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Who needs a humidifier? 1/11
(This article is adapted from the January 2011 Consumer Reports magazine.)

Anyone who has uncomfortably dry or itchy eyes, throat or skin, or whose asthma is a problem indoors during the heating season, should consider getting a humidifier. Also if your baby or child has a cold or cough, the moist air a humidifier produces can help loosen congestion to help him breathe better, which is why your pediatrician might recommend buying one.

Ideally, indoor humidity should be 30 to 50 percent. But that level can drop significantly in winter, since cold air holds less moisture, and heating makes it even drier.

In addition to the health benefits, a humidifier can also reduce static electricity, peeling wallpaper, and cracks in paint and furniture.

Green recommendations

For smaller spaces, the Safety 1st Ultrasonic 360, a CR Best Buy, at $30, is designed for relatively small 330-square-foot areas. The pricier Air-O-Swiss A0S7135, $170, and Vicks V4500, $65, can cover more space and have a humidistat that automatically shuts them off when they reach a level set.

But if you buy a humidifier, whether it is a cool or warm-mist model, you need to commit to cleaning and disinfecting it regularly, or else you might end up with more problems from mold and mildew than you started with from dry air.

Cleaner humidifier, cleaner air

The more you use a humidifier, the more vigilant you must be. That’s because mold can grow within 48 hours on wet surfaces, and mold in the tank or in the water can then be transferred into the air, potentially causing itchy eyes and breathing troubles.

Even units with antimicrobial finishes on tanks and wicks will become scaly and moldy if they’re not cleaned. The Sharper Image HD10, at $55, features "Clean Mist Technology" that’s supposed to "prevent microbial growth on the surface of the water tank."

But Consumer Reports tests revealed plenty of bacteria inside. That’s why regular maintenance is critical for all humidifiers; that typically includes changing the water daily and disinfecting the tank weekly.

For the best results, follow these tips:

• Change the water daily. Empty the tank, dry all interior surfaces, and refill with clean water.

• Clean your humidifier often. Although some parts may be washable in the dishwasher, they still may need to be de-scaled with vinegar and disinfected with bleach. Check the owner’s manual and follow the manufacturer’s directions and schedule for de-scaling and disinfecting parts and replacing filters and wicks.

• Be aware that hard water can increase scale buildup

• Completely dry all parts between de-scaling and disinfecting. And after disinfecting, carefully rinse the tank to avoid breathing harmful chemicals.

• Clean it before you store it. And clean it again when you take it out of storage for the heating season.

Controlling humidity

Most humidifiers have a dial or digital humidistat that shuts off the unit when it reaches a preset humidity level. Models without a humidistat can raise the humidity enough to cause condensation on windows. Also, too much humidification can promote growth of mold, bacteria, and dust mites.

Most humidifiers won’t let you set the humidity below 30 percent, a level that can cause window condensation when outside temperatures drop below 20° F. That means you might not be able to use the humidifier when the weather turns very cold.

Related links

Humidifier buying guide 1/11

7 easy ways to reduce indoor air pollution 8/10

Humidifier hints: 5 things to keep in mind before you buy
Copyright © 2003-2012 by Consumers Union of United States., Inc., 101 Truman Avenue, Yonkers, NY 10703, a nonprofit organization. No downloading, transmission, photocopying, or commercial use permitted. Visit www.GreenerChoices.org.