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National Emission Standards for Hazardous Air Pollutants

Fact Sheet

September 2005


The Environmental Protection Agency (EPA) is taking action to remove mercury, lead and other hazardous substances from the environment by reducing air pollutants from hazardous waste combustors. EPA's National Emission Standards for Hazardous Air Pollutants achieve significant long-term ecological and human health benefits without imposing significant regulatory burdens on hazardous waste combustors.


EPA is issuing national emission standards for hazardous air pollutants (HAPs) from hazardous waste combustors (HWCs). The standards implement section 112(d) of the Clean Air Act by requiring hazardous waste combustors to meet HAP emission standards reflecting the application of the maximum achievable control technology (MACT).

The combustors affected by this rule detoxify or recover energy from hazardous waste and include incinerators, cement kilns, lightweight aggregate kilns, boilers and process heaters, and hydrochloric acid production furnaces. EPA estimates that 145 facilities operate 265 devices that burn hazardous waste.

These technology-based standards reduce emissions of hazardous pollutants, including lead, mercury, arsenic, dioxin and furans, and hydrogen chloride and chlorine gas. In addition, emissions of particulate matter are also reduced.

Better control of air pollutants is expected to result in fewer cases of chronic bronchitis, reduced hospitalizations for severe respiratory conditions and cardiovascular problems in adults and children, and fewer cancer cases. Populations residing near hazardous waste combustors may benefit the most from implementation of these standards.


EPA promulgated MACT standards for most HWCs on September 30, 1999. These emission standards created a technology based national cap for hazardous air pollutant emission from the combustion of hazardous waste in these devices.

A number of parties, representing both industrial and environmental communities, requested judicial review of this rule, and challenged its emission standards and several implementation provisions. On July 24, 2001, the United States Court of Appeals for the District of Columbia Circuit vacated the emission standards; however, it allowed EPA to promulgate interim standards that have been in place since February 13, 2002.

EPA proposed new standards on April 20, 2004. Today's standards result from the above judiciary and regulatory actions.

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