ALBUQUERQUE -- New Mexico has the highest concentration of airborne mercury (Hg) in the country. So incoming Attorney General Gary King has joined other states in opposing a possible solution.

King and the other law enforcement officials in 17 states and city of Baltimore have joined forces to oppose an Environmental Protection Agency (EPA) decision last May. The move would establish a cap-and-trade system to reduce Hg emissions from power plants rather than force them to reduce emissions by legislative fiat.

King said the cap-and-trade proposal "would negate the benefits we've seen with the reduction in pollutants from the previous power plant emissions negotiation." In their joint filing against the EPA, the states say the cap-and-trade proposal "allows power plants to avoid the expense of installing stringent pollution controls to reduce mercury emissions."

A cap-and-trade system sets a ceiling on individual emissions of certain pollutants and then allows the polluters to buy and sell credits on the open market allowing them to emit more. The states claim creating such a system for mercury emissions will encourage the creation of pollution "hot-spots."

Yet EPA figures indicate that the cap-and-trade system has been a significant success in reducing emissions of two major acid-rain pollutants over the past few decades.

Since being introduced for sulfur dioxide (SO2) in 1980, the cap-and-trade system is on track to reduce SO2 emissions 50 percent by 2010. Cap-and-trade for nitrous oxides (NOX), introduced in 1990, projects to reduce NOX emissions 27 percent by 2010.