An explosion and asphalt fire at a Wisconsin oil refinery on Thursday sent huge plumes of smoke into the air that pollution experts said almost certainly contains large amounts of toxins, posing a serious health risk to those living downwind.
Asphalt is a petroleum product that when burned emits chemicals in gaseous form and small particles that can linger long after the smoke dissipates, said Wilma Subra, a chemist with the Louisiana Environmental Action Network who has examined past refinery accidents.
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At least 11 people were hurt in the explosion, one seriously.
The gases include so-called volatile organic compounds, or VOCs, which can cause symptoms ranging from dizziness, breathing problems and nausea to liver damage and cancer, depending on the level and length of exposure, according to the U.S. Environmental Protection Agency.
Also present in asphalt smoke are microscopic particles of chemicals that stick together as visible smoke.
The blast at the oil refinery happened at about 10 a.m. Five people were taken to hospitals in Duluth, Minnesota, Superior Fire Chief Steve Panger told The Associated Press. He doesn’t know the extent of their injuries. Others were walking wounded. There were no known fatalities.
A contractor who was inside the building told WDIO television that the explosion sounded like “a sonic boom” and that it happened when crews were working on shutting the plant down for repairs.
Panger said the fire was out by 11:20 a.m. He said a small tank exploded, and the product was either crude oil or asphalt.
Those particles carry cancer-causing benzene and other contaminants that can lodge deep in the lungs when inhaled. From there, they can pass directly into a person’s bloodstream, said Neil Carman, a former refinery inspector for the Texas Commission on Environmental Quality, now with the Sierra Club.
“Anybody breathing that stuff should be very concerned about what’s getting into deep tissue, into the bloodstream,” Carman said. “When you see that kind of smoke, it means you’re getting a lot of unburned hydrocarbons. … Those particles are loaded with carcinogens.”
Burning asphalt at the Husky Energy refinery in Superior, Wisconsin, has prompted the evacuation of much of the town of about 27,000. Local officials say the evacuations are a precaution as a plume of noxious black smoke drifts southward from the plant.
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The duration and extent of the toxic hazard depends on a variety of factors, such as wind direction and speed, proximity to the refinery and weather events that can trap pollution close to the ground, said Elena Craft, senior health scientist for the Environmental Defence Fund.
Owned by Alberta-based Husky Energy, Wisconsin’s only refinery produces gasoline, asphalt and other products. Authorities in Superior say the explosion at the Husky Energy oil refinery happened at about 10 a.m. Thursday.
No damage estimate was available. The Superior Fire Department sent all three engine companies to the explosion, and nearby Duluth sent over a command vehicle.
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Calgary-Alberta-based Husky Energy refinery bought the refinery from Indianapolis-based Calumet Specialty Products Partners last year for over $490 million. It’s Wisconsin’s only refinery, and produces gasoline, asphalt and other products.
The refinery, which dates back to the early 1950s, has a processing capacity of around 50,000 barrels per day and a storage capacity of 3.6 million barrels of crude and products. It processes both heavy crude from the Canadian tar sands in Alberta and lighter North Dakota Bakken crude.