Do Air Purifiers Help With Wildfire Smoke?

Yes—air purifiers can reduce wildfire smoke indoors

A portable air purifier with a properly fitted, high-efficiency particle filter can reduce fine particles from wildfire smoke, including PM2.5, in the room where it runs. It cannot remove all smoke-related gases, protect you outdoors, or make a room safe if smoke levels are severe. Follow local health and emergency guidance, especially if authorities advise staying indoors or evacuating.

Which filters help with wildfire smoke?

• HEPA or high-efficiency particle filtration: The main feature to look for. It captures airborne particles, including much of the fine particulate matter in smoke. Check that the purifier is designed to use the filter and that air cannot bypass it around the edges.
• Activated carbon: Can reduce some odors and gases, but performance varies with the type and amount of carbon. A thin carbon-coated sheet may do less for odors than a filter containing more adsorbent material. Particle CADR does not tell you how well a unit removes gases.
• Ozone-generating features: Avoid devices that intentionally produce ozone. Ozone can irritate the lungs. If a purifier has ionizing, plasma, or similar features, check the manufacturer’s information and applicable safety guidance; choose a filtration-only setting if available.

Choose a purifier for the room

Check the purifier’s recommended room size and, when available, its smoke CADR (clean air delivery rate). CADR indicates how quickly a unit delivers filtered air for particles; a higher smoke CADR is generally more suitable for a larger room. Do not rely on a large maximum room-area claim if it assumes fewer air changes than you want. When uncertain, choose a unit sized conservatively for the room and run it at a speed you can tolerate.

Keep doors and windows closed when outdoor smoke is heavy, while following guidance about ventilation and indoor heat. Place the purifier where its intake and outlet are not blocked, and run it continuously during smoky conditions if the manufacturer allows. A portable unit works best in the room where people spend the most time; one purifier may not clean an entire home evenly.

Get the most from the filter

Check the filter on the schedule in the manual, and replace it when the manufacturer recommends or when it is damaged, heavily loaded, or causing airflow to drop. Smoke can load filters faster than ordinary household use. Do not wash a filter unless the instructions specifically say it is washable. Keep the pre-filter clean as directed, since a clogged pre-filter can restrict airflow.

A purifier is one part of reducing exposure. Avoid activities that add particles indoors, such as smoking, burning candles, or frying without ventilation. If you have central HVAC, use a compatible high-efficiency filter only if the system can handle it, and follow the HVAC manufacturer’s guidance. People with breathing or heart conditions should consult a healthcare professional about their individual precautions.