General Conformity

Established under Section 176(c) of the Clean Air Act, the General Conformity Rule, as codified in 40 Code of Federal Regulations Part 51 Subpart W and 40 Code of Federal Regulations Part 93 Subpart B, ensures that the actions taken by federal agencies in nonattainment and maintenance areas do not interfere with a state’s plans to meet National Ambient Air Quality Standards (NAAQS).

The general conformity requirements only apply in nonattainment and maintenance areas. A nonattainment area is an area designated by EPA as not meeting a NAAQS. A maintenance area is an area that was once designated as nonattainment but is currently meeting and maintaining the standard. See information on Georgia’s nonattainment and maintenance areas.

The general conformity rule applies to all federal actions that are taken in designated nonattainment or maintenance areas. However, there are exceptions:

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

* minimum threshold for which a conformity determination must be performed (listed for each criteria pollutant)

Under the general conformity rule, those responsible for the federally funded project must work with the state agency responsible for a nonattainment or maintenance area to ensure that federal actions conform to the air quality plans established in the applicable state implementation plan. In Georgia, federal actions that are typically affected by the general conformity rule are airport and military base expansions. 40 CFR Part 51, Subpart W, as amended April 5, 2010, has been incorporated and adopted into the Georgia Rules for Air Quality Control, Chapter 391-3-1-.14 General Conformity.

In an area with a State Implementation Plan (SIP), conformity can be demonstrated in one of the following 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 implementation of emissions reductions to offset the action’s emissions in the same or nearby area
  • Through mitigation to reduce the emission increase