Baby Humidifier Safety: Cool Mist, Placement, Cleaning and Water

The rules at a glance

From CHOP, MedlinePlus and EPA.

Rule	Why	Source
Cool mist only	Vaporizers can burn a child who gets close or knocks one over	CHOP, citing the AAP; MedlinePlus
About 3 feet from the child and crib	Keeps mist off bedding and the unit out of reach	CHOP; MedlinePlus says several feet
Empty and refill daily	Bacteria grow in standing water	EPA; MedlinePlus
Clean every 2 to 3 days	Prevents mold and bacteria	CHOP; EPA says every third day
Distilled or filtered water	Limits minerals and microorganism growth	CHOP; EPA recommends distilled
40 to 50% humidity	Too much moisture leads to mold and mildew	MedlinePlus; EPA says not above 50%
Size it to the room	An oversized unit causes condensation that fosters bacteria and mold	CHOP
Automatic shut-off	Stops it running dry	CHOP

Why cool mist

CHOP explains that humidifiers release a mist made from cool water while vaporizers boil water and release steam, and that vaporizers can burn a child who gets too close or knocks over a unit full of hot water. EPA's humidifier guidance says steam and boiling water may cause burns and steam vaporizers should be kept out of reach of children. A cool mist humidifier, whether ultrasonic or evaporative, removes that hazard. If you own a warm-and-cool model, use only the cool setting in a child's room. See cool mist vs warm mist.

Where to put it

• At least 3 feet from the child and the bed or crib, as CHOP suggests; MedlinePlus says several feet.
• On a stable, flat surface where it cannot be pulled down by a cord or reached from the crib.
• With the mist directed into open air, not at the crib, curtains or walls.
• Away from the air quality monitor, if you use one, so it reads the room rather than the mist.

Cleaning

EPA's routine is to empty, wipe dry and refill portable humidifiers daily and clean them every third day, following the maker's directions, using 3% hydrogen peroxide when the manual gives none. CHOP suggests cleaning every 2 to 3 days and before storage, soaking the tank and parts that touch water in a 10% bleach solution (1 part bleach to 9 parts water), emptying and drying the tank whenever you turn it off, and refilling with fresh water daily. Rinse thoroughly after any cleaner and never mix products. See humidifier mold prevention.

Water

EPA recommends water labeled distilled. MedlinePlus says minerals from tap water can be released into the air as white dust that can affect breathing. CHOP suggests filtered or distilled water to limit mineral buildup and microorganism growth. Evaporative humidifiers keep minerals in the wick, so they are more forgiving of tap water, but distilled water still reduces scale. See distilled vs tap water.

Getting the humidity right

MedlinePlus suggests about 40 to 50%. EPA says not to humidify above 50%, and its mold guide recommends 30 to 50% indoors. MedlinePlus warns that running a humidifier too long can leave surfaces constantly damp, leading to mold and mildew. A humidifier with a humidistat helps; otherwise use a hygrometer or a monitor. See air quality monitors for a nursery.

Things to avoid

• Steam vaporizers and warm mist in a child's room.
• Adding anything to the water unless the manual calls for it. AIRCARE's manual, for example, says to use only cleaners and additives recommended for humidifiers.
• Running it all day and night with the door shut without checking humidity.
• Leaving water in the tank between uses.
• A unit too big for the room, which CHOP says can cause condensation.

Good choices for a nursery

From each maker's page or manual.

Humidifier	Type	Tank	Why it suits a nursery
Honeywell HCM-350	Cool, evaporative	1.1 gal	No white dust; dishwasher-safe tank; runs up to 24 h on low
Pure Enrichment MistAire	Cool, ultrasonic	1.7 L	Quiet; optional night light; auto shut-off; up to 250 sq ft
Levoit Classic 200	Cool, ultrasonic	4 L	30 dB; up to 40 h; needs distilled water

Do babies need a humidifier?

Not always. If the nursery already sits at 30 to 50%, a humidifier adds nothing. MedlinePlus says humidifiers can help relieve a stuffy nose and loosen mucus, but a humidifier is not a treatment; for a sick infant, follow your pediatrician's advice. Safe sleep basics from the AAP, such as avoiding overheating and keeping the home smoke-free, matter more. For purifiers, see the best air purifiers for a nursery, and for all humidifier picks, the best humidifiers.