area sources in an integrated urban air toxics strategy. The 1999 strategy document identifies 32 high-priority HAPs (plus diesel exhaust) and lists 29 area-source categories that have been or will be targeted for regulation, including 13 new categories for which standards are to be issued by 2004. For area sources, the agency has the discretion to issue either MACT standards or less stringent generally available control technology (GACT) standards. EPA is now proceeding with implementing these regulations.
To date, the efforts to control area sources have been relatively scattered and have slipped far behind mandated implementation schedules. Recent efforts, such as the integrated air toxics strategy, have begun to bring some strategic vision to the control of such sources. However, in the absence of a high-quality inventory of such sources, it is nearly impossible to quantify their emission contributions and to set priorities. Yet, those few analyses that have been done (for example, by EPA in the HAPs inventory) suggest that area-source emissions are significant and will be even more important after the imposition of MACT has reduced emissions from the major industrial sources. A renewed focus on improving area-source inventories and controlling key sources at an accelerated pace will be important in crafting effective strategies to reduce emissions and exposure to many important pollutants.
CAA programs have achieved substantial reductions of pollutants from existing stationary sources, for example, SO2 (through the Acid Rain Program), VOCs (for example, through RACT), and HAPs (through MACT). The Ozone Transport Commission, and the upcoming NOx SIP call trading program have the potential to achieve substantial reductions in NOx emissions.
NSR and PSD requirements have encouraged the continuous development and application of cleaner technologies and emission controls for major new stationary sources and have resulted in reduced emissions from those sources.
The development of emission cap-and-trade programs that use market forces to limit the cost of pollution control has provided the AQM system with a mechanism that is capable of achieving substantial emission reductions at reduced costs.