Keep it clean: Dirty humidifiers and health problems

Dirty water tanks and filters in humidifiers can grow bacteria and mold. This mainly can cause problems for people with asthma and allergies. But dirty humidifiers can be trouble even for healthy people when they release mist or steam tainted with bacteria or fungi into the air. That may trigger flu-like symptoms or even lung illnesses. Evaporators and steam vaporizers may be less likely to release airborne allergens than may cool-mist humidifiers.