EPA has published a proposed rule that would establish procedures so the agency will not be required to change transportation conformity rules every time national ambient air quality standards (NAAQS) are revised. 75 Fed. Reg., 49,435 (8/13/10). The proposal would revise the rules governing the required emissions analysis used to demonstrate conformity at 40 C.F.R. § 93.109. It would restructure existing requirements for regional conformity tests and project-level conformity tests. It also would change the time frame used to analyze the projected air quality impact of a proposed project so that transportation planners could use data from a year within five years of the conformity determination.

The proposal would also clarify that certain nonattainment areas that have monitoring data showing they are now in attainment with a particular air quality standard can choose to complete a regional conformity analysis using the most recent year of data demonstrating compliance, rather than an interim test listed in 40 C.F.R. § 93.119. EPA will accept comments on the proposed rule through September 13, 2010.