Can a Face Mask Protect You Against Wildfire Smoke? What Doctors Say

Nov 27, 2023

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Wildfires continue to burn in Canada, causing smoke to drift south into some parts of the U.S. That smoke has brought down air quality across the eastern seaboard and other areas, stretching into the Midwest and as far south as the Carolinas.

Air quality has gotten really bad in some areas. Air monitoring company IQAir reports that Detroit currently has the third-worst air quality of any city in the world, while New York City is ranked fifth. New York City mayor Eric Adams recommended yesterday on Twitter that residents "try to limit your outdoor activities today to the absolute necessities."

Doctors are echoing that sentiment. "For the next couple of days, I’ve recommended that my patients stay indoors as much as possible," says Jorge Mercado, M.D., associate chief of pulmonary, critical care, and sleep medicine at NYU Langone Hospital—Brooklyn.

Still, most people need to go outside at some point, whether it's to go to work, school, or the grocery store. With that, it's understandable to wonder about how to stay safe when you’re outdoors.

Public health officials and doctors have made it very clear that breathing in wildfire smoke is bad for your health. So, can a face mask help protect you? Here's what you should know.

Wildfire smoke is a mixture of gases and fine particles from burning vegetation, parts of buildings, and other materials, according to the Centers for Disease Control and Prevention (CDC). Breathing in this smoke can cause these immediate health issues:

Coughing

Trouble breathing normally

Stinging eyes

A scratchy throat

Runny nose

Irritated sinuses

Wheezing and shortness of breath

Chest pain

Headaches

An asthma attack

Tiredness

Fast heartbeat

What's more, experts say prolonged exposure to wildfire smoke can eventually inflame your lungs, potentially leading to thickening or scarring. The fine particles can also worsen the symptoms of chronic heart and lung diseases, and make you more susceptible to lung infections, including COVID-19, according to the CDC.

"Exposure to wildfire smoke is dangerous to everyone, but it's even more dangerous to some groups," says Peter DeCarlo, Ph.D., an associate professor of Environmental Health and Engineering at Johns Hopkins University. "Children whose bodies and lungs are developing are more susceptible and the elderly. The other group that is susceptible is people with pre-existing respiratory and lung conditions. They can be triggered by high levels of air pollution, which is what wildfire smoke is."

An N95 mask "will offer some protection," when it's worn properly, the CDC says. N95 masks filter out up to 95% of airborne particles, including the microscopic ones in wildfire smoke, which are known to travel deeply into the lungs.

"Unfortunately, there is no completely safe mask unless you go to a self-contained respirator, which some firefighters are using," says Raymond Casciari, M.D., a pulmonologist at St. Joseph Hospital in Orange, Calif. "But they’re extremely hot, extremely heavy, and not the kind of thing you can wear for eight hours a day."

"N95 masks can filter out 95% of the particulate matter in wildfire smoke, but the masks don't offer complete protection," says Glenn VanOtteren, M.D., division chief for pulmonology at Corewell Health. "There can still be inhalation of irritating gases and vapors."

Still, fit matters. "If it's properly fitted and sealed well on your face, it will take out a pretty significant chunk of air pollution," DeCarlo says. "It will definitely offer more protection than not wearing a mask."

Fady Youssef, M.D., a board-certified pulmonologist, internist, and critical care specialist at MemorialCare Long Beach Medical Center in Long Beach, Calif., recommends keeping tabs on your air quality by checking AirNow, which is a government website that provides data on air quality by zip code, and deciding on whether to wear a mask based on that. "Typically, from zero to 100 is within an acceptable range," he says. "If it's more than 100, it is not advised for patients with lung disease to go outside." If it's on the higher end, such as an "unhealthy" rating (which is above 150) or the air is clearly smoggy, everyone should consider wearing a mask, he says.

Can a KN95 mask protect you from wildfire smoke?

While N95 masks are in good supply now after being scarce during the height of the COVID-19 pandemic, you may still have a KN95 mask laying around and wonder if it’ll help with wildfire smoke. Dr. Casciari says you could try a KN95 mask, which is China's version of the N95—just know that they don't meet the same standards as an N95. Jonathan Parsons, M.D., a pulmonologist at The Ohio State University Wexner Medical Center, agrees. "There are some very subtle differences, but essentially they are equivalent in terms of protection from smoke exposure," he says.

That said, make sure you are purchasing your mask from a trusted retailer. "A lot of KN95s have been reported as counterfeit, so they do not provide the protection for which they indicate," says Mitchel Rosen, Ph.D., an associate professor at the Rutgers School of Public Health. (Check out these tips from the CDC on how to spot a counterfeit mask.)

Ultimately, a close fit is really important, DeCarlo says. "If you have ways for the air to go around and not through the mask, that air will not be filtered," he says.

Not really. The CDC warns that cloth face masks "offer little protection" against wildfire smoke and "they do not catch small, harmful particles in smoke that can harm your health." But Dr. Casciari adds that cloth masks "still filter out the ash and bigger particles," and "there's something to be said for that."

Dr. Mercado points out that cloth masks were controversial even during the pandemic. "If you have a choice and it's not an emergency, I would prefer an N95 or surgical mask over a cloth mask," he says. But if it's the only thing you have access to, he says it's better than nothing.

Beyond wearing a face mask when necessary, you can potentially lower your exposure to wildfire smoke with a few extra precautions. The CDC specifically recommends the following:

Stay indoors, and keep your windows and doors closed.

Limit outdoor exercise when it's smoky, or choose lower-intensity activities to reduce your exposure to smoke. ("When you exercise, you’re breathing in large quantities of air and bringing it into deeper parts of the lungs," Dr. Casciari says.)

Avoid activities that create more indoor and outdoor air pollution, like frying foods, sweeping, vacuuming, and using gas-powered appliances.

Change your air conditioning settings to recirculate air, rather than pulling it in from outside.

Use a portable air purifier with a HEPA filter in one or more rooms in your home.

"I recommend not going outside, if you can," DeCarlo says. Staying hydrated is also important, Dr. Casciari says. Drinking plenty of liquids helps your body create mucus, which can then trap pollutants. "You want your body to keep making mucus," he says. "That's one of the defenses that your lungs have."

Ultimately, it's really best to be indoors as much as you can. "If your eyes are burning from smoke, that means your lungs are burning, too," he says. "That's a good way to tell if it's time to go indoors."

DeCarlo says smoky conditions should improve for the U.S. by the weekend. "The problem is the fire making the pollution, as well as weather systems bringing it into the easter seaboard," he says. "It will push out in a few days."

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