Wildfires have taken over from industry as a major source of a group of cancer-causing chemical toxins in the air, Environment Canada says.
The first national review of polycyclic aromatic compounds in over 25 years showed improved air surrounding aluminum and steel plants. Federal researcher Elisabeth Galarneau said however, wildfires and vehicles stepped in, keeping the average concentrations of these substances at levels similar to those in the 1990s.
Polycyclic aromatic compounds are created during the burning of everything from oil to wood to cigarettes. Many are carcinogenic and are considered priority pollutants by the U.S. Environmental Protection Agency.
There are no federal guidelines for these chemicals. Alberta, Quebec and Ontario have made recommendations, but Galarneau said only Ontario’s guidelines are based on effects on human health.
Research has found that climate change contributes to bigger, hotter fires by drying out forests and extending the fire season.
Other increased sources of the chemicals are increased vehicle emissions as well as residential wood-burning. The contributions of those sources vary widely from place to place.
Vehicles account for less than 10% of national emissions, but in Toronto, that figure can be as high as 50% or more.
This is the fourth in a series of recent Canadian air quality research publications. Two more projects are due and a final summary will be released in the coming months.
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