Keep it clean: Dirty humidifiers and health problems

Dirty reservoirs and filters in humidifiers can quickly breed bacteria and mold. Dirty humidifiers can especially cause problems for people with asthma and allergies. But even in healthy people, dirty humidifiers have the potential to trigger flu-like symptoms or even lung infections when the contaminated mist or steam is released into the air. Evaporators and steam vaporizers may be less likely to release airborne allergens than may cool-mist humidifiers.