Mapping Mercury; September 2005; Scientific American Magazine; by Rebecca Renner; 2 Page(s)

In issuing the Clean Air Mercury Rule this past March, the Bush administration hoped to ease health concerns about mercury from coal-fired power plants. The White House enacted a "cap and trade" approach to reduce emissions of the element nationwide by about 20 percent in five years and 70 percent by 2018. In formulating its rule, the administration noted that power plants emit only 48 tons of the metal every year--just a small fraction of the total amount of mercury in the atmosphere. Mandating further emission cuts, it argued, would not solve the problem of human exposure to the neurotoxin.

Eleven states and four public health groups are challenging this approach, arguing that cap-and-trade does not address areas particularly vulnerable to mercury pollution. Not so, says the Environmental Protection Agency. When the cap-and-trade proposals were announced, the EPA's head of air regulations, Jeffrey Holmstead, said, "We don't think there will be any hot spots." The hot-spot standoff arises from big gaps in mercury science, according to environmental researchers, and the lack of comprehensive data on mercury deposition means that a consensus about emissions control will not likely emerge soon.