Do Air-Conditioners Filter Wildfire Smoke or Make Air Quality Worse?

An air purifier, like one that uses a HEPA filter, is the best way to improve the quality of your indoor air — but if you are staying inside to avoid wildfire smoke and don’t have access to an air filter, there are a few other things you can do to keep the air in your home as clean as possible.

The next best tool after an air purifier is an air-conditioner, said Dr. Panagis Galiatsatos, a pulmonary and critical care medicine physician at Johns Hopkins Medicine. Keep your windows closed, and make sure your air-conditioner is set to recirculate air, said Dr. Samantha Green, a family physician at Unity Health Toronto. You may want to replace the air filter in your central air-conditioner. Wirecutter, a New York Times company, has guidance on the air filters and purifiers that can help protect against wildfire smoke, and a tutorial on how to create a D.I.Y. air purifier.

If you don’t have air-conditioning, portable fans and ceiling fans can help. Keep fans close to where you are inside — and if you happen to have multiple fans, turn on all of them. “Anything that can help circulate the air is better than nothing,” Dr. Galiatsatos said.

You should keep bathroom exhaust fans off as much as possible if they bring in outdoor air, Dr. Green said. Some range hoods over kitchen stoves also allow outside air to infiltrate your home (if you’re cooking, you should use the range hood but try to limit the amount of time it’s on).

To further minimize the pollutants in the air, don’t burn candles or light a fire, and refrain from frying meat. Smoking indoors is always a bad idea, Dr. Galiatsatos said, but particularly when you’re already susceptible to exposure from wildfire smoke. “Now is the time to promote lung health,” he said.