Researchers Say Infectious Microbes Could Be Lurking in Wildfire Smoke

Scientists gather smoke samples during a prescribed burn at the Fire and Smoke Model Evaluation Experiment in Utah’s Fishlake National Forest. (Credit: J. Juchtzer)

(CN) — After a year of near-record wildfires that burned more than 9.5 million acres across the U.S. and turned California’s skies an apocalyptic orange in September, researchers are drawing attention to a little-known but potentially concerning component of wildfire smoke: infectious bacteria and fungi.

It’s already well known that the particulate matter and pollutants in wildfire smoke can cause a variety of health problems, from coughing to difficulty breathing to more serious issues like increased risk of heart attacks and strokes.

But in a paper published Thursday in Science Magazine, researchers from Idaho and California warned of an emerging body of science showing that wildfire smoke can also carry living microbes through the air, making the smoke a “potential infectious agent.”

That possibility, the researchers said, deserves further study, especially as climate change is expected to make wildfires more frequent and more intense in the years ahead.

“People have always assumed that there really isn’t anything significant living in smoke,” Leda Kobziar, a University of Idaho wildland fire expert and co-author on the paper, said in an interview. “This new idea that there is a biology of smoke is really changing the way that people are thinking about things.”

Multiple studies in recent years from Kobziar and her colleagues have shown that bacteria and fungi can be released into wildfire smoke when things like soil and trees are burned. Kobziar said the research has found evidence of smoke carrying at least one type of fungus – the southwestern coccidioides – that is known to cause Valley Fever, a typically mild flu-like disease.

Still, Kobziar said it’s unclear whether microbes carried by smoke could amount to a significant public health concern.

“The folks who work in infectious disease, including my co-author, suggest that what we really need to ask is whether or not this is something that is potentially spreading infectious disease agents,” Kobziar said. “The bottom-line answer is we just don’t know for sure.”

Scientists say the already well-studied health impacts of wildfire smoke are likely to become an even more serious issue with the effects of climate change. In Thursday’s paper, the researchers warned that climate trends also make the question of microbes in wildfire smoke all the more urgent.

“How far and which microbes are transported in smoke under various conditions are critical unknowns, but the relevance of these questions is increasing with longer wildfire seasons and higher severity trends,” they wrote.

Kobziar cautioned that the study was not meant to simply spark concern, but rather to encourage other researchers to get involved in the effort to better understand this emerging field of wildfire science.

“It could be that there are beneficial organisms [in the smoke], there could be things that have broad ecological positive effects as well,” she said. “The bottom line is just that we really don’t know, and that’s what we’re hoping to inspire more people to become interested in finding out.”

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