Wildfire smoke exposure contributed to increase in COVID-19 cases, scientists say

Wildfire smoke exposure contributed to increase in COVID-19 cases, scientists say
Smoke from Western wildfires blanketed downtown Reno, Nev. on Sept. 11, 2020. Image: Trevor Bexon / This Is Reno

RENO–Persistent wildfire smoke in northern Nevada contributed to an increase in COVID-19 cases in late summer of 2020 according to a team of Reno-based researchers. They published their findings this week in the Journal of Exposure Science and Environmental Epidemiology.

Scientists from the Center for Genomic Medicine at the Desert Research Institute (DRI), Washoe County Health District and Renown Health analyzed the relationship between the presence of fine particulate matter in Reno skies (wildfire smoke is PM2.5) and the COVID-19 test positivity rate during the same period.

From Aug. 16 to Oct. 10, 2020, they found that lingering wildfire smoke in the region’s air was responsible for a 17.7% increase in the number of COVID-19 cases. Reno experienced 43 days of elevated PM2.5 during that timeframe—the most days of any metropolitan area in the region.

“We had a unique situation here in Reno last year where we were exposed to wildfire smoke more often than many other areas, including the Bay Area,” said Gai Elhanan, co-lead author of the study and associate research scientist of computer science at DRI. “We are located in an intermountain valley that restricts the dispersion of pollutants and possibly increases the magnitude of exposure, which makes it even more important for us to understand smoke impacts on human health.” 

Luke Montrose, an assistant professor of community and environmental health at Boise State University, discussed the potential toxicity of wildfire smoke in a recent essay for The Conversation. He said PM2.5 is used to make health recommendations because “it defines the cutoff for particles that can travel deep into the lungs and cause the most damage.”

Elhanan said the research is valuable for public health officials who can use the information to plan ahead to help people avoid smoke during wildfire events which may contribute to COVID-19 cases.

Daniel Kiser, co-lead author of the study and assistant research scientist of data science at DRI, said the information is valuable for northern Nevada health officials now.

“This is important to be aware of as we are already confronting heavy wildfire smoke from the Beckwourth Complex fire and with COVID-19 cases again rising in Nevada and other parts of the Western U.S.,” he said.

The full text of the study, “SARS-CoV-2 test positivity rate in Reno, Nevada: association with PM2.5 during the 2020 wildfire smoke events in the western United States,” is available from the Journal of Exposure Science and Environmental Epidemiology: https://www.nature.com/articles/s41370-021-00366-w