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Transportation Conformity Alert

November 17, 2005

The purpose of this message is to alert Division staff to issues associated with the implementation of transportation conformity under the PM2.5 standard on April 5, 2006. In particular, we want to ensure our partners are aware of approval and authorization issues for projects in PM2.5 nonattainment areas after that date.

As you know, effective April 5, 2005, EPA designated 39 areas (see as nonattainment for the PM2.5 air quality standard. Under Section 176(c)(6) of the Clean Air Act, transportation conformity will apply in those areas on April 5, 2006. This provision of the Clean Air Act and this deadline were not effected by the enactment of SAFETEA-LU.

In PM2.5 nonattainment areas, conformity determinations on metropolitan transportation plans and TIPs must be made by FHWA/FTA by April 5, 2006, or the restrictions of a conformity lapse will apply (see

However, this deadline also affects project authorizations and approvals. After April 5, 2006, project-level conformity determinations must be made prior to final NEPA approval (i.e., ROD, FONSI, or CE) and/or project authorizations for non-exempt projects or project phases. This applies to project authorizations made after April 5, 2006, even if the final NEPA approval was before April 5, 2006.

Project level conformity determinations will require that the project come from a conforming transportation plan/TIP or associated PM2.5 regional emissions analysis. In addition, a PM2.5 hot-spot analysis may be required. However, EPA has yet to finalize PM2.5 hot-spot requirements, and may not do so until March 31, 2006. Therefore, although project-level conformity determinations will be required after April 5, 2006, we may not know the final criteria and requirements for PM2.5 hot-spot analysis until only a few days before. DOT and EPA will be discussing if we can offer further project level guidance prior to the release of the final rule.

State DOTs, MPOs, and project sponsors may therefore wish to closely examine their project schedules in PM2.5 nonattainment areas. Project schedules may warrant adjustment to either advance the scheduled approval or authorization to before April 5, 2006, or to allow additional time to allow for the project-level analysis.

If you think your State may be facing the April 5, 2006 deadline to demonstrate PM2.5 project level conformity or that the deadline may affect specific project delivery, or if you have any questions regarding transportation conformity, please contact Cecilia Ho at 202-366-9862 or, Gary Jensen at 202-366-2048 or, or Emily Tait at 202-366-9482 or

Updated: 1/31/2017
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