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Air Conditioner David Mercer/AP Photo

In this Wednesday, Sept. 18, 2013 photo, a newly installed air conditioner sits in a window of a classroom at Bement Elementary School in Bement, Ill.

August 11, 2017

Why your air conditioner may be flaring up your allergies

After a month of enduring brutal heat in the second-floor bedroom of my South Philadelphia row home, I finally installed a window air conditioner unit. At first, it meant sweet relief.

But after about a week, every morning after leaving the air conditioner on overnight, I would wake up with the same symptoms: a stuffy nose, cough and dried-out throat. What gives?

Turns out, air conditioners — especially if not cleaned out properly – can cause your allergies to flare up.

Dr. John Ohman, an allergy doctor at Tufts Medical Center in Boston, recently noted to The New York Times that just walking into a dry, cold room can cause a runny nose.

Specifically, regarding air conditioners, the Times explained how particles in the air can get trapped in their filters, triggering symptoms for those with allergies.

Those with allergies might develop congestion because small particles like pollen, mold spores, pollutants and dust mites can get trapped by air-conditioning filters and then released into the air when the machine is turned on, said Dr. Maria Garcia-Lloret, an allergist at the U.C.L.A. School of Medicine. Pollutants and bacteria wouldn’t cause an allergic reaction per se, she said, but could irritate the nose. Exposure to mold spores can cause allergic reactions that may be particularly long-lasting.

Air conditioners, if kept clean, can actually help prevent allergies. A Penn Medicine blog post from last year said that opening your windows during the warmer months can invite pollens that cause allergic reactions. By using a HEPA (high-efficiency particulate air)-certified air conditioner filter and changing it regularly, you can improve the air quality in your home.

“It’s important to remember to clean or replace your filters regularly to keep your air free from allergens,” Dr. Paula Barry, a physician at Penn Family and Internal Medicine Longwood, said in a similar blog post this year.

If you want to clean out your window unit, how to do so may vary depending on your model, but there are plenty of simple tutorials on YouTube, including more thorough instructions on cleaning your entire unit and simpler ones on just cleaning the filter.