Cleaning a room humidifier

A humidifier eases a dry nose, throat and skin in winter, and cuts down on static, peeling wallpaper and cracked paint and furniture. Its tank of standing water also grows bacteria and mold, and ultrasonic and impeller ("cool mist") models can spray those microorganisms and the minerals in the water into the air. Breathing mist that carries them has been linked to a type of lung inflammation. Children, older adults and people with lung disease or respiratory allergies may be more sensitive. Regular cleaning cuts down how much of that gets into the air.

What you need

• A bottle brush or a scrubber
• A clean, dry towel
• 3 percent hydrogen peroxide, or the cleaner the manual names
• Distilled water
• A hygrometer, to read the room's humidity

Steps

1. 1

   Unplug it

   Unplug the humidifier before you empty, refill or clean it.

   1 min

2. 2

   Empty the tank and wipe it dry every day

   Pour out the old water and wipe every surface dry before you refill. On a console model, change the water the way the manual says.

   3 min

3. 3

   Refill with low-mineral water

   Use bottled water labeled "distilled." Minerals in tap water build up as scale, which is a breeding ground for microorganisms, and ultrasonic and impeller models spray them into the room as white dust. Water labeled "spring," "artesian" or "mineral" hasn't had its minerals removed.

   2 min

4. 4

   Scrub the tank every third day

   Empty the tank and scrub away any scale, deposits or film on the sides and inside surfaces. Use the cleaner or disinfectant the manual names. If it names none, wipe every surface that touches water with 3 percent hydrogen peroxide.

   10 min

5. 5

   Rinse it several times

   After any cleaner or disinfectant, rinse the tank with several changes of tap water so no chemical goes into the air when you run it.

   3 min

6. 6

   Check the room's humidity

   Keep it at 50 percent or lower. Higher humidity encourages dust mites and mold. If water condenses on windows, walls or pictures, move the humidifier, lower its setting or run it less.

   1 min

Which kind you have

• Ultrasonic models make a cool mist with sound vibrations, and impeller models with a fast-spinning disk. These two spread the most microorganisms and minerals.
• Evaporative models blow air through a wet wick, belt or filter. Steam vaporizers, including "warm mist" models, boil the water. Both can grow microorganisms in a standing tank but put fewer of them, and few minerals, into the air.
• Console models sit on the floor, and central humidifiers are built into the furnace. For both, follow the manufacturer's cleaning directions and don't let water stand in a tank for long.

Keep a steam vaporizer out of children's reach, because the steam and boiling water can burn. Don't let the carpet, drapes or tablecloths around a humidifier get damp. If they do, turn the output down or run it on and off.

At the end of the season

Clean the humidifier the way the manual directs, make sure every part is dry and throw away used demineralization cartridges, cassettes or filters. Store it somewhere dry. When you take it out again, clean it once more and dust the outside.

Stop using the humidifier and call your doctor if you have breathing symptoms you think come with using it, even when you've kept it clean.