New research: Exposure to wildfire smoke linked to higher Covid-19 risk

The research team examined whether smoke from 2020 wildfires in the western US was associated with an increase in SARS-CoV-2 infections in Reno, Nevada.

Firefighters monitor the Sugar Fire, part of the Beckwourth Complex Fire, as it burns at Frenchman Lake in Plumas National Forest, California, on Thursday, July 8, 2021. (AP Photo/Noah Berger, File)

Wildfire smoke may greatly increase susceptibility to SARS-CoV-2, , according to new research from the US institutions Center for Genomic Medicine at the Desert Research Institute (DRI), Washoe County Health District (WCHD), and Renown Health (Renown).

In a study published in the Journal of Exposure Science and Environmental Epidemiology, the research team examined whether smoke from 2020 wildfires in the western US was associated with an increase in SARS-CoV-2 infections in Reno, Nevada.

The team used models to analyse the relationship between PM2.5 from wildfire smoke and SARS-CoV-2 test positivity rate data from Renown Health. According to their results, PM2.5 from wildfire smoke was responsible for a 17.7% increase in the number of Covid-19 cases that occurred during a period of prolonged smoke that took place between August 16 and October 10, 2020.

Reno, located in Washoe County (population 450,000) of northern Nevada, was exposed to higher concentrations of PM2.5 for longer periods of time in 2020 than other nearby metropolitan areas, including San Francisco. Reno experienced 43 days of elevated PM2.5 during the study period, as opposed to 26 days in the San Francisco Bay Area.

The DRI quoted Gai Elhanan, co-lead author of the study , as saying: “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. 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.”

The new research builds upon past studies in San Francisco and Orange County by controlling for additional variables such as general prevalence of the virus, air temperature, and the number of tests done, in a location that was heavily impacted by wildfire smoke.