Keeping Indoor Air Clean When Wildfires Rage

When a wildfire smokes out the sky, the orange‑hued light may look dramatic, but the real danger is invisible: tiny particles that slip through cracks and linger in our homes. Those specks can irritate lungs, trigger asthma, and even affect heart health.

First thing’s first—don’t panic, just close the doors. Keep windows shut as tightly as you can, and pull any screens aside. It sounds obvious, but an open sash is an easy invitation for polluted air.

If you have central air conditioning, treat it like a frontline defender. Change the filter according to the manufacturer’s schedule, but during a smoke event, opt for the best you can fit. Filters rated MERV 13 or higher trap the fine particles that cause most trouble. Set the system to recirculate rather than pulling in fresh outdoor air, and, if possible, close the exterior vents that draw from the outside.

The University of Oregon’s Center for Wildfire Smoke Research advises running the fan continuously throughout the smoke episode—not just when you need cooling. It may add a few cents to the electric bill, but it keeps the air moving through that high‑efficiency filter, which is worth the extra cost.

For homes without central HVAC, portable air cleaners are a lifesaver. Look for units that boast a true HEPA filter (the kind that captures 99.97 % of particles down to 0.3 microns) or a certified “smoke‑removing” label. Place the purifier in the room you spend most time in—usually the bedroom or living area—and run it on the highest fan setting while the smoke persists.

Don’t forget about the small but useful extras. An activated‑carbon filter can mop up odors and certain gases that HEPA alone can’t catch. If your furnace has a built‑in carbon stage, make sure it’s installed correctly.

While you’re sealing the house, try to limit indoor activities that generate extra particles: skip frying, avoid burning candles, and keep smoking to a strict outdoor‑only rule. Even dusting can raise the particle count, so use a damp cloth instead of a dry duster.

Keep an eye on the Air Quality Index (AQI) for your zip code—most smartphones and weather apps show it now. When the AQI climbs above 150 (unhealthy), it’s a clear sign to stay indoors and run your filtration gear nonstop.

Lastly, consider a simple humidity boost. A modestly humid environment (30‑40 % relative humidity) helps particles settle faster, but avoid over‑humidifying, which can encourage mold growth.

By combining these steps—tightening the building envelope, upgrading filters, using HEPA purifiers, and staying aware of outdoor conditions—you can breathe easier even when the sky outside looks like a distant memory of blue.