WASHINGTON – A Bush administration decision to let some coal-burning power plants escape costly pollution controls is intended to help keep electric bills in check, but environmentalists say it will increase smog and contribute to asthma and other respiratory ailments.

The proposal sent to President Bush by the Environmental Protection Agency on Thursday calls for relaxing clean air rules to make it easier for utilities, oil refineries and industrial plants to upgrade and expand.

“These reforms are about making the Clean Air Act work effectively,” EPA Administrator Christie Whitman said.

“We are not rolling back the Clean Air Act,” she added, anticipating the barrage of criticism from Democrats and environmentalists that soon followed her announcement.

“Once again, White House political considerations have trumped our nation’s commitment to promoting clean air and improving the public health of millions,” said House Democratic Leader Dick Gephardt of Missouri.

Maine Sens. Olympia J. Snowe and Susan Collins expressed strong opposition to the EPA proposal.

“Maine suffers disproportionately from the impact of transported pollutants from the Midwest and Southwest,” Snowe said in a fax statement, “and I am concerned that the relaxed emissions proposal under the New Source Review process … will only make the problem worse.”

“We should fight to keep our state’s lakes, coast and forests clean,” she said.

Collins, calling on the administration to eliminate the grand-fathering provision of the Clean Air Act, said that “all power plants should meet the same standards.”

“I strongly urge the administration to reconsider its decision to go forward with its proposed changes,” she said in a press release.

EPA Assistant Administrator Jeff Holmstead said the EPA had no data indicating what effect the proposal would have on the level of air pollution in the United States.

The “New Source Review” part of the Clean Air Act is intended to force power plants to install pollution-reducing devices when they make physical changes – such as expansion – that could significantly increase pollution.

Scott Segal, an attorney for power companies, said utilities could save as much as $70 billion – passing much of it on to consumers through lower bills – by not having to install expensive equipment to reduce emissions.

“NSR is a highly regressive tax because the poor pay so much of their paycheck on electricity costs,” he said.

Environmentalists said the savings from relaxing New Source Review requirements are not worth what they said would be an increased incidence of asthma and other lung ailments.

“These same plants emit pollution that triggers between 107,000 and 170,000 asthma attacks every year, most of which occur in children,” said Angela Ledford, director of a coalition of environmental groups called Clear the Air. “If these plants were forced to install pollution controls and comply with the law, between 80,000 and 120,000 of these attacks could be avoided.”

Vickie Patton, an attorney with Environmental Defense in Boulder, Colo., said the decision will enable thousands of power plants, oil refineries and industrial facilities across the country to increase their pollution, often without notifying the public.

EPA is likely to face a court challenge from environmentalists and state and local air regulators, whose trade associations issued a statement calling the decision “irresponsible.”

State attorneys general from several states in the Northeast also have said they would challenge in federal court any substantial weakening of the program.

“Our ongoing lawsuits against these polluters will continue with undiminished determination despite this proposal – or because of it – perhaps even providing a forum to challenge it,” said Connecticut Attorney General Richard Blumenthal.

Vice President Dick Cheney’s task force asked the EPA last year to re-examine New Source Review and report back in 90 days, but the issue became embroiled in lengthy internal debate over how far the agency should go in easing requirements for the utilities.

White House press secretary Ari Fleischer said the intent is to give industries greater flexibility as they perform repairs and maintenance on plants and expand electricity production without having to install a whole range of other emissions controls.

The current regulations, he said, often discourage companies from investing in new pollution reduction projects.

“Many of these people who are affected have chosen to leave in place old equipment, which pollutes more, rather than replace it and modernize it, which pollutes less,” Fleischer said.

Whitman said the proposal will not diminish her agency’s efforts to pursue cases begun during the Clinton administration against several utilities over pollution from 51 power plants.

“We’re not going to relent,” she said.

The EPA and the Justice Department have threatened heavy fines on utilities unless they spend tens of billions of dollars to more strictly control emissions of acid rain-causing sulfur dioxide, smog-causing nitrogen oxides and mercury, a toxic chemical that contaminates waterways.