It fouls their air and covers their homes and cars with a black film so often that the power company sometimes offers free car washes. They say the pollution makes them sick, and now they're sick of the state Department of Environmental Protection and the U.S. Environmental Protection Agency doing nothing to stop it.

Two environmental groups, on behalf of members in Masontown and southwestern Pennsylvania, filed notice yesterday that they will sue Allegheny Energy for what they term "massive air pollution" that violates federal and state law on an average of six days out of every seven.

"It feels like I'm living with a monster," said O'Rourke, whose home is about a mile east of the power plant. She believes the pollution has caused increased incidence of asthma, cancer and premature death, including that of her husband, who died from a rare cancer at age 57.

"We have nice homes and children down here, but we can't take care of them when Allegheny Energy is doing what it's doing to us and the government says it's OK."

Charles McPhedran, senior attorney for Citizens for Pennsylvania's Future, said the Hatfield's Ferry plant violated its smoke and soot control limits on more than 1,635 days from the beginning of 1999 through the end of 2003. According to records obtained through a Freedom of Information Act request filed with the DEP, there are often multiple violations on a single day.

"This plant has an appalling record of pollution," McPhedran said. "The plant's own records show that month after month it spews soot in violation of standards meant to protect the health of its neighbors."

Janice Lantz, an Allegheny Energy spokeswoman, declined comment, saying the company is reviewing the recently received notice.

"There are a lot of different ways to slice and dice these things," Lantz said about the thousands of alleged violations. "Until we review, we won't have any comment."

After the filing of a formal notice of intent to sue, required under state and federal environmental laws, the power company and state and federal agencies have 60 days to develop a plan to correct the violations before a lawsuit can be filed. The other group that plans to join Citizens for Pennsylvania's future is Environmental Integrity Project.

Maximum penalty for each alleged air pollution violation is $27,500 a day.

"We expect the final judgment to involve a penalty component," McPhedran said. "But more important is the compliance issue. They need to reduce the emissions of fine particles to the levels that meet the permit."

Betsy Mallison, a DEP spokeswoman, said Allegheny Energy has been fined nearly $20,000 for air quality violations since 2000, and the department is "reviewing 2004 data to determine if additional action or penalties are necessary."

She said the state has been a leader in enforcing air pollution limits and joined three other states in May in filing notices of intent to sue Allegheny Energy for emissions violations at five coal- burning power plants in West Virginia after the federal government abandoned investigations of those plants.

"At Hatfield's Ferry we have acted independently to initiate our own investigation into opacity violations, and have been in negotiations with Allegheny Energy," Mallison said.

The Hatfield's Ferry plant has a generating capacity of 1,710 megawatts and is the second largest of the 23 power-generating facilities -- a dozen of them coal-fired -- owned by Allegheny Energy Supply. The company provides power to 690,000 customers in Pennsylvania.