When your baby 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. A humidifier can also ease itchy skin and other problems associated with dry winter air. 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.  When homing in on humidifiers, here are five questions to keep in mind:

Are you the queen (or king) of clean? Before buying a humidifier, be sure you're willing to take the trouble to clean and disinfect it regularly to prevent growth of bacteria, mold and mildew. Germs thrive wherever there’s standing water. Follow the manufacturer’s cleaning instructions, which should also indicate how frequently to clean your unit. To make cleaning easier, look for easy-to-use controls and for a removable tank that fits beneath faucets. The filter should also be a cinch to replace.

Cool or warm-mist model? Warm-mist humidifiers tend to be quieter than cool-mist models; some make little or no noise except mild boiling and hissing sounds. But if you want to choose this option, and your pediatrician is OK with it, put the humidifier in a spot where your baby or toddler can’t reach or touch it, or accidentally knock it over. The water in it gets hot.

Does it have a humidistat? Whether it's dial or digital, a humidistat controls humidity levels and shuts the humidifier off when the set level is reached. Humidistats that display room humidity levels and settings are best. Models without a humidistat can allow humidity levels to rise too high, which can lead to mold and bacteria growth.

Is it automated? Some humidifiers will turn off by themselves if the water runs dry. That’s a plus--and one less thing to have to remember.

Does your home have hard water? Some humidifiers have lower output with hard water. Fortunately, you can easily remedy that by using distilled water, which has a lower mineral content than most tap water and can help boost your humidifier’s efficiency.

See our report on how to buy a humidifier for more information.