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When wildfires fill the sky, it’s tempting to think your air-conditioner is taking care of the smoke as it cools the room. The truth is, the fine ash slips through most standard filters and lingers inside. Understanding this blind spot is the first step toward fresher indoor air.
Wildfire smoke is full of tiny bits of ash and chemicals that can go deep into the lungs and irritate the eyes, nose, and throat. For anyone with asthma, heart disease, or just sensitive airways, even a short spell of smoky air can trigger coughing, wheezing, or chest tightness. Knowing the risk is the first step to keeping that smoke out of your home.
Smoke sneaks through gaps in doors and windows, drifts in through vents, and rides the airflow of bath fans and range hoods. Once it’s inside, the fine ash hangs in the air or settles on furniture, leaving a thin gray dust. Because you can’t seal every crack, the real goal is to clear away the smoke that makes it indoors.
A central AC can help recirculate air, but only if used properly. The EPA advises closing any fresh-air intake and switching the system to “recirculate” mode. Then, install the best filter the unit can handle. Using a MERV-13 filter (or the highest rating your system allows) will trap most smoke particles. Make sure the fan runs continuously (set it to “On” rather than “Auto”) so air keeps moving through the filter.
Window or portable AC units usually have only a basic filter (if any). This means they do very little cleaning — on recirculate they just move the same air around. In fact, portable ACs that vent outside can pull smoky air in. The Lung Association warns not to use a window/portable AC with an outside intake in smoky conditions. If you must use one, keep it on the indoor-only setting and rely on other filters to clean the air.
You can lower smoke levels inside by using strong filters and a few easy habits. Key steps include:
Doing all of the above will clean the air far better than an AC alone. Each extra filter or purifier step helps reduce indoor smoke.
When wildfire smoke rolls in, experts recommend using high-quality filters. Filterbuy's MERV-13 and HEPA furnace and AC filters trap even the smallest particles effectively—and they're all made in the USA. Plus, Filterbuy provides quick shipping and custom sizing to fit your exact system. Customers love the brand, giving plenty of five-star reviews. They also appreciate the subscription service, which conveniently sends new filters straight to your door on schedule. Choosing a reliable, sturdy filter from Filterbuy can significantly improve your home's air quality during wildfire season.
Yes—keep doors and windows shut, set the system to recirculate, and let the fan run nonstop so the air keeps moving through the filter.
A MERV-13 (or higher) filter captures most tiny smoke particles far better than standard options.
Absolutely; recirculating stops the unit from pulling fresh outdoor air that could be full of smoke.
Check it every few days and replace it whenever it appears gray or clogged—sometimes every two weeks in extreme conditions.
Not much; most window units have thin filters that only move the air around without trapping the fine soot.
Models with a single exhaust hose can pull smoky air indoors; dual-hose units work better but still need a tight window seal.
Yes—a portable HEPA purifier adds another layer of cleanup, especially in rooms where you spend the most time.
No, it misses the smallest particles that cause the haze and odor, so upgrading is worth it.
Look for a dark gray surface or slower airflow; if in doubt, replace it—clean filters work best.
Use the highest MERV rating it can handle, seal any leaks, and run a separate HEPA purifier to pick up the slack.
