CHARLESTON, W.Va. - The latest "blue haze" to descend on the Kanawha Valley was more widespread and not as easily traced back to American Electric Power's John Amos Power Plant, state investigators said Tuesday.

Department of Environmental Protection investigators did on-the-ground and aerial inspections after reports that the blue haze had returned early Tuesday afternoon.

John Benedict, director of the DEP Division of Air Quality, said it was not as clear as in previous incidents that the haze came from the Amos plant, located across the Kanawha River from Poca.

"It was really hazy everywhere," Benedict said.

"It was a lot hazier downwind from the John Amos plant," Benedict said. "But it wasn't as distinct."

DEP began investigating after hearing reports of the blue haze, and just before Metro 911 issued a statement noting that it had received several complaints about the problem starting at about 1:15 p.m.

It is at least the fourth blue haze incident since late January that DEP has investigated.

Shortly after lunch on Jan. 25, a blue haze started to appear in the air across the Kanawha Valley. Residents called emergency officials to complain about a strange odor, and asked if there was a chemical leak. County officials surveyed the area, but there were no reports of any unusual release or operating problems.

Federal and state officials later concluded the incident was likely caused by emissions from the Amos plant.

In a May report, DEP officials concluded that weather conditions transformed sulfuric acid emissions from the plant into an aerosol, creating the blue mist.

Department of Environmental Protection investigators did on-the-ground and aerial inspections after reports that the blue haze had returned early Tuesday afternoon.

John Benedict, director of the DEP Division of Air Quality, said it was not as clear as in previous incidents that the haze came from the Amos plant, located across the Kanawha River from Poca.

"It was really hazy everywhere," Benedict said.

"It was a lot hazier downwind from the John Amos plant," Benedict said. "But it wasn't as distinct."

DEP began investigating after hearing reports of the blue haze, and just before Metro 911 issued a statement noting that it had received several complaints about the problem starting at about 1:15 p.m.

It is at least the fourth blue haze incident since late January that DEP has investigated.

Shortly after lunch on Jan. 25, a blue haze started to appear in the air across the Kanawha Valley. Residents called emergency officials to complain about a strange odor, and asked if there was a chemical leak. County officials surveyed the area, but there were no reports of any unusual release or operating problems.

Federal and state officials later concluded the incident was likely caused by emissions from the Amos plant.

In a May report, DEP officials concluded that weather conditions transformed sulfuric acid emissions from the plant into an aerosol, creating the blue mist.

Burning coal with sulfur in it produces sulfur dioxide. Inside plant stacks, some of that sulfur dioxide is converted to sulfur trioxide. When the sulfur trioxide exits the stack, it reacts with moisture in the air to form sulfuric acid.

Over the past few years, AEP has added pollution control equipment aimed at reducing nitrogen oxide emissions, but that equipment can also enhance the creation of sulfur trioxide, increasing the potential for sulfuric acid emissions.

After the January incident, AEP notified the U.S. Environmental Protection Agency that Amos was releasing up to 32,500 pounds of sulfuric acid per day, nearly eight times the company's previous estimate.

The DEP cited AEP for the January incident, but the company is appealing.

On Tuesday, AEP spokeswoman Jeri Matheney said the company had "people in the field to try to find first-hand the conditions residents have reported."

Matheney said AEP has "confirmed that operating conditions at the plant are normal today."

Benedict said AEP officials had told him that Amos was exceeding its visible emissions limits earlier in the day at the largest of the plant's three generating units. The company cut back on generation at that unit to fix the problem, Benedict said.

Reach Ken Ward Jr. at kw...@wvgazette.com or 348-1702.

Read a WVDEP report on blue haze: www.wvdep.org/Docs/15050_BlueHaze-May2008.pdf