Approval and Promulgation of Air Quality Implementation Plans; Pennsylvania; Revised MOBILE6-Based Motor Vehicle Emission Budget for the Pennsylvania Portion of the Philadelphia-Wilmington-Trenton Ozone Nonattainment Area

EPA is taking direct final action to approve a revision to the Pennsylvania State Implementation Plan (SIP). Specifically, EPA is acting to approve a revised 2005 highway motor vehicle emission inventory for the Pennsylvania portion of the Philadelphia-Wilmington- Trenton (the Philadelphia area) 1-hour ozone attainment plan. This revised highway vehicle emissions inventory also serves as the 2005 motor vehicle emissions budget for purposes of determining transportation conformity under the Clean Air Act. The revised mobile emissions budget was developed using MOBILE6--the most recent available version of the EPA-developed MOBILE highway motor vehicle emission factor model. Revision of the mobile budget was a requirement of EPA's prior approval of the Commonwealth's 1-hour ozone National Ambient Air Quality Standard (NAAQS) attainment demonstration for the Philadelphia severe ozone nonattainment area. The intended effect of this direct final approval action is to approve a SIP revision that will assist Pennsylvania in attaining and conforming to attainment of the 1-hour ozone NAAQS standard in the Philadelphia area. This action is being taken by EPA in accordance with the requirements of the Clean Air Act.