Fort McMurray homes had normal levels of indoor toxins after wildfire: study

A new study indicates dust from homes in FortMcMurray, Alta., had normal levels of indoor contaminants a year after a devastating forest fire hit the city, suggesting residents did not face an elevated health risk in the aftermath of the blaze.

Arthur Chan, a chemical engineering professor at the University of Toronto, said pollutants in house dust his team analyzed actually contained fewer toxins than homes in many other Canadian cities.

"We don't see any cause for alarm," Chan said. "We found that the levels are below what the guidelines considered as risky."

The results were published last week in the journal Geophysical Research Letters.

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Chan said he and two other researchers spent three weeks going house to house in July 2017, about 14 months after the blaze, sucking up dust from bedrooms and living rooms areas with the highest exposure with commercial grade vacuums. They later analyzed what they collected in a lab.

The team went through more than 60 houses for the study.

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The researchers were driven to perform their work after residents raised safety concerns in wake of the massive wildfire that forced 88,000 people from their homes. Chan said the research was believed to be the first to look for the retention of "fire-derived pollutants" indoors.

"That's partly because these kinds of fires are rare and it's hard to mobilize quickly to go into the community to do the study," Chan said.

The research team was examining the house dust for the levels of polycyclic aromatic hydrocarbons, which are found in high concentrations in burned forests, and heavy metals that are found in high concentrations in ashes from burned buildings.

They found trace elements of the heavy metal arsenic in house dust in neighbourhoods that were heavily damaged by fire compared to non-damaged neighbourhoods, but the levels weren't above Alberta's health guidelines, Chan explained. The researchers found no evidence of polycyclic aromatic hydrocarbons in Fort McMurray house dust.

"We still don't know why, but we think maybe people did a very good job cleaning or maybe from this event there isn't that much of an impact indoors," Chan said. "Whatever it is, it is minimizing the health risk."

He said he hopes his results informs rebuilding and recovery efforts after wildfires.

"We expect this will be an important set of results for the future because there are likely going to be more wildfires because of climate change and difference in land uses," he said.

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Chan and his team are working on several other related studies. They have gone back to Fort McMurray three other times to look at long-term levels of pollutants inside homes as well as seasonal effects.

They are also working with a lung specialist who is conducting a parallel study looking at the residents of the same houses Chan's team has examined.

"The idea is to compare what's around you to what's in you," Chan said.