DARRYL DYCK/The Canadian Press
“Those big industrial point sources have been reduced to a very small fraction of the total,” she says. “The largest source by far is the natural emissions from forest fires.”The levels are still high enough in many places across the country to exceed health guidelines, the assessment found. “ guideline is exceeded almost everywhere we looked in Canada,” Galarneau said. “The exceedances in some areas are well over an order of magnitude.”
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.
“Everywhere you look, it seems people are coming to the same conclusion. There are other compounds beyond those 16 that make toxicity, and our measurements and models should probably expand to incorporate those.”