I began researching humidifiers in New York City during the second-longest drought on record. In November my radiators clanked along, blasting my 100-plus-year-old Brooklyn apartment with heat. And according to the hygrometer on my indoor air quality monitors, my humidity was hovering at 32 percent. The inside of my nose was dry, as was my skin. My houseplants needed to be watered more than usual. Brooklyn’s Prospect Park had a wildfire that required more than 200 firefighters. This is all to say it was arid.
And parched interiors are not just about chapped lips or dry noses. According to the recommendation of Harvard’s School of Public Health, indoor humidity can slow the spread of Covid-19. Ideal indoor humidity should be between 30 percent and 50 percent. And studies suggest that a higher ambient humidity along with warmer temperatures also inhibit the spread of influenza. There’s a lot those little humidifiers can do.
And still, the number one abandoned appliance I see on my neighborhood’s stoops is the humble humidifier. Often, they are left with a Paddington Bear–style label with the words, “Still works!” I also see them discarded in the trash. And I, too, am guilty of throwing out more than one humidifier. I give up when I can’t seem to clean the gross brown film at the bottom of their tanks. I start out with good intentions, filling them with the recommended distilled water, but I’ll eventually switch to tap. I’ve gotten better and cleaned my last humidifier properly with water and citric acid, purchased at a spice store.
Still, the minerals in water are an issue. If you have hard water, your humidifier might produce a film of white-dust mineral buildup; that is why so many models recommend distilled water or come with filters. And I’ve gone through entire dry-air winters because I didn’t feel like dealing with a humidifier. For more on how to improve your indoor air quality, check out our guides to the Best Air Purifiers, Best Space Heaters, Best Dehumidifiers, Best Indoor Air Quality Monitors, and Best Fans.
Updated October 2025: We've added the Blueair DreamWell Humidifier, Blueair 2-in-1 Purify + Humidify, and Dreo Smart Humidifier 735S 11L, and ensured accurate links and prices throughout.