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Mercury: Much Ado About Nothing?

How the Clean Air Mercury Rule will affect coal prices.

Fortnightly Magazine - June 2005

In March 2005, Acting Administrator of the Environmental Protection Agency (EPA), Steve Johnson, signed into law the Clean Air Mercury Rule (CAMR), the first regulation to reduce mercury emissions from power plants in the United States. When fully implemented, CAMR will reduce electric utility mercury emissions by almost 70 percent from the 48 tons that were emitted in 1999.

Mercury is a toxic pollutant that is of greatest concern when it accumulates in the food chain. Concentrations of mercury in the air and land are typically low and do not pose any direct threat to human health. However, when airborne mercury deposits on the ground through precipitation, it eventually enters into rivers, lakes, and oceans. Once there, mercury may transform into methylmercury, its most toxic form to humans. Humans are exposed to methylmercury by eating fish from water where mercury is found. Predator fish in particular ( e.g., salmon, shark, tuna, etc.) tend to bioaccumulate the greatest concentrations of methylmercury at levels thousands or even millions times greater than found in the water. Most Americans are exposed to mercury through the consumption of fish. However, roughly 80 percent of the fish consumed in America comes from overseas in waters beyond our control. In regions where fish from local waters are consumed, mercury hotspots likely will become future clean-up targets. 

Exposure to high levels of mercury has been associated with neurological, renal, respiratory, and developmental problems in humans. Health effects can include tremors, loss of sensory or cognitive ability, convulsions, and death. The developing fetus, infants and young children are most susceptible to the ill effects of mercury. 

According to the EPA, U.S. power plants account for about 40 percent of total anthropogenic, or human-caused, mercury emissions in the United States (48 tons out of 120 tons). Mercury emissions from U.S. utilities contribute just 1 percent to the approximately 5,000 tons of annual global mercury emissions from all sources. As a comparison, Chinese power plants release an estimated 495 tons of mercury into the atmosphere per year, over 10 times the amount from U.S. plants. Overall, scientists estimate that up to 30 percent of mercury deposited in the United States originates in China. The large gap in mercury emissions between U.S. and Chinese power plants has led some economists and scientists to question whether reducing Chinese mercury emissions would more cost-effectively reduce mercury deposited in the United States than would reducing U.S. mercury emissions.

The Clean Air Mercury Rule impacts new and existing coal-fired electric generating plants through a market-based cap-and-trade program similar to the EPA’s highly successful Acid Rain Program. The first phase of the program will be implemented in 2010 when mercury emissions are reduced to 38 tons. The second phase goes into action in 2018 with a final mercury emissions cap of 15 tons. The EPA’s 1999 Mercury Information Collection Request (ICR) and other studies provided the data used to analyze mercury emissions