Newspaper article The Canadian Press

Fort McMurray Wildfire Will Leave Toxic Legacy: Experts

Newspaper article The Canadian Press

Fort McMurray Wildfire Will Leave Toxic Legacy: Experts

Article excerpt

Wildfire will leave toxic legacy: experts

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EDMONTON - Danger from the Fort McMurray wildfire that has destroyed entire city blocks in the northern Alberta city won't end when the flames stop.

Research from California fires that have burned through homes and communities suggests such blazes leave a threatening legacy of caustic ash and toxic heavy metals.

"There's no doubt, it is hazardous," said Scott Stephens, a fire scientist at the University of California Berkeley.

California has sad experience with wildfires raging through urban areas. Every summer, said Stephens, the state loses homes to marauding flames from the woods.

Wildfires big and bad enough to force their way into communities are generally hot enough to burn off hydrocarbons such as vinyl siding, nylon carpets or household chemicals.

"Fires really do incinerate most of that material," Stephens said. "No doubt that has an impact on air quality, but the vinyls, the tires, the materials that you'd never think would burn ... most of that stuff is gone."

House fires can burn for more than an hour at temperatures reaching 1,500 C, he said.

"You'll look and try and find your dishwasher or your refrigerator. You might find its motor, you might find a few things, but a lot of it has just disappeared."

But the ash left behind poses real threats.

The U.S. Geological Survey found ash left after California's home-destroying wildfires in 2007 and 2008 was far more alkaline than ash from wood fires. Mixed with water, the ash was almost as caustic as oven cleaner.

It was also significantly contaminated with metals, some of them toxic. Arsenic, lead, antimony, copper, zinc and chromium were all found at levels exceeding Environmental Protection Agency guidelines.

Ash particles from urban-wildfire blazes tended to be smaller and more easily inhaled. Both arsenic and hexavalent chromium -- a form of the metal known to cause lung cancer -- were more readily taken up by lung fluids than they were in water. …

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