Protecting Indoor Air During Wildfire Smoke Events

Fine particulate matter from wildfire smoke can trigger shortness of breath, chest tightness, headaches, and irritation of the nose and eyes. When smoke combines with high temperatures, the health impact intensifies, increasing the likelihood of both short-term and chronic respiratory problems.

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Health officials advise staying indoors and maximizing filtration. Central air-conditioning systems should run on recirculate mode, with filters replaced on schedule. Filters rated MERV 13 or higher, or portable units equipped with HEPA filters, are most effective. Windows and vents that draw outdoor air should be closed, and any gaps sealed to prevent infiltration. When air-conditioning is unavailable, seeking clean, cool spaces such as libraries or malls is recommended.

Associated Press

A low-cost alternative uses a box fan paired with four 20-by-20-inch furnace filters rated MERV 13 or higher. The fan should blow outward, with filter arrows pointing inward, and the assembly taped airtight. The Environmental Protection Agency reports that this design removes fine particles as well as many commercial purifiers.

Associated Press

If mild symptoms appear, the advised response is to move indoors and limit exposure to additional pollutants such as candles, fireplaces, or gas stoves. Persistent wheezing, severe breathlessness, or distress warrants immediate emergency care.

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• “The basic message is that something is better than nothing,” — Amy Kalkbrenner, environmental epidemiologist, University of Wisconsin-Milwaukee

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• “The good news is they really work,” — Amy Kalkbrenner

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• “When smoke and heat occur together, the impacts on your health are even greater than when they occur by themselves,” — Jess Downey, researcher, University of Oregon’s Center for Wildfire Smoke Research and Practice

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• “Being from Chicago, I think you can liken it to trying to keep the cold air out,” — Dr. Khalilah Gates, lung doctor, Northwestern Medicine

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• “When you ever start to feel those symptoms and they’re not severe, it’s important to acknowledge, ‘Oh, my body is responding to this. I need to move away from it. I need to move inside,’” — Dr. Khalilah Gates

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