The U.S. Consumer Product Safety Commission (CPSC) is alerting consumers to possible health hazards resulting from dirty room humidifiers. The CPSC has found that bacteria and fungi often grow in the tanks of portable and console room humidifiers and can be released in the mist. Breathing dirty mist may cause lung problems ranging from flu-like symptoms to serious infection. This information is of special concern to allergy or asthma sufferers whose symptoms may be increased.
Film or scum appearing on the water surface, on the sides or bottom of the tank, or on exposed motor parts may indicate that the humidifier tank contains bacteria or fungi. A crusty deposit or scale may also form within the tank or on parts in the water. This scale is composed of minerals that have settled out of the water creating a surface on which bacteria or fungi may grow.
Minerals can also be released in the mist and settle as fine white dust. This white dust may contain particles that are small enough to enter the lungs. The health effects from inhaling this humidifier dust are not clear, any impact on human health will depend upon the types and amounts of minerals found in the water used.
To reduce the possibility of health hazards from dirty room humidifiers, the staff of the Consumer Product Safety Commission recommends that you take the following precautions:
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.