Emissions trading is a market-based approach used to control pollution by providing economic incentives for achieving reductions in the emissions of pollutants. Virginia has a number of emissions trading programs, which are mandated by federal law and modified by Virginia law in some respects. Virginia's emissions trading rules are located in 9VAC5 Chapter 140.

The NO_X Budget Trading Program (Part I) was the original means by which the board addressed the transport of ozone-generating pollutants--nitrogen oxides (NO_X) and sulfur dioxide (SO₂)-- across state lines as required by EPA's NO_X SIP Call rule.

The NO_X SIP Call was superseded by EPA's Clean Air Interstate Rule (CAIR). Virginia implemented CAIR through Part II (NO_X Annual Trading Program), Part III (NO_X Ozone Season Trading Program), and Part IV (SO₂ Annual Trading Program). Specific information about CAIR allocations and forms is available here.

EPA's trading rules continue to evolve. Please check EPA's Clean Air Markets program for current information about the federal program, or contact Beth Major for information about Virginia's program.