Comment submitted by Laurel L. Kroack, Chief, Bureau of Air, Illinois Environmental Protection Agency (Illinois EPA)

The Illinois Environmental Protection Agency (Illinois EPA) appreciates the opportunity to comment on the proposed rule issued in the May 15, 2009 Federal Register (74 FR 23024) concerning the transportation conformity requirements for the revised PM2.5 national ambient air quality standard (NAAQS). The Illinois EPA agrees with the U.S. Environmental Protection Agency’s belief that “a more recent year than 2002 is appropriate for meeting Clean Air Act conformity requirements for 2006 PM2.5 nonattainment areas.” The Illinois EPA supports the use of a more recent year as it would be more environmentally protective, incorporating the benefits of more stringent motor vehicle emissions standards. We also believe that it is logical to link the interim conformity emissions baseline year with the baseline year being used in State Implementation Plan development for the respective standard. For these reasons, the Illinois EPA supports proposed Option 2, which would likely result in a conformity baseline year of 2008 for the 2006 PM2.5 NAAQS. Year 2008 emissions are expected to serve as the base year for SIP planning to meet the 2006 PM2.5 NAAQS, better linking transportation and air quality planning. The use of 2008 motor vehicle emissions levels would also provide a more current estimate of motor vehicle emissions on which to base transportation conformity determinations. As these motor vehicle emissions estimates are expected to be less than earlier years due to the further implementation of more stringent motor vehicle emission standards, the 2008 base year would allow fewer emissions and be more protective of human health. Please contact Mike Rogers at 217/524-4408 with any questions regarding these comments.