New York´s plan calls for coal-fired utility power plants to reduce their mercury emissions by 50 percent from current levels by 2010. A 90 percent reduction would be necessary by 2015.

The proposal, announced by Gov. George Pataki, a Republican, would prohibit the trading of emission credits -- a key component of the federal plan.

"Mercury emissions from coal-fired power plants can have severe environmental and public health impacts, and we must take aggressive steps to control these harmful emissions and reduce the presence of this pollutant in our air and water," Pataki said when he announced the proposal May 25.

Mercury is a toxic pollutant that accumulates in the environment, and exposure at high levels can damage the nervous system and kidneys. Pregnant women and children are particularly at risk.

The federal government unveiled a plan to reduce mercury emissions by only 70 percent, and the plan would allow the trading of credits between facilities.

Critics argue the federal plan doesn´t go far enough fast enough and that trading credits could result in so-called mercury hot spots.

"We´re pleased that New York state is moving forward with a state initiative to reduce toxic mercury emissions from New York´s coal-burning power plants," said Katherine Kennedy of the Natural Resources Defense Council. "Gov. Pataki´s and [the Department of Environmental Conservation´s] leadership on this issue is especially important given the inadequate controls on mercury at the federal level."

However, the EPA and many in the utility industry argue that no current technology is proven to reduce mercury emissions by 90 percent, and that a cap-and-trade system is the most efficient and cost-effective means of reducing mercury emissions.

New York officials estimate their plan would add only 86 cents per month to the average residential customer´s electric bill.

However, the Independent Power Producers of New York, a trade association, said it lacks confidence in that estimate and believes the cost could be considerably higher.

"We´re concerned about the impact of the cost to the industry and from a reliability standpoint," association President Gavin Donohue said.

Donohue said the impact could drive up residents´ costs and encourage power companies to take plants out of operation, jeopardizing the reliability of service.