Skip to content U.S. Department of Transportation/Federal Highway AdministrationU.S. Department of Transportation/Federal Highway Administration
Office of Planning, Environment, & Realty (HEP)

Transportation Conformity Highlights

June 2005

EPA Corrects Two Errors in PM2.5 Precursors Rule. On June 1, EPA issued a notice correcting two minor errors that were in the May 6, 2005 rule on PM2.5 precursors. The notice does not make any changes to the final rule but only clarifies explanatory text and corrects reference citations. This rule can be found at:

Conformity in Noncontiguous PM2.5 Nonattainment Areas. EPA's Office of Transportation and Air Quality (OTAQ) recently issued guidance clarifying how conformity applies in noncontiguous PM2.5 nonattainment areas. Noncontiguous PM2.5 nonattainment areas are areas that contain "satellite portions" that are not contiguous with the main portion of the nonattainment area. These satellite areas are designated as part of the overall nonattainment area because they have a point source that contributes, via transport, to the air quality problems of the main geographic portion of the PM2.5 nonattainment area. OTAQ indicates that the satellite portions best fit the definition of a donut area for transportation conformity purposes. Transportation conformity guidance for donut areas can be found in EPA's "Companion Guidance for the July 1, 2004, Final Transportation Conformity Rule: Conformity Implementation in Multi-jurisdictional Nonattainment and Maintenance Areas for Existing and New Air Quality Standards". A PDF copy of the multi-jurisdictional guidance can be download at

EPA Announces Fourteen Areas are Ahead of Schedule to Reduce Ground-Level Ozone. Fourteen Early Action Compact (EAC) areas have met a recent milestone and EPA proposes to defer Clean Air Act requirements pertaining to ground level ozone for these areas until December 31, 2006. EPA will accept comments on this proposal for 30 days after publication in the Federal Register. For more information, see:

Maintenance Plan Guidance Document for Certain 8-Hour Ozone Areas Under Section 110(a) of the CAA. On May 20, 2005 EPA issued guidance on developing maintenance plans for areas that are designated unclassifiable/attainment for the 8-hour ozone standard and that were either nonattainment or maintenance for the 1-hour standard. Areas required to develop 110(a) (1) maintenance plans are not considered "maintenance areas" for the purposes of conformity because conformity for the 8-hour ozone standard does not apply in areas that are designated unclassifiable/attainment for that standard. EPA is expected to post this guidance on its website soon. Please contact the Transportation Conformity Team if you want to receive a copy of this guidance.

NTI Course: Introduction to Transportation Conformity. Courses will be offered in Chicago, IL on June 15-17, Baton Rouge, LA on August 22-24, and Burbank, CA on October 26-28. Additional courses are being scheduled through February 2006. For information and to register go to:

FHWA Resource Center Training Activities.FHWA's Resource Center Air Quality Technical Services Team is available to offer air quality-related training opportunities and information can be found at:

If you have any suggestions for future monthly conformity highlights, please email:

FHWA Resource Center Air Quality Team Contacts:

Updated: 1/31/2017
HEP Home Planning Environment Real Estate