedures under General Conformity § 93.156, including:

Demonstrating or documenting the emissions from an activity do not equal or exceed (i.e., emissions are below) the relevant annual de minimis threshold rates at General Conformity § 93.153(b)(1) and (b)(2) for the affected nonattainment or maintenance areas;
Confirming the activities' annual net emissions increases, together with emissions of the same pollutants from other sources already existing within the nonattainment or maintenance areas, do not exceed the SIP budget for such emissions;
Confirming the implementation plan includes a facility-wide emissions budget prepared according to General Conformity § 93.161;
Confirming the annual net increases in emissions from the activities are specifically accounted for in the applicable implementation plan, for instance, in an attainment or maintenance demonstration budget;
Documenting that an agreement exists between the State or Tribal air agency, and the appropriate government officials, to prepare an implementation plan or a revision to an implementation plan to include the annual net emissions increases in the emissions budget for the affected nonattainment or maintenance area;
Obtaining offsets or developing mitigation strategies according to the procedures under General Conformity §§ 93.160, 93.163, 93.164, and 93.165, where any agreements between the State or Tribe, and the federal agency, are enforceable at State and federal levels;
Apply the emissions to air quality modeling according to Appendix W to 40 CFR part 51, Guideline on Air Quality Models, to show the emissions will meet the requirements under CAA § 176(c)(1)(A) and (1)(B); or
Redesign the activity so that emissions can be reduced to below de minimis, for example, by lengthening the construction phase or requiring the use of tiered equipment powered by diesel fuel under 40 CFR part 1039, appendix I Tiered Engine Standards.

10. Where to find guidance regarding the current General Conformity regulations?

Refer to the webpage— Guidance on the General Conformity Regulations.

11. Person to contact for more information?

For more information on General Conformity, please select the "Contact Us" link below. To learn more about how General Conformity affects your area, contact your State or Tribal air quality office or regional EPA office.