Approval and Promulgation of Air Quality Implementation Plans; Virginia; Incorporation of On-Board Diagnostic Testing and Other Amendments to the Motor Vehicle Emission Inspection Program for the Northern Virginia Program Area

EPA is approving three State Implementation Plan (SIP) revisions submitted by the Commonwealth of Virginia. These revisions pertain to the Commonwealth's motor vehicle inspection and maintenance (I/M) program for the Northern Virginia area that was previously SIP- approved by EPA. These three SIP revisions incorporate changes made by the Commonwealth to the I/M program since EPA last approved the I/M program as part of the SIP in 2002. The most significant change to the program is the incorporation of on-board diagnostic computer checks of 1996-and-newer model year vehicles as an element of the emission inspection process for the Northern Virginia program area. In addition, Virginia made numerous minor changes to the program, including several changes to test procedures and standards, as well as changes to its roadside testing regimen. The I/M program helps to ensure that highway motor vehicles operate as cleanly as possible, by requiring vehicles to be periodically tested and by identifying vehicles having high emissions due to malfunctioning emission control systems. Such vehicles must then be repaired and retested by their owners, to the standards set by the Commonwealth's program. Vehicle I/M programs address nitrogen oxide and volatile organic compound emissions, both of which are precursors to formation of ground level ozone pollution, as well as the pollutant carbon monoxide. This action is being taken under the Clean Air Act (CAA).