How to Protect Yourself From Wildfire Smoke

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People in the path of wildfire smoke can take certain precautionary measures to protect their lungs from smoke pollution. Older people, children and individuals with heart or respiratory conditions in particular are advised to filter air, limit outside activities or otherwise temporarily leave the affected area.

Children are especially sensitive to smoke pollution because their airways are still developing and they breathe more air per pound of body weight than adults, according to the federal Centers for Disease Control and Prevention (CDC).

Here are the steps you can take to protect yourself and your loved ones from the dangers of wildfire smoke:

• Check local air-quality reports. For real-time updates on the air quality in your neighborhood, plug in your ZIP code at the Environmental Protection Agency’s AirNow website.

• Keep indoor air clean. Keep your house and car windows closed. Run an air conditioner, but keep the fresh-air intake closed to prevent outdoor smoke from infiltrating inside. To reduce exposure to smoke and smoke residue, the California Air Resources Board recommends mechanical air cleaners with a high-efficiency particulate air (HEPA) filter that collects very small particles and does not emit ozone or other harmful substances. These air cleaners can dramatically reduce indoor particle levels, in some cases by more than 90%. See devices that are certified by and legal in California.

• In homes without air-conditioning, keep doors and windows closed. This can reduce pollutant levels by 50% (PDF).

• Avoid activities that increase indoor pollution. Burning candles, cooking on gas stoves and vacuuming can increase indoor pollution.

• Wash your nose out and gargle with clean water. Do this five times a day until the smoke subsides.

• Take a shower and wash your clothing after being outside.

• Wear a respirator mask if it helps you feel better, but choose carefully. Hardware stores and pharmacies sell N95 masks that filter out fine particles. Public safety officials caution that these masks don’t work well for everyone and are no substitute for spending as much time as you can indoors with sealed windows. The least effective options are one‐strap paper dust masks or surgical masks that hook around your ears — they don’t protect against fine particles.

• Note that a cloth mask, such as those often used to prevent the spread of COVID-19, will not adequately protect lungs from particles found in wildfire smoke.

What’s in wildfire smoke?

Wildfire smoke (PDF) is a shifting blend of gases and particles, including carbon dioxide, water vapor, carbon monoxide, hydrocarbons and other organic chemicals, nitrogen oxides and trace minerals. There are thousands of individual compounds, many of them toxic.

But what worries doctors most is the particulate matter in smoke, the tiny bits of feathery ash and dust-like soot, much of it invisible to the eye. They are especially worried about particulate matter less than 10 microns wide, known as PM 10. (By comparison, a human hair is about 60 microns wide.) They also dread the subset known as PM 2.5, for particulate matter less than 2.5 microns wide.

These tiny particles travel deep into the lungs, and the smallest ones can even enter the bloodstream. The smallest particles are also the lightest, and can travel vast distances on the wind.

The particles first damage the body simply by getting inside it, triggering inflammatory reactions that themselves can trigger breathing difficulties, heart attacks and even strokes. Within a few days of smoke exposure, damaged lungs can succumb to bronchitis or pneumonia. In pregnant people, exposure to particulates has been associated with premature birth and low birth weight in infants.

A version of this story was first published on Aug. 7, 2018.