Top Reasons to Buy a Cool

They’re safer around kids and pets. And they provide other benefits.

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Cool-mist humidifiers are the choice of most Americans seeking to improve the dryness in their homes. These machines dominate the market because they pose fewer safety risks than warm-mist humidifiers, aka vaporizers.

Unlike warm-mist humidifiers, cool-mist versions add moisture to indoor air without boiling water and producing steam. With no potential to burn or scald, cool-mist humidifiers are the only humidifier type that pediatricians recommend for households with babies and young children.

“They’re also the best choice for homes with pets prone to investigating mysterious appliances,” says Misha Kollontai, who leads humidifier testing at Consumer Reports. Translation: They’ll save your sniffing Snoopy’s snout.

Read more on the advantages of cool-mist humidifiers below, and see the best cool-mist models among each of the humidifier sizes Consumer Reports tests. ​​For test results and more options, CR members can check our complete humidifier ratings, which include units that range from personal size all the way up to consoles that can humidify 1,000 square feet or more.

Even in homes without curious critters or toddling tots, cool-mist humidifiers have benefits. Here’s how they excel over other types.

Energy efficiency: Cool-mist models use significantly less energy than warm-mist models. The reason is that they work without boiling water, which requires a fair amount of electricity, Kollontai says. Depending on the unit’s style, a cool-mist humidifier uses one of two mechanisms to add moisture to the air.

Evaporative cool-mist humidifiers use a fan to blow air through a wet wick; the air cools as it picks up moisture from the wick. Periodically, you’ll need to replace a filter or wick, which can run from $10 to $20.

Ultrasonic cool-mist models—a majority of units in CR’s ratings—use small vibrating diaphragms called nebulizers to create a mist. Ultrasonic units typically are less noisy than evaporative models because they have no fan. But their mist can leave a white dust—tiny particles of mineral precipitate—on surfaces. (To prevent that dust, you can use distilled or filtered water instead of tap water.)

Help for stuffy noses: Cool mist can help shrink swelling in nasal passages, making breathing easier, according to the Food and Drug Administration. By contrast, warm mist can cause nasal passages to swell, making breathing more difficult, another reason the FDA doesn’t recommend their use for infants with coughs and colds.

Convenience in small sizes: In our ratings of small humidifiers, cool-mist models were judged more convenient as a whole vs. small warm-mist units—better known as vaporizers—reflecting factors such as ease of operation. Several small cool-mist units in our ratings have humidistats, which turn off the unit when the air reaches a set humidity level; none of the small vaporizers in our ratings have that feature. Small vaporizers typically don’t even have a power switch; they start working when you plug them into an outlet. (They do, however, shut off automatically when the tank is empty.)

More shopping choices: Cool-mist models make up more of the portable humidifier market than other types, says Marion Wilson-Spencer, a market analyst who covers humidifiers for Consumer Reports. In CR’s ratings, you can find cool-mist humidifiers in every size we test, including travel models, units for small, medium, and large rooms, and consoles for very large rooms of 1,000 square feet or more. In our ratings, you won’t find warm-mist units in travel or console sizes; you also won’t find dual-mist units in small, medium, or travel sizes.

One area where cool-mist humidifiers have no edge is in how well they do their basic job: adding moisture to the air. “Cool- and warm-mist units are equally effective at humidifying,” Kollontai says.

There’s also no way to generalize about which type is easier to clean. “It depends largely on the design,” Kollontai says. With either type, though, it’s crucial to clean the components regularly to prevent the growth of mold spores and other nasties that can lead to illness. Check the manufacturer’s directions for cleaning, as well as Consumer Reports’ advice on this key task.

The main reason for using a warm-mist humidifier is noise. Warm-mist models tend to be quieter because they don’t need a fan, nebulizer, or vibrating diaphragm to move moisture into the air. “The steam naturally escapes the tank,” Kollontai says.

For the best of both worlds, consider buying a dual-mist version, which lets you choose between cool and warm mist. There are nine dual-mist units in CR’s ratings, all of them meant for large rooms of 500 to 999 square feet. Five of them have very good Overall Scores. “A dual-mist model allows you to take advantage of the soothing warm mist only when you truly think you need it, and to take advantage of the energy savings of cool otherwise,” Kollontai says.

Just steer clear of dual-mist units if you have kids or pets, because an inadvertent turn of the dial or press of a button can activate potentially scalding steam.

Choose the size that’s closest to the square footage of the space you want to humidify.

Tobie Stanger

Tobie Stanger is a senior editor at Consumer Reports, where she has been helping readers shop wisely, save money, and avoid scams for more than 30 years. Most recently, her home- and shopping-related beats have included appliance and grocery stores, generators, homeowners and flood insurance, humidifiers, lawn mowers, and luggage—she also covers home improvement products like flooring, roofing, and siding. During off-hours, she works on her own fixer-upper and gets her hands dirty in the garden. Follow her on Twitter @TobieStanger.