Cool mist, warm mist, ultrasonic, and evaporative humidifiers
How each type makes moisture, in EPA terms.
Ultrasonic and impeller: cool mist
The EPA describes ultrasonic humidifiers as making "a cool mist by means of ultrasonic sound vibrations." It describes impeller humidifiers as making "a cool mist by means of a high-speed rotating disk."
Steam and warm mist
The EPA says steam vaporizers "create steam by heating water with an electrical heating element or electrodes." It says "warm mist" humidifiers are a type of steam vaporizer in which the steam is cooled before it leaves the machine.
Evaporative
The EPA says evaporative humidifiers "transmit moisture into the air invisibly by using a fan to blow air through a moistened absorbent material, such as a belt, wick, or filter." Check the maker's manual for the part number and how often to replace it.
What the type means for minerals
The EPA says ultrasonic and impeller humidifiers "generally appear to produce the greatest dispersions of both microorganisms and minerals." It says steam vaporizer and evaporative humidifiers "are not expected to disperse substantial amounts of minerals." The EPA also says evaporative and steam types "can allow for growth of microorganisms if they are equipped with a tank that holds standing water." Our cleaning guide covers the EPA care steps.
Hot water and children
The EPA says to "Keep steam vaporizer humidifiers out of the reach of children." It also says: "Steam and boiling water may cause burns." Read the maker's warnings for any heated model.
What we do not do
We do not rank types or name a model as a pick. The right type depends on your room, your water, and how much cleaning you will do.
This is general information, not medical or purchasing advice.
Sources: EPA, Use and Care of Home Humidifiers.
FAQ
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