Experts warn wildfire smoke could worsen COVID-19

Wildfires that have left parts of California and other Western states with some of the worst air quality in the world are posing a major threat to people with asthma and other underlying health conditions who are already at greater risk of serious COVID-19 complications.

Exposure to wildfire smoke can weaken immune systems and cause respiratory illnesses, and experts worry that combining those effects with the coronavirus could lead to more severe cases, even death.

As the pandemic continues to take its toll, having killed nearly 200,000 people in the U.S., the western part of the country is facing dual crises that could have a compounding effect. 

“At the levels of air pollution we’re seeing in the Northwest now, it’s a matter of concern for everyone,” said Dr. David Hill, a voluntary medical spokesperson for the American Lung Association.

“So, certainly by itself, we’d be concerned. But with COVID circulating, having worse air quality might make it more likely for them to get infected and have worse disease with COVID-19,” he added.

Wildfires have been burning in Western states for weeks, and at least 34 people have died, according to The Associated Press.

When wildfires burn they release pollutants that can worsen air quality, including one known as particulate matter, which inflames the lungs and has also been linked to heart issues. The elderly and people with underlying health conditions like asthma and lung disease are at greatest risk for serious illness from both COVID-19 and poor air quality caused by wildfires.

On Thursday, the city of Portland, Ore., registered “hazardous” levels of a small type of particulate matter known as fine particulate matter, or PM2.5. Other cities, like Seattle, Salem, Ore., and Fresno, Calif., showed unhealthy or very unhealthy levels of the pollutant on Thursday.

In the short term, it can cause shortness of breath, coughing, sore throat and eye irritation, with symptoms potentially worsening in people with asthma or lung disease. It can also increase the risk of getting lung disease and respiratory infections, including COVID-19, according to the Centers for Disease Control and Prevention.

While research on the effect of wildfire smoke on COVID-19 is scant, hospitalizations for other respiratory infections typically increase during wildfire seasons, said Stephanie Christenson, an assistant professor of pulmonology at University of California San Francisco.

“We don’t know for sure if COVID-19 is going to be worse in the setting of wildfires, but we can speculate that is true,” she said.

“If you have inflammation from one thing like wildfires and you get COVID-19 on top of that also causing inflammation, that could compound each other and cause hospitalizations or other bad outcomes.”

Inflammation from wildfire smoke can last weeks or months, potentially delaying recovery for COVID-19 patients or making them sicker.

Mary Prunicki, director of air pollution and health research at the Sean N. Parker Center for Allergy and Asthma Research at Stanford, said the university hospital has seen increases in admissions for a variety of issues since the fires began.

Three weeks after the fires started, hospital admissions increased 17 percent for asthma, 14 percent for cardiovascular disorders, 43 percent for cerebrovascular disorders like strokes, 18 percent for kidney-related disorders and 15 percent for substance abuse disorders compared to three weeks before the fires, she said, citing an analysis by Stanford researcher Bibek Paudel.

Prunicki also said the elderly tend to have even worse outcomes and noted that socioeconomic factors can play a role in who is affected because people with more money can escape to other areas.

For those who can’t travel to safety, Prunicki said, fine particulate matter can cause issues because its small size allows it to reach many parts of the body.

“The majority of wildfire smoke is PM2.5, and the reason we care so much about it with human health is because it’s small enough — it’s like 1/30th the width of a human hair — it’s small enough that it can cross over into the bloodstream once it’s inhaled into the lungs, whereas bigger particles can’t do that. And so once it’s in the bloodstream it can cause problems in lots of … organs,” she said.

Studies have already linked long-term exposure to PM2.5 to worse coronavirus outcomes.

Researchers with the State University of New York (SUNY) linked exposure to a higher quantity of the substance to a 7 percent increase in mortality rate, while a Harvard study found that someone living in an area with a higher quantity had an 8 percent greater likelihood of dying from the virus.

Michael Peroni, who worked on the SUNY study, said that even though wildfires are shorter term events and his study looked at long-term exposure, he believed it can still be helpful in looking at wildfires because “more hazardous air pollutants and particulate matter that is in the air … is going to affect how us as a population are able to fight off these respiratory illnesses.”

Medical experts say the adverse effects of wildfire smoke on the immune system could also put people at greater risk of other illnesses.

“We don’t know much about coronavirus and wildfire smoke, but the data that we do have on wildfire smoke would suggest that it has the ability to suppress our immune system and leave us vulnerable to the coronavirus,” said Luke Montrose, an environmental toxicologist and assistant professor at Boise State University.

The combination of wildfires and COVID-19 is also creating challenges to the pandemic response. Illnesses caused by both can have similar symptoms, creating confusion about when people should get tested for COVID-19 or see a doctor.

Preventive measures are also becoming more complicated. While people are generally encouraged to engage in outdoor activities since the virus spreads more easily indoors, residents of areas with poor air quality are being asked to stay inside. The only masks that offer protection against both smoke particles and COVID-19 are N95 respirators, which are in shortage and typically reserved for health care workers.

Meanwhile, the coronavirus is making it harder to combat the fires, as volunteers who usually clear undergrowth and brush have had to stay home and firefighters face staff shortages due to infections.

“We have these massive amounts of smoke that are blanketing whole communities. There’s no way to get away from that smoke,” said Montrose. “The dose is high. The duration is long and the … frequency of exposure has been numerous.”