Wildfire Smoke Can Carry Dangerous Microbes Thousands of Miles, Scientists Warn

Smoke from the Woolsey Fire in California in 2018.

Smoke from the Woolsey Fire in California in 2018. Copernicus Sentinel

Scientists are warning that wildfire smoke can carry microbes that cause infectious diseases, adding another public health concern to the worsening severity of wildfires across the globe. The analysis, published in the journal Science, said there while the pulmonary and cardiovascular consequences of wildfire smoke inhalation have been well researched, the risk of potential infection from airborne microbes has not.

The fungus coccidioides, for example, becomes airborne when soils are disturbed by fire. When inhaled, it can cause Valley fever, an infection with flu-like symptoms that in more severe cases can progress to pneumonia or meningitis. Risk of inhalation of these infectious microbes is highest closest to the fire — the Centers for Disease Control and Prevention actually lists coccidioidomycosis as a professional risk for overland firefighters, Wired reports. But wildfire smoke has also been shown to carry airborne particles of fungal and bacterial cells, which hitch a ride on water vapor or charred carbon, over thousands of miles.

One recent study found an increase in cases of invasive mold infection, aspergillosis, and coccidioidomycosis at hospitals within 200 miles of major wildfires in California.

“We don’t know how far and which microbes are carried in smoke,” George Thompson, an associate professor of Clinical Medicine at UC Davis and co-author of the new analysis, said in a statement. “Some microbes in the soil appear to be tolerant of, and even thrive under, high temperatures following wildfires.”

Thompson and his co-author, Leda Kobziar, a fire scientist at the University of Idaho, said a multidisciplinary research collaboration is needed to better understand the relationship between microbes, wildfires, and public health — particularly as severe wildfires become seasonal norms in parts of the world such as the United States and Australia.

“With longer wildfire seasons and higher severity trends, there is an urgency to work together in studying the behavior of the microbes carried by the smoke and their impact on human health,” Thompson said.