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Best prescription for avoiding wildfire smoke: Stay inside

OHSU expert warns that cloth masks are insufficient for wildfire smoke, may give false sense of security
Wildfire smoke in a neighborhood.
Portland residents step outside to view the wildfire smoke casting a colored haze over the west side, September 9, 2020. (OHSU/Kristyna Wentz-Graff)

As smoke from large wildfires burning in Eastern and Southern Oregon, as well as neighboring states, creates poor air quality, experts from Oregon Health & Science University warn that people should stay indoors to avoid dangerous particulate matter — and that advice holds for both at-risk and healthy people.

Gopal Allada, M.D., stands outside, smiling.
Gopal Allada, M.D., (OHSU)

Gopal Allada, M.D., associate professor of medicine (pulmonary and critical care) in the OHSU School of Medicine, warns that wearing a cloth mask outside won’t sufficiently protect people from the microscopic particulate matter that comes from wildfire smoke. N95 masks are the gold standard.

However, the best protection from wildfire smoke is to limit time outdoors, he said.

“A cloth mask, wet towel or bandana are not designed to protect you from fine particulate matter entering the lungs,” Allada said. “Even worse, these could give people a false sense of security that it’s safe to stay outside longer than they should.”

Questions and answers

Q. Why is wildfire smoke bad for my health?

A: Wildfire smoke is a mixture of gases and fine particles from burning trees and plants. Smoke can irritate sinuses and lungs and is known to trigger exacerbations in patients with underlying lung disease such as asthma, chronic obstructive pulmonary disease (COPD), or cystic fibrosis. Your risk is dependent on the amount and length of time you are exposed as well as your overall general health.

Q: What is particulate matter?

A: The particulate matter in wildfire smoke poses the biggest risk to your health. Particles larger than 10 micrometers irritate your eyes, sinuses and throat. However, particles around 2.5 micrometers are inhaled all the way into your lungs and trigger inflammation. The size of the particle matters because you must have the right protective wear to prevent these super small-sized particles from causing harm.

Q: How can I protect myself from smoke?

A: Here are some strategies to help you:

  • Stay indoors when possible with the doors and windows closed.
  • Reduce sources of indoor air pollution such as smoke from tobacco, wood-burning stoves, and candles.
  • Use high-efficiency (HEPA) air-cleaning filters to help indoor airborne irritants.
  • Avoid vacuuming, which can stir up dust.
  • When driving in a vehicle, keep windows closed with the air conditioning set to recirculate.
  • Drink plenty of water to help reduce symptoms of scratchy throat and coughing.

Q: Should I wear a mask/respirator, and if so, what type will protect me best?

A: Remember that staying away from smoke is the best protection. There are some masks that are more effective than others.

  • N95 respirator. This will filter 95% of smoke particles, though some gases can get through. This is one of the best available masks if fitted and worn properly.
  • “Dust” or “surgical” masks. These masks are NOT designed to filter particulate matter that is harmful to your lungs. Therefore, we would not recommend these.
  • Wet towel or bandana. Like dust masks, these are not designed to protect particulate matter from entering the lungs. They may help with your mouth and sinuses, but give you a false sense of security for your lungs.


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