Fog and smoke looms over the Lawrence Berkeley National Laboratory in Berkeley, California, on September 9.
Fog and smoke looms over the Lawrence Berkeley National Laboratory in Berkeley, California, on September 9. Paul Chinn/The San Francisco Chronicle/Getty Images

Amid rapidly spreading fires across California and other western parts of the United States, several medical professionals are warning unhealthy air quality from wildfire smoke can make people more susceptible to Covid-19 and worsen existing infections.

“Multiple studies have shown a correlation between higher levels of pollution in the air and greater spread and severity of Covid-19 cases,” said Dr. Brad Spellberg, chief medical officer of the Los Angeles County-USC Medical Center. “Some studies have also shown that exposure of lung tissue to pollution may increase susceptibility to viral infections.”

Higher amounts of air pollution and smoke particles in the air could also predispose people to being more susceptible to acquiring and having more severe Covid-19 disease, Spellberg said, citing several studies conducted in the US, China and Italy.

Dr. Rekha Murthy, an infectious disease specialist and vice president of medical affairs at Cedars-Sinai Hospital in Los Angeles, said smoke from wildfires can irritate the lungs and can cause inflammation that can affect the immune system. That inflammation can make people more likely to experience lung infections, including from viruses like the one that causes Covid-19.

“Whenever the lining of the lung or the airways become inflamed or damaged, it increases the potential for inhaled viral particles to take hold in the lungs and cause infection,” Murthy said.

CNN Medical Analyst and ER physician Dr. Leana Wen also agreed air pollution increases the likelihood of respiratory illnesses — and those illnesses can make vulnerable populations experience more severe effects from Covid-19. Wen said there are also legitimate short-term concerns that the smoke-filled air will likely drive more coronavirus-positive people indoors, which could also potentially lead to a rise in the spread of the virus.

“There is a catch-22 because we know being outdoors versus indoors reduces the rate of transmission by 18- to 19-fold, but now people are being told you have to go indoors because you don’t want to breathe in the air that could cause other respiratory issues,” Wen said. “But you don’t want to be indoors with other individuals and have a higher rate of contracting Covid-19 … so, it’s really a catch-22.”

To prevent the possible spread of Covid-19 during the unprecedented overlapping of an intense fire season during a pandemic, Wen recommends that all individuals who are remaining indoors due to poor air quality should also stay away from anyone who is not in their immediate household.

Murthy, of Cedars-Sinai Hospital, also recommends the best way to protect yourself and others against Covid-19 during the wildfire season is to reduce any possible exposure to smoke by seeking clean air spaces and limiting outdoor exercise.

“Physical distancing may be more challenging in the setting of the wildfires where people are not able to disperse and spend time outside as easily,” Murthy said. “It’s even more important now to remind everyone to not drop their guard and to maintain physical distancing, wear masks and practice hand hygiene.”