Approval and Promulgation of Air Quality Implementation Plans; Commonwealth of 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) is taking direct final action to approve two revisions to the Commonwealth of Pennsylvania (Pennsylvania) State Implementation Plan (SIP). The first revision consists of the 2007 base year emissions inventory 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 second revision consists of insignificance findings for the mobile source contribution of PM2.5 and nitrogen oxides (NOX) emissions for the Liberty-Clairton Area for both the 1997 annual and 2006 24-hour PM2.5 standards. EPA is approving the 2007 base year emissions inventory for the Liberty- Clairton Area for the 2006 24-hour PM2.5 NAAQS. Furthermore, EPA is finding the motor vehicle emission inventories adequate for transportation conformity purposes and is approving the insignificance findings for the mobile source contribution of PM2.5 and NOX emissions for the Liberty-Clairton Area for both the 1997 annual and 2006 24-hour PM2.5 standards. EPA is approving these revisions in accordance with the requirements of the Clean Air Act (CAA).