Governors' Biofuels Coalition

 WASHINGTON — The Environmental Protection Agency unveiled new standards on Wednesday sharply limiting emissions of mercury and other toxic pollutants from the nation’s coal- and oil-burningpower plants.

The new rule, unless blocked by Congress or the courts, will be the first time the federal government has enforced limits on mercury, arsenic, acid gases and other poisonous and carcinogenic chemicals emitted by the burning of fossil fuels.

Lisa P. Jackson, the E.P.A. administrator, said the regulations, which have taken more than 20 years to formulate, would save thousands of lives and return economic and health benefits many times their estimated $9.6 billion annual cost.

“By cutting emissions that are linked to developmental disorders and respiratory illnesses like asthma, these standards represent a major victory for clean air and public health — and especially for the health of our children,” Ms. Jackson said in statement.

President Obama, who in September rejected a proposed E.P.A. rule covering smog-causing emissions as too burdensome to industry, said he fully supported the new rule. He directed the agency to ensure that companies were given sufficient time and flexibility to comply.

He said the new set of regulations, formally known as the Mercury and Air Toxics Standards, “represents a major step forward in my administration’s efforts to protect public health and the environment.”

Although the release of the rule had been delayed several times, the final version looked much like the proposed regulations published in March. White House officials consulted extensively with industry representatives about the impact of the new standards but in the end asked the E.P.A. for only minor changes.

Republican officials and a number of plant operators criticized the rule and are likely to challenge it in court and in Congress. They said it was too expensive and would force the premature closing of scores of power plants, eliminate hundreds of thousands of jobs and threaten the supply of electricity in some parts of the country.

Scott H. Segal, who represents utilities that would be affected by the rule, said the E.P.A. was playing down the costs and double-counting the benefits. “The bottom line,” he said in an analysis of the regulation, is that “this rule is the most expensive air rule that E.P.A. has ever proposed in terms of direct costs.”

He added, “It is certainly the most extensive intervention into the power market and job market that E.P.A. has ever attempted to implement.”

Environmental advocates challenged Mr. Segal’s analysis, and his views are not universally shared in the power industry. Ralph Izzo, the chief executive of the Public Service Enterprise Group, the parent of New Jersey’s largest electric utility, said his company had spent $1.3 billion to bring his plants into compliance with New Jersey’s air quality rules, which are as stringent as the new federal standards. He said other utilities had had more than enough notice to clean up their facilities in advance of the federal rule announced on Wednesday.

Mr. Izzo said that the E.P.A. action was “long overdue,” and that the Clean Air Act, under which the new standards were issued, provided enough flexibility to allow all power generators to come into compliance without a threat to the electric supply.

Mercury is a neurotoxin, harming the nervous systems of fetuses and young children and causing lifelong developmental problems,according to the E.P.A. Other pollutants covered by the new rule, including dioxin, can cause cancer, premature death, heart disease and asthma, the agency said.

Power plants generally have up to four years to comply, although waivers can be granted in individual cases to ensure that the lights stay on. The E.P.A. estimated that utilities would be forced to retire plants that currently provide less than one-half of 1 percent of the nation’s generating capacity.

The rule is the first national one to put limits on emissions of mercury and other toxic gases from power plants, although more than a dozen states have imposed such regulations. The George W. Bush administration proposed a rule covering mercury emissions, but environmental and health groups blocked it in court on the ground that it did not meet the minimum standards of the Clean Air Act.

Senator James M. Inhofe of Oklahoma, the senior Republican on the Environment and Public Works Committee, vowed to block the new regulations.

“Sadly, this rule isn’t about public health,” he said in a statement. “It is a thinly veiled electricity tax that continues the Obama administration’s war on affordable energy and is the latest in an unprecedented barrage of regulations that make up E.P.A.’s job-killing regulatory agenda.”

The E.P.A. said that when the rule was fully in effect, it would prevent 90 percent of the mercury in coal burned in power plants from being emitted into the air and reduce acid gas emissions from power plants by 88 percent.

The rule applies to 1,400 power-generation units at 600 coal- or oil-burning plants. About half the coal boilers lack what the E.P.A. calls “advanced pollution control equipment”; some are more than 50 years old.

The E.P.A. estimated that the rules would eliminate “up to 11,000 premature deaths” per year, along with thousands of heart attacks, asthma attacks and emergency room visits.

The impact on the electric system is difficult to quantify, in part because the administration is moving forward on two other major rules affecting power plants, one for plants east of the Rockies that send pollution across state borders, and another governing discharges of warm water. Plant owners may calculate that it is cheaper to build a new plant burning natural gas than to upgrade an old coal-burner.

Susan F. Tierney, a consultant who was an assistant secretary of energy for policy during the Clinton administration and a utility regulator in Massachusetts, said the cross-state rule and the new mercury rule might push out of business plants that were “on the margin” financially.

Plants with stronger economics may upgrade to control mercury and other hazardous pollutants, she said, because the water rule is still several years in the future.

Ms. Tierney said the mercury rule was the biggest E.P.A. rule on power plants since the mid-1990s, although other changes could be coming. “Under existing rules, it’s really the next big action-forcing regulation,” she said. Eventually, she said, E.P.A. regulation of greenhouse gases could have a broader impact, but that rule is still being written.