Wildfire smoke evolves as it drifts from wilderness to city

Key insights

- Decades of fire-suppression policies have left forests rife with fuel to burn; either through wildfires or prescribed burns, our future will likely be smokier than our recent past.

- By the time a smoke plume reaches a distant city, its contents have aged and chemically changed.

- Researchers are working to determine how the composition of aged plumes differs from their fresh counterparts in an effort to understand climate and health risks of our fiery future.

For a few days this summer, millions of people living far from the edge of the wilderness were reminded of the combustive power of wildfires when smoke from uncontrolled infernos burning through the forests of Ontario billowed across the border into the US. Unfortunately, it’s likely that such intermittent hazy days are here to stay.

“We’re in a fire deficit,” explains Tyler McIntosh, a PhD student who studies wildfires with the Cooperative Institute for Research in Environmental Sciences at the University of Colorado Boulder. “We’ve had a lot less fire on the landscape than we theoretically should have over recent history.”