Study links wildfire smoke to worsening air quality in western U.S.

Nathan Howes
·3 min read
Study links wildfire smoke to worsening air quality in western U.S.
Study links wildfire smoke to worsening air quality in western U.S.
Study links wildfire smoke to worsening air quality in western U.S.

Wildfires are nothing out of the ordinary for the western United States, but a new study has found a connection between the smoke they generate and the number of extremely poor air quality events.

The new research comes from the University of Utah, tying the worsening trend of a decline in air quality incidents in the U.S. West to wildfire activity, with a spike in the tendency of smoke impacting air quality persisting into September.

The study's findings were recently published in Environmental Research Letters.

wildfire-smoke-trends/Kai Wilmot
wildfire-smoke-trends/Kai Wilmot

Changes in daily average particulate matter in the month of August from 2000-2019. Points outlined in black indicate statistical significance. Photo: Kai Wilmot.

“In a big picture sense, we can expect it to get worse,” Kai Wilmot, lead author of the study and doctoral student in the Department of Atmospheric Sciences, said in a news release.

“We’re going to see more fire area burned in the western U.S. between now and in 2050. If we extrapolate our trends forward, it seems to indicate that a lot of urban centres are going to have trouble in meeting air quality standards in as little time as 15 years.”


Numerous residents living in the U.S. West have become accustomed to the smoky skies during the summer in recent years, especially in 2020. The wildfire season in 2020 was a record-breaking and disastrous one. It took 31 lives, destroyed more than 10,000 structures and burned a total over 4 million acres of land (1.6 million hectares).

Wilmot, a native from the Pacific Northwest, has seen firsthand the smoke. As part of the study, he and his colleagues examined data from extreme air quality events in the West from 2000-2019 to see if they corresponded with summer wildfires.

While researchers did find consistency in trends in air quality that matched up with wildfire activity, they found different spatial patterns in August than in September.

Bobcat Fire in California/September 2020
Bobcat Fire in California/September 2020

The Bobcat Fire rages in California in September 2020. Photo: Nikolay Maslov/Unsplash.

They used air measurements of PM2.5 -- or the amount of particulate matter in the air with diametres under 2.5 micron -- from the Environmental Protection Agency (EPA) and the IMPROVE monitoring network, along with measurements of area burned by fire and the PM2.5 emitted from those fires, to come to the conclusions.


In the years that were examined for the study, researchers took note that the mean air quality was becoming progressively worse in the Pacific Northwest in an average August when there was prevalent smoke from wildfires.

“That’s pretty dramatic,” Wilmot said. “That extreme events are strong enough to pull the mean up, so that we’re seeing an overall increase in particulate matter during August across much of the Pacific Northwest and portions of California. The Pacific Northwest seems like it’s just really getting the brunt of it.”

Wilmot attributes that to wildfires occurring in August in the Pacific Northwest including in northern California and British Columbia. However, the mountainous areas in the region, sits in the "middle," he said.

Wildfires/Getty Images
Wildfires/Getty Images

Photo: Getty Images.

By September, the wildfire activity eases in British Columbia and then progresses to the Rocky Mountains. Along with the fires, the smoke shifts, too. Researchers noticed materializing trends of where the wildfire smoke is with drops in September air quality in Wyoming and Montana.

“We see the PM2.5 trends start to pick up a bit more in the Rockies and they become more statistically significant, a little bit stronger and more spatially coherent,” Wilmot says.

In Utah, air quality tendencies approach "statistical significance," with the university study outlining impact from wildfires, but evidence suggests it's less vigorous there than in the Pacific Northwest and California.

The study noted that researchers involved in different studies have indicated that the future will bring more fire areas burned in the western U.S., accompanied by an elevation in wildfire smoke exposure in the West and its impacts on human health.

Thumbnail courtesy of Getty Images.