A federal appeals court sided with Maine and 13 other states Friday and stopped the Environmental Protection Agency from going forward with new regulations opponents say would lead to more air pollution from the nation’s power plants and factories.

The new rules would have allowed older power plants, refineries and factories to modernize without having to install expensive pollution controls.

The U.S. Court of Appeals in Washington ruled the EPA’s changes violated the language of the federal Clean Air Act, and that any such change can be authorized only by Congress. Fourteen states and a number of cities, including New York, San Francisco, and Washington, D.C., sued to block the change in October 2003.

Maine Attorney General Steven Rowe called the decision a clear victory for public health and a resounding defeat for the Bush administration, which he accused of demonstrating a “total disregard” for the intent of the Clean Air Act.

“We weren’t surprised because this was so egregious,” Rowe said by telephone Friday afternoon. “The rule promulgated by the EPA created what I would call a gaping hole in the Clean Air Act.”

Peter Lehner, the top environmental lawyer for New York Attorney General Eliott Spitzer, said the decision will apply to about 800 power plants and up to 17,000 industrial factories nationwide and will help reduce pollution emissions blamed for as many as 30,000 U.S. deaths annually.

The court “is upholding the words and purpose of the Clean Air Act as well as EPA’s historical interpretation of the act,” Lehner said.

In her decision, Judge Judith Rogers noted the EPA’s proposed changes stood in contrast to its past practices following the federal law.

The rule would have broadened EPA’s interpretation of “routine maintenance” for older plants. Under the Clean Air Act, operators who do anything more than routine maintenance are required to add more pollution-cutting devices. Under the proposed change, industrial facilities could have avoided paying for expensive emissions-cutting devices if they spent less than 20 percent of the plant’s value, Lehner said.

When it proposed the changes, the EPA said the rule would make it easier to upgrade utilities, refineries and other industrial plants to improve efficiency without being too costly. The EPA said it believed the rule would not lead to more emissions and would preserve public health protections.

The rule had been blocked from going into effect since December 2003 when the same court issued a stay.

“We are disappointed that the court did not find in favor of the United States,” said EPA spokesman John Millett. “We are reviewing and analyzing the opinion and cannot comment further at this time.”

Rowe said that the EPA’s changes would have had a powerful effect on Maine because 85 percent of the pollution that falls from Maine skies comes from out-of-state sources.

But industry groups said the decision would do little to help air quality.

BDN reporter Kevin Miller contributed to this report.