Humidifiers vs Dehumidifiers vs Purifiers: Which One Do I Actually Need?

A Tall Drink of Water

In the winter, if you’re spending most of your time cooped up inside next to heaters, your skin can become incredibly dry. It’s also common to experience dry eyes, chapped lips, or, worse, regular nosebleeds. A humidifier will add moisture to the air in your home, and can help those afflicted, according to Dr. Dawn Davis, a dermatologist at the Mayo Clinic in Rochester, Minn. While all humidifiers pull from a reservoir of water, they operate in one of two ways. Ultrasonic humidifiers use rapid vibrations to propel a mist of water into your air. Evaporative humidifiers, meanwhile, heat the water until it is steam, then use a fan to push it through a filter. Both types work, though ultrasonic ones, like this Levoit Classic 300s, tend to run more quietly and can be taken apart more easily for cleaning. Make sure to wipe down all parts of the humidifier daily and sanitize the tank with a vinegar solution at least every other week so no microorganisms can grow in the standing water.

For Swampy Days

While very moist environments are great for some tropical plants and our skin, organisms like dust mites and mold also find them hospitable. This can make humid environments unpleasant for folks with allergies or asthma, said Jose Jimenez, a chemistry professor at the University of Colorado Boulder. Mold growth can also damage your furniture, wallpaper and floors. With dehumidifiers, you again have two choices: Desiccant dehumidifiers absorb water using a material such as those silica gel packs that come with new shoes. Refrigerant ones, like the Frigidaire FFAD2233W1, use a fan to pull moist air in through a filter and pass it over a cold metal plate. After water in the air condenses onto this plate, it’s channeled into the device’s water tank. The handle on this Frigidaire model’s 22-pint tank makes it easy to dispose of this excess water, a big plus since you’ll be emptying the tank at least every day you use it. Clean it (and the filter) each time you use it.

Out, Damned Particulate!

Air purifiers—the marketing-friendly name for what some call “air cleaners”—are designed to remove pollutants, which can trigger respiratory issues. These irritants might result from household activities, like cooking with gas or lighting candles. Environmental factors, like Covid-19 or wildfire smoke, can also contribute. The best purifiers use high-efficiency particulate air (HEPA) filters, constructed from pleated fiberglass. These trap most particles that are larger than 0.3 microns. (Pollen, for context, is usually no smaller than 10 microns.) Commercial air purifiers, like this Coway Airmega AP-1512HH, use HEPA filters in conjunction with powerful fans that quickly suck in air and direct it through the filter. You could, Prof. Jimenez notes, approximate this by taping a HEPA filter from a hardware store to a box fan. But the Coway purifier is far more attractive, likely much quieter and can adapt its efforts to the amount of irritants it detects in your air.

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