Dirty Humidifiers Can Cause Health Problems

Jason Yost • November 29, 2022

Can Dirty Humidifiers Cause Health Problems?

The United States Consumer Product Safety Commission (CPSC) has found that bacteria and fungi often grow in tanks of portable and console room humidifiers; furthermore, these microorganisms can be released in the mist emitted from the humidifier.

Mineral build-up can also be a problem. Fine minerals can be emitted in the mist, small enough to enter the lungs. The health effects from inhaling these minerals are not clear, any impact on human health will depend upon the types and amounts of minerals found in the water used.

Breathing these contaminants can lead to various lung problems, from flu-like symptoms to serious infections. Those at greatest risk of illness are older adults, children, smokers, and individuals who are immunocompromised (e.g., cancer, diabetes, AIDS) or immune-suppressed (e.g., those going through medical treatments like chemotherapy).

Several things to look for include:

Film or scum anywhere in the humidifier and on its water;
Crusty deposits or scale are minerals that have settled from the water and can house bacteria and fungi; and,
White dust can be a sign of mineral accumulation.

To reduce your exposure to possible contamination you can:

Do not allow film and scale to develop in your humidifier. If possible, change the water in your room humidifier daily. Empty the tank before you fill it. If the tank is not removable, clean it often according to manufacturer's instructions.
Use distilled or demineralized water in your room humidifier to reduce the buildup of scale and the release of dust. Do not use tap water because it contains more minerals. Use demineralization cartridges or filters if supplied or recommended for use with your humidifier.
Drain and clean the tank of your room humidifier before you store it. Clean it after summer storage. Remove dust on the outside of your unit.
Clean your room humidifier well and often during the heating season. Be sure to unplug the humidifier before cleaning. Follow the manufacturer's suggested cleaning methods. If chlorine bleach or other cleaning product or disinfectant is used, make sure to rinse the tank well to avoid breathing harmful chemicals. Use a brush or other scrubber to clean the tank. Be careful not to damage the motor or to scratch the inner surface. Clean or replace sponge filters or belts when needed.
Maintain the relative humidity in your home between 30% and 50% if possible. Humidity levels above 60% may allow moisture to build up indoors and condense on surfaces, where bacteria and fungi can settle and grow. You can measure humidity with an instrument called a hygrometer, available at your local hardware store.