Revision to the Washington State Implementation Plan; Approval of Motor Vehicle Emission Budgets and Determination of Attainment for the 2006 24-Hour Fine Particulate Standard; Tacoma-Pierce County Nonattainment Area

The EPA is approving a request submitted by the Washington Department of Ecology (Ecology) dated November 28, 2012, to establish motor vehicle emission budgets for the Tacoma-Pierce County fine particulate matter (PM<INF>2.5</INF>) nonattainment area to meet transportation conformity requirements. Under the Clean Air Act (CAA), new transportation plans, programs, and projects, such as the construction of new highways, must "conform" to (i.e., be consistent with) the State Implementation Plan (SIP). The CAA requires federal actions in nonattainment and maintenance areas to "conform to" the goals of the SIP. This means that such actions will not cause or contribute to violations of the National Ambient Air Quality Standards (NAAQS), worsen the severity of an existing violation, or delay timely attainment of any NAAQS or any interim milestone. Under the Transportation Conformity Rule, the EPA can approve motor vehicle emission budgets based on the most recent year of clean data if the EPA approves the request in the rulemaking that determines that the area has attained the NAAQS for which the area is designated nonattainment. In September 2012, the EPA finalized an attainment finding for the Tacoma-Pierce County PM<INF>2.5</INF> nonattainment area (hereafter referred to as "Tacoma-Pierce County Area" or "the area"). This finding, also called a clean data determination, was based upon quality-assured, quality-controlled, and certified ambient air monitoring data showing that the area had monitored attainment of the 2006 PM<INF>2.5</INF> NAAQS based on the 2009-2011 data available in the EPA's Air Quality System. This action updates the previous finding of attainment with more recent 2010-2012 data and approves motor vehicle emission budgets under the Transportation Conformity Rule.