Mercury Emissions to the Air: Regulatory and Legislative Proposals

Publication Date: May 2004

Publisher: Library of Congress. Congressional Research Service

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On December 15, 2003, the Environmental Protection Agency (EPA) proposed standards for emissions of mercury from coal-fired electric power plants, under the authority of Sections 111 and 112 of the Clean Air Act. (The proposal appeared in the Federal Register January 30, 2004.) In their first phase, the standards could require a 29% reduction in emissions by 2008 or 2010, depending on the regulatory option chosen. A nearly 70% reduction would take effect in 2018, although EPA indicates that flexibility built into the proposed standards could delay the full 70% reduction to as late as 2030.

EPA's analysis of the proposed rule indicates that its benefits would outweigh the compliance costs by a factor of at least 16 to 1, leading many critics of the proposal to ask why the regulations should not be more stringent, or implemented more quickly. The Agency's official position is that technology will not be available to achieve reductions greater than 30% until after 2010. EPA's own Office of Research and Development (ORD) appears to disagree, however. A recent ORD white paper found that reductions of 72% - 98%, depending on coal type, are already being achieved at some plants using current technology. Other issues likely to be raised in the public comment period, which extends until June 29, include the impacts on eastern coal production and the effect of the proposals on mercury "hot spots."

In addition to EPA's regulatory effort, in the current Congress nine bills have been introduced to regulate these emissions. An Administration bill, the "Clear Skies Act," has many points in common with the EPA regulatory proposal. The other bills before Congress are generally more stringent than the Administration's approach.

These regulatory and legislative proposals reflect increasing concern over the potential health effects of mercury emissions. Mercury is a potent neurotoxin that can affect human health at very low concentrations. EPA considers children born to women with umbilical cord blood-mercury concentrations above 5.8 parts per billion to be at increased risk for adverse health effects, such as delayed development, neurological defects, and mental retardation. Recent EPA studies conclude that at least 7.8% (and possibly as many as 15.7%) of American women of child-bearing age have blood mercury levels above this threshold.

U.S. air emissions of mercury come from eight principal sources. Of these, the largest source, and the last major source for which emission standards have been proposed, is coal-fired electric power plants. Coal-fired power plants account for between one-third and one-half of total U.S. mercury emissions.

This report provides background on mercury and reviews regulatory and legislative proposals to reduce emissions of mercury to the air. CRS Report RL32203 and CRS Report RL31908 discuss legal issues raised by EPA's proposed rules and mercury in products and waste, respectively. This report will be updated as warranted.