For their safety, always use cool-mist humidifiers for children. Hot water or steam from a warm-mist humidifier or steam vaporizer can burn a child if he or she gets too close. In the event of a spill, hot water might also burn.
Humidifiers add moisture to the air. Cool-mist humidifiers may help ease coughing and congestion due to a cold. But more research is needed. Some research has found that heated humidifiers haven't helped cold symptoms.
Warm-mist and cool-mist humidifiers are equally effective in humidifying the air. By the time the water vapor reaches your child's lower airways, it's the same temperature regardless of whether it started out warm or cool.
If you use a humidifier, be sure to keep it clean to prevent mineral buildup and the growth of bacteria and molds. Humidifiers that hold standing water, particularly cool-mist humidifiers, can disperse these materials into the air. Warm-mist humidifiers generally disperse less, if any, of these materials into the air.
Emptying the tank and drying all surfaces of the humidifier daily is one way to safely keep it clean. Also, consider refilling the tank with bottled water that is labeled "distilled" or "purified," both of which contain lower mineral content than most tap water.