Two companies, with different products and different locations, both repeatedly foul the air around Pittsburgh. One generates electricity, the other produces coke for steelmaking, and neither one, fortunately, is about to get away with perpetual pollution.

That's because two public agencies, the state Department of Environmental Protection and the Allegheny County Health Department, have been trusty watchdogs for the people they serve.

DEP (along with four other states) has sued Allegheny Energy for suspected violations of the federal Clean Air Act. It has three power plants in Pennsylvania -- Mitchell in Washington County, Hatfield's Ferry in Greene County and Armstrong in Kittanning. With 23 plants in the United States, the company ranks fifth for sulfur dioxide emissions and 10th for nitrogen oxide.

In May the Hatfield's Ferry and Armstrong plants turned up as the top two sulfur dioxide polluters in Pennsylvania in a report called "Dirty Kilowatts" by the Environmental Integrity Project on the nation's 359 largest power plants. Clean-air violations at Hatfield's Ferry are also the reason that Citizens for Pennsylvania's Future filed suit in U.S. District Court in February against the Greensburg-based energy company.

Allegheny Energy said last week it was disappointed in the DEP lawsuit, and its president said the company was trying to improve its pollution controls "as rapidly as our financial condition allows." But it's 2005, and DEP is right to remind the company in court that human lungs won't wait indefinitely.

The other clean-air enforcement case involves Shenango Inc., now practically a serial polluter on Neville Island. The county health department, which had been tolerant of the coke plant's emissions, will announce "significant penalties" this month after it compiles the second-quarter violations.

Shenango has operated under three separate federal consent orders in the last 25 years and been fined more than $2 million. Yet a county health spokesman called the plant's performance since April "abysmal." County inspection reports show the plant complied with combustion stack emissions limits only 40 percent of the time in April, its coke oven push emissions 36 percent of the time and its coke ovens only 13 percent of the time.

The county's role, as protector of the public health, is to remind the plant's owners that, like breathing, clean-air compliance must be a 24/7 activity.

It's hard to believe that in the region where industrial smoke controls were pioneered after World War II, bad air can be Page 1 news in the 21st century. DEP and the county health department want to put an end to such corporate indifference. Too bad they have to do it through lawsuits and stiff fines.