Will a COVID mask protect you from wildfire smoke?

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(KTLA) – As drought-plagued Western states enter peak wildfire season, you may be wondering if all those COVID-19 masks you have laying around will also protect you from fire smoke.

The short answer: It depends.

What are some of the harmful effects of wildfire smoke?

The contaminants in wildfire smoke, especially the smaller PM 2.5 particles that penetrate deeply into the lungs, may impair the body’s natural defense and clearance mechanisms. For this reason, people exposed to the wildfire smoke may be more likely to get infections after exposure and might even become more ill after infection, according to Dr. Richard Castriotta, a pulmonologist with Keck Medicine of USC.

Those with asthma may develop worsening bronchoconstriction and need more medications.

“Every wildfire is somewhat similar in terms of burning of plants and trees and so forth,” said Ed Avol, professor of clinical preventive medicine at the USC Keck School of Medicine. “Obviously, each specific fire can be quite different, depending on what is consumed. For example, buildings, or particular commodities such as cars or fuel or solvents and products that you might have in the garage, or plastics and so forth.”

So there are some specialty aspects, but in general, wildfire smoke is usually thought of as containing a number of high-concentration, different-sized particles and a wide range of different kinds of gases, he added.

“Generally, breathing smoke is not healthy for any of us,” Avol said. “But there are susceptible subgroups in our population at especially high risk.”

Those include young children, pregnant mothers, patients with heart disease, asthma and with pre-existing respiratory disease such as chronic obstructive pulmonary disease or pulmonary fibrosis.

So do COVID masks protect you from fire smoke?

Yes, N95 respirator masks are best and they do protect from wildfire contaminants, Castriotta said.

Avol, who studies air pollution and respiratory health and lung health development, echoed the sentiment.

“The so-called N95 masks, which are certified masks that have been measured and are produced in a fairly careful way and tested — assuming they fit your face properly — do a good job of protecting you from the particles in the air,” Avol said.

A regular cloth mask doesn’t do a very good job, he added, depending on what kind of cloth it’s made of and how it’s manufactured.

And as for the surgical masks (which are generally those loose-fitting, blue disposable ones), they “may do something to protect you against COVID, but it doesn’t work very well against wildfire smoke,” Avol said.

What’s the best way to protect yourself from wildfire smoke?

The best way to protect yourself from wildfire smoke is to minimize exposure to the extent that you can, which might mean staying indoors with the windows and doors shut.

Additional measures to take include:

Stay inside with a good air conditioning system.
Use a HEPA filter or air purifier with the air conditioner for added protection.
Place wet rags on the floor and at the window interface so that the air doesn’t come through underneath.
When going outside, wear an N95 mask for optimal protection
If you’re in a car, keep the windows rolled up and have a car ventilation system operate and recirculate.
Restrict physical activity so that you don’t increase your breathing rate and take in more air.

“Generally speaking, exercise is great for you but under these conditions where it might be smoky … we have to be a little more thoughtful about where and how and when we exercise,” Avol explained.

Checking the air quality index is helpful before going outside to do any exercise or work, he added. It can help make more informed decisions about whether to wear a mask or take “some sort of careful avoidance procedures to take care of our health because there are both short term and long term effects that we want to try to avoid.”