Approval and Promulgation of Air Quality Implementation Plans; Pennsylvania; Approval of the Base Year Emissions Inventory for the Liberty-Clairton Nonattainment Area for the 2006 24-Hour Fine Particulate Matter Standard and Approval of Transportation Conformity Insignificance Findings for the 1997 Annual and 2006 24-Hour Fine Particulate Matter Standards for the Liberty-Clairton Nonattainment Area

The Environmental Protection Agency (EPA) proposes to approve the State Implementation Plan (SIP) revision submitted by the Commonwealth of Pennsylvania for the purpose of meeting the statutory emissions inventory requirements for the Liberty-Clairton nonattainment area (hereafter ``the Liberty-Clairton Area'' or ``the Area'') with respect the 2006 24-hour fine particulate matter (PM2.5) National Ambient Air Quality Standard (NAAQS or standard). The SIP revision consists of the 2007 base year emissions inventory for the Liberty-Clairton Area for the 2006 24-hour PM2.5 NAAQS. EPA is also proposing to approve a SIP revision consisting of Pennsylvania's determinations for both the 1997 annual and 2006 24-hour PM2.5 standards that onroad emissions of PM2.5 and nitrogen oxides (NOX) are insignificant contributors to PM2.5 concentrations in the Liberty-Clairton Area for transportation conformity purposes. In the Final Rules section of this Federal Register, EPA is approving Pennsylvania's SIP submittal as a direct final rule without prior proposal because the Agency views this as a noncontroversial submittal and anticipates no adverse comments. The publication of this document starts a 30-day public comment period on the adequacy of the submitted motor vehicle emission inventories. This comment period is concurrent with the comment period on this direct final rulemaking action. Any comments on the motor vehicle emission inventories should be submitted to the docket for this rulemaking. A detailed rationale for the approval is set forth in the direct final rule. Additionally, a more detailed description of the state submittal and EPA's evaluation is included in the Technical Support Documents (TSDs) prepared in support of this rulemaking action. A copy of the TSDs are available, upon request, from the EPA Regional Office listed in the ADDRESSES section of this document or is also available electronically within the Docket for this rulemaking action. If no adverse comments are received in response to this action, no further activity is contemplated. If EPA receives adverse comments, the direct final rule will be withdrawn and all public comments received will be addressed in a subsequent final rule based on this proposed rule. EPA will not institute a second comment period. Any parties interested in commenting on this action should do so at this time.