Some with allergies, asthma and other upper respiratory conditions get relief from increased moisture.

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Even a mild winter in can bring cold weather and too much time indoors in dry, heated spaces. For many of us, all that hot air equals stuffed up noses, scratchy throats and parched skin.

Back in the day, Grandma’s remedy was to place pans of water by heating vents or on top of radiators. Now, millions opt for humidifiers to put moisture back into their environments.

According to Consumer Reports, sales of humidifiers typically triple during winter months and there are plenty to choose from — single-room table top units, console or floor models and whole house systems that attach directly to the furnace.

Some provide cool mist, some create warm mist or steam and some offer the option of either. Many use fans to disperse moisture. Ultrasonic models use vibrating nebulizers, evaporative models blow air over a wet wick and impeller models produce mist with a rotating disc.

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Experts say individuals with allergies, asthma and other upper respiratory conditions can get relief from increased moisture in the air.

“When it’s cold out, the air gets drier,” says Seth Brown, a physician who runs The Connecticut Sinus Institute ( “Add to that most heating systems dry out the air in your home and it’s easy to see why some people, especially those with recurrent nose bleeds, colds, coughs, asthma and sinus infections feel better when they use them.”

Glastonbury, Conn., resident Michelle Noehren says since she started using a humidifier in the bedroom at night, her typical winter cough has disappeared. She and husband Dan were so impressed with the humidifier’s effect, they put one in their 8 ½-month-old daughter’s room as well.

“It’s done wonders,” says Noehren. “We don’t cough and the baby hasn’t had any more colds.”

But while moisturized air can help, it can hurt, too. Standing water and mineral buildups inside humidifiers can introduce bacteria and allergy triggers into the air. Unless humidifiers are cleaned regularly, Brown says, they can become extremely efficient mold machines. Run a humidifier for too long and increase the relative humidity to more than 50 percent and mold and mildew can start to build up on damp surfaces throughout the room as well. (Humidity levels of 30 to 50 percent are recommended.)

“Unless you’re very diligent about keeping your unit clean and changing the filters, it does more harm than good,” says Brown. “Bacteria can grow in the tank and then is released into the air.”

Breathing that mist can result in a condition called “humidifier lung.” The problem is so serious that the U.S. Consumer Product Safety Commission issued a safety alert to consumers warning of the dangers.

“Film or scum appearing on the water surface, on the sides or bottom of the tank, or on exposed motor parts may indicate the humidifier tank contains bacteria or fungi. Breathing dirty mist may cause lung problems ranging from flu-like symptoms to serious infection,” the warning states.

The EPA recommends changing the water in a humidifier every day and cleaning humidifier units every third day.

Noehren says she and her husband are conscious of the need for regular maintenance.

“My husband is a germophobe,” says Noehren. “He cleans the units with bleach every other day.”

Some brands advertise antimicrobial coatings, cartridges and other technology to cut down on bacteria growth. Consumer Reports did a review of humidifiers for its January 2011 issue and found that not all units lived up to their claims.

“Low prices and a raft of antimicrobial promises can be extremely enticing, but our latest test shows that some models humidify less than their claims suggest,” said Bob Markovick, home and yard editor at Consumer Reports, when the review was released. “And even with humidifiers that discourage microbes, consumers will still need to clean and disinfect the tanks regularly due to the sitting water.”

Things to keep in mind when shopping for a humidifier include noise levels, since most folks use units at night while they sleep, energy efficiency and whether to opt for cool or warm mist. Brown says that other than keeping steam or warm vapor units out of children’s rooms, it really doesn’t matter.

“It’s the moisture, not the temperature,” says Brown. “It’s just personal preference. If you’re looking to save money, you can bypass the ones with all the bells and whistles and opt for the basic model. They’re just as good.”

And once the heat is off and the weather warms up? Clean the humidifier and put it away until next winter, advises Brown.