	Background

On May 18, 2005, the U.S. Environmental Protection Agency (EPA) promulgated the first national standards for mercury emissions from coal-fired electric power plants. In the United States, coal-fired power plants are the largest emission source, accounting for 42% of total mercury emissions according to EPA. EPA's 2005 regulations, referred to as the Clean Air Mercury Rule (CAMR), establish a cap-and-trade program for power plant mercury that will take effect in 2010. CAMR will have little impact on emissions before 2018, however. At that time, the regulations call for a 69% reduction in emissions as compared to the 1999 level. In setting the limit so far in the future, EPA stated, in part, that mercury control technologies are not commercially available, and will not be generally available until after 2010. Many observers disagree with that conclusion, including a growing number of states. Which States Are Setting Standards

As of February 2007, 18 states have established more stringent emission limits that will take effect sooner than will EPA's, and four other states are developing regulations that would do so. The states with regulations already promulgated (or laws enacted) represent a broad cross-section of states, including Arizona, Colorado, Connecticut, Delaware, Florida, Illinois, Maryland, Massachusetts, Minnesota, Montana, Nevada, New Hampshire, New Jersey, New York, North Carolina, Oregon, Pennsylvania, and Virginia. What the Standards Will Require

		Rates, Dates, Compliance, and Trading

As shown in Appendi x es A and B , the specifics of the state standards vary in stringency, in effective dates, and in numerous other details. First, at least 15 of the state programs will require reductions of 80% to 90% in mercury emissions when fully implemented. Second, the effective dates range from 2007 at the earliest to 2015, with a majority of the programs imposing at least a first phase reduction by 2010. Fourth, unlike the CAMR program, a key feature of which is the trading of emission allowances, the state programs generally prohibit interstate trading of mercury credits; many prohibit in-state trading, as well. These prohibitions address the concern that mercury hot spots might persist if individual plants could avoid installing controls by buying credits. Thus, it can be difficult to compare the stringency of various state requirements.
In March 2005, the U.S. Environmental Protection Agency (EPA) promulgated the first national emission standards for mercury emissions from electric power plants. EPA studies conclude that about 6% of American women of child-bearing age have blood mercury levels sufficient to increase the risk of adverse health effects (especially lower IQs) in children they might bear. Power plants account for 42% of total U.S. mercury emissions, according to EPA. Thus, there has been great interest in the agency's power plant regulations.
The regulations established a cap-and-trade program to address power plant emissions, but the program would have little impact on emissions before 2018. At that time, the regulations call for a 69% reduction in emissions as compared to the 1999 level.
In setting the limit so far in the future, EPA stated, in part, that mercury control technologies were not commercially available, and would not be generally available until after 2010. Many observers disagreed with that conclusion, including a growing number of states. As of February 2007, 18 states (Arizona, Colorado, Connecticut, Delaware, Florida, Illinois, Maryland, Massachusetts, Minnesota, Montana, Nevada, New Hampshire, New Jersey, New York, North Carolina, Oregon, Pennsylvania, and Virginia) have established more stringent emission limits, which take effect sooner than will EPA's, and four other states are developing regulations that would do so.
The state standards vary in stringency, in effective dates, and in numerous other details, but a number of generalizations can be made:
Most of the state programs will require reductions of 80% to 90% in mercury emissions when fully implemented; by comparison, the federal program requires a 22% reduction in its first phase and 69% when fully implemented. The effective dates of the state programs range from 2007 at the earliest to 2015; the federal requirements will not be fully implemented until at least 2025. The state programs generally prohibit interstate trading of mercury credits, and many also prohibit in-state trading. The trading prohibitions address the concern that "hot spots" with high concentrations of mercury might persist if individual plants could avoid installing controls by buying credits.
This report reviews the state standards for mercury emissions from power plants and discusses issues raised by the promulgation of such standards. Among these are whether states can prevent the sale of credits generated by compliance with state regulations in EPA's national credit trading program, and the potential impact of state programs on court challenges to EPA's national regulations.