Yes. Doctors often recommend humidifiers in the winter because the dry, heated air in homes can irritate your nose and throat. But, while those symptoms can be annoying, "there is no evidence I know of that humidifying air reduces colds," said Dr. Ralph Metson, a sinus surgeon at the Massachusetts Eye and Ear Infirmary.
Humidifiers can be a breeding ground for mold and bacteria. Indeed, on its website, the Mayo Clinic notes that while humidifiers may be "soothing" for people who have asthma flare-ups because of dry indoor air, "dirty humidifiers can create more problems than they solve."
If you do choose to use one, make sure you pick the right kind, and buy an instrument called a hygrometer (they cost as little as $10) that measures humidity in the air. Ideally, humidity should not go above about 35 percent, said Jeffrey C. May, a chemist-turned-building investigator who is also the author of "The Mold Survival Guide."
The ones that use steam or boiled water are less likely to breed mold than the ones that use cool mist, but the hot ones also pose a scalding risk.
It's crucial to wash all humidifiers according to the instructions to prevent microbial growth in the water. If you don't clean your humidifier as the instructions recommend, "you're blowing stuff into the environment that is not good," said Dr. John Ouellette, a retired allergist from Madison, Wis., who collaborates with May.
JUDY FOREMAN
E-mail health questions to foreman@globe.com.
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