EPA Rule Identifies Hazardous Air Pollutant Compounds

The Environmental Protection Agency published a final rule identifying 21 compounds emitted by motor vehicles and fuels as hazardous air pollutants. The rule marks the first time EPA has identified compounds as Mobile Source Air Toxics.

The list developed by EPA includes diesel particulate matter and diesel exhaust organic gases. The rule also describes a technical analysis plan through which the agency intends on better understanding the risks posed by air toxics to public health and welfare.

Many of the emission control programs put in place under the 1990 Clean Air Act Amendments reduce air toxics emissions from a wide variety of mobile sources. These programs include EPA's upcoming off-road diesel fuel and emissions rule, as well as the recently finalized on-road rule for heavy-duty engines and highway diesel fuel sulfur control requirements.

EPA's programs have largely targeted reducing ambient concentrations of criteria pollutants such as nitrogen oxides, volatile organic compounds, carbon monoxide and particulate matter. These programs have reduced and will continue to significantly reduce on-highway emissions of air toxics in the future.

EPA declined to establish additional vehicle-based air toxic controls in its final rule at the present time because its proposed and current programs achieve the greatest degree of MSAT controls that are feasible when cost and other relevant factors are considered. However, due to the potentially serious effects exposure to air toxics may have on human health, the agency will be carefully assessing whether it should establish additional controls, set new toxic emission performance standards and add additional compounds to the MSAT list.

Based upon information acquired by EPA under its technical analysis plan set out in the rule, the agency will conduct a future rulemaking to be completed no later than July 1, 2004. For more information, visit EPA's Mobile Source Air Toxics Web site.

Updated: Feb. 25, 2004