Wildfire smoke may also include microbes

Residents of the Lewiston-Clarkston Valley and surrounding cities have woken up to a haze of wildfire smoke for the last two weeks registering between “moderate” and “unhealthy” on the U.S. Air Quality Index.

Wildfire smoke is made up of gases and fine particles produced when trees, vegetation and other organic materials burn. The health effects of breathing in it are well-documented, and prolonged exposure is associated with risk of asthma, strokes and respiratory infection.

However, less is known about the microorganisms transported by wildfire smoke.

Leda Kobziar, a fire ecologist at the University of Idaho, is one of the leading figures in the field of pyroaerobiology. Her team examines how microbial life is aerosolized by wildfire smoke, and what the implications are for humans and ecosystems downwind.

“Anything affected by combustion, if it’s small enough and lightweight enough, can be incorporated into the smoke column,” Kobziar said.

A paper published in the Dec. 18 issue of Science, co-authored by Kobziar, brought new concerns about airborne pathogens embedded in smoke’s particulate matter.

“There are different bacteria and fungi aerosolized that can stimulate asthmatic responses or disrupt the respiratory system — even when they’re not living,” she said. “We’re more interested in the living ones, because they could be infectious. They can land and grow in a human airway.”

In 2017, Kobziar and her team collected soil samples from the UI’s Experimental Forest and burned them in a lab to gather air samples. After a week of sitting in a dark room, diverse communities of organisms began to appear, multiplying on the plates. According to the researchers’ 2018 paper published in Ecosphere, many of the microbes were unexpectedly alive.

“The potential for smoke to aerosolize and transport viable microbes is a virtually blank piece of the microbial biogeography puzzle with far‐reaching implications,” they wrote in the paper.

According to Kobziar, between 60 percent to 80 percent of cells in the smoke plumes they’ve studied were found to be alive. Their size determines how long they’ll stay in the column and how high up they can go.

While some can be infectious, she says many of the microbes are beneficial and critical to sustaining life on Earth.

“We’ve found organisms responsible for fixing nitrogen,” Kobziar said. “In the past, it’s just been presumed the most important parts of the smoke are the particulate matter. It wasn’t really established that living organisms make up a significant portion.”

Her latest project, an epidemiological study led by the University of Florida, investigates fungal infections in smoke inundation events throughout the West. While much of the team’s research is done on prescribed burns, they’ve used drones to collect samples from low-intensity wildfires on occasions when it wouldn’t interfere with fire suppression activities.

Kobziar said she’s interested in possibly sampling from one a local wildfire, like the Snake River Complex or Lick Creek fires.

“This is my backyard,” she said. “I really care about the people here, including the immunocompromised who have more severe reactions to smoke and the firefighters who get more of it than anyone else.”

There are still many questions, Kobziar says, and not many definitive answers.

Her team recently submitted a paper with the hopes of publication in the next few months. Two bigger grants, one from the National Science Foundation and another from the W. M. Keck Foundation, will fund new research into the microbes this year that’s focused on human health impacts from smoke.

“We think we could learn a lot about the real world from it,” Kobziar said. “It certainly looks like this summer will provide us with a lot of sampling opportunities, maybe more than we want.”

She hopes to be out in the field as early as next week.

Palermo may be contacted at apalermo@lmtribune.com. Follow her on Twitter @apalermotweets.