Wildfire Smoke Increases the Risk of Contracting Covid-19

One study identified a link between the 2020 wildfires in California, Oregon and Washington State and an increase of Covid cases and deaths. 

(Bloomberg) — As the world warms, disasters collide. That’s happening right now, as health experts warn that  exposure to wildfire smoke across North America increases the risks of catching Covid-19 and worsens the impacts for people who already have or are particularly susceptible to the virus.“Exposure to air pollution from wildfire smoke can increase susceptibility to Covid and other respiratory diseases,” says Kristie Ebi, a climate and health professor at the University of Washington.Here’s how it works: Wildfire smoke contains very small particles called PM 2.5, which can get inhaled and stuck in the body, causing irritation and ultimately affecting the immune system. These particles can “make you more prone to lung infections, including SARS-CoV-2, the virus that causes Covid-19,” warns the Centers for Disease Control and Prevention on its Wildfire Smoke and Covid-19 webpage.This means the millions of people in Canada and the US are currently at an elevated risk of catching Covid, thanks to the smoke from hundreds of wildfires raging in Canada. For three days this week, air quality in New York City was among the worst in the world, according to the World Air Quality Index. Many cities and states have issued air alerts because of the smoke, which isn’t expected to clear up until early next week. Poor air quality has also resulted in the grounding of flights, cancellation of Major League Baseball games and other local disruptions.

People who are already suffering from Covid are also at greater risk of experiencing the myriad health impacts associated with short-term exposure to wildfire smoke, including but not limited to: coughing, scratchy throat, runny nose, chest pain, headaches, asthma attacks, fatigue, wheezing and breathing difficulties, and heart attacks.

“In other words, it’s easier to get sick and harder to fight the sickness,” said Francesca Dominici, a Harvard data scientist.

One 2022 study out of Harvard University, which Dominici co-authored, estimated just how deadly the link between Covid and wildfires can be. It found that PM2.5 emissions from the 2020 wildfires in California, Oregon and Washington were associated with an 11.7% increase in Covid cases, and an 8.4% increase in Covid deaths, though Dominici caveats that this was before the proliferation of Covid vaccines. 

Although the US Covid Public Health Emergency technically ended in May, the virus continues to infect and kill people across the country — and the globe. More than 1 million people have died from the virus in the US to date, and there have been thousands of Covid-related hospitalizations this week.

Many of the precautions that became familiar to people during the worst of Covid are also relevant protections against wildfire smoke. That includes wearing a high-quality mask — in the case of smoke, while outdoors and when driving or taking public transit — and being more proactive when it comes to indoor air quality. 

To avoid exposure to wildfire smoke, people are frequently encouraged to go indoors and close windows. But that guidance assumes “your indoor air environment is necessarily cleaner than your outdoor environment,” says Luke Montrose, an assistant professor and environmental toxicologist at Colorado State University. For many people, this isn’t the case: Montrose’s research has found that smoke can get indoors even when windows are shut. 

Public health experts advise investing in an indoor air purifier, such as a HEPA filter, or what’s known as a Coris-Rosenthal Box — essentially a DIY purifier that can be built on the cheap. To keep tabs on indoor air quality, it’s also worth considering buying an air-quality monitor. California’s South Coast Air Quality Management District has an extensive guide to monitors at various price points.

(Updates with comment from Francesca Dominici in sixth paragraph, and details on tactics for improving indoor air quality.)

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