Use and Care of Humidifiers
Introduction
Humidifiers are commonly used in homes to relieve the physical discomforts of dry nose, throat, lips, and skin. The moisture they add to dry air also helps alleviate common nuisances brought on by winter heating, such as static electricity, peeling wallpaper, and cracks in paint and furniture. However, excess moisture can encourage the growth of biological organisms in the home. These organisms include dust mites, which are microscopic animals that produce materials causing allergic reactions to household dust, and molds.
Recent studies by the Environmental Protection Agency (EPA) and the Consumer Product Safety Commission (CPSC) have shown that ultrasonic and impeller (or “cool mist”) humidifiers can disperse materials, such as microorganisms and minerals, from their water tanks into indoor air. At present, only limited information is available on the growth of microorganisms and the dispersal of microorganisms and minerals by home humidifiers. Proper care and cleaning of ultrasonic and impeller humidifiers are important for reducing potential exposures to microorganisms, such as bacteria and molds. Microorganisms often grow in humidifiers that are equipped with tanks containing standing water. Breathing mist containing these pollutants has been implicated as causing a certain type of inflammation of the lungs.
The Federal government has not concluded that the dispersal of minerals by home humidifiers poses a serious health risk. Nevertheless, using water with lower mineral content will reduce exposures to these materials.
The young, the elderly, and those people with lung diseases or respiratory allergies may be particularly susceptible to certain types of airborne pollutants. However, if you follow the recommendations for the use and care of home humidifiers provided in this fact sheet, the potential for dispersal of microorganisms and minerals from your humidifier should be reduced.
Types of Humidifiers and Associated Pollutants
Console humidifiers are encased in cabinets that are designed for floor use. Portable humidifiers are smaller and more readily moved. Central humidifiers are built into heating and air-conditioning systems and humidify the whole house.
The two types of humidifiers which generally appear to produce the greatest dispersions of both microorganisms and minerals are:
1. Ultrasonic, which creates a cool mist by means of ultrasonic sound vibrations.
2. Impeller, or “cool mist,” which produces a cool mist by means of a high speed rotating disk.
Two additional types of humidifiers can allow for growth of micro-organisms if they are equipped with a tank that holds standing water but generally disperse less, if any, of these pollutants into the air. These are:
1. Evaporative, which transmits moisture into the air invisibly by using a fan to blow air through a moistened absorbent material, such as a belt, wick, or filter.
2. Steam vaporizer, which create steam by heating water with an electrical heating element or electrodes. “Warm mist” humidifiers are a type of steam vaporizer humidifier in which the steam is cooled before exiting the machine.
Note: Steam vaporizer and evaporative humidifiers are not expected to disperse substantial amounts of minerals. A steam vaporizer tested by EPA did not disperse measurable amounts of minerals; evaporative humidifiers have not been tested by EPA for mineral dispersal.
Can I Use Tap Water in My Ultrasonic or Impeller Humidifier?
2. Consider using demineralization cartridges, cassettes, or filters if supplied or recommended for use with your humidifier
Be aware, however, that the ability of these devices to remove minerals may vary widely. Further research is needed to determine how well, and how long, these devices work. Watch for the appearance of “white dust,” which would indicate that minerals are not being removed.
Also, in areas of the country where the mineral content in the tap water is high, using distilled water may be less expensive than cartridges, cassettes, or filters.