The Use and Care of Home Humidifiers
The following is courtesy of the Environmental Protection
Agency's web site.
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
which 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.
Can I Use Tap Water in My Ultrasonic or Impeller Humidifier?
The Federal government has not concluded that using tap water in
ultrasonic or impeller humidifiers poses a serious health risk.
However, researchers have documented that these humidifiers are
very efficient at dispersing minerals in tap water into the air.
In addition, some consumers are bothered by a "white dust"
that may appear on surfaces during use of these devices. Most importantly,
minerals in tap water may increase the development of crusty deposits,
or scale, in humidifiers. Scale can be a breeding ground for microorganisms.
Retarding the growth of scale is the most compelling reason to
find alternatives to tap water. For this reason, or if white dust
is a problem or you wish to minimize your exposure to minerals in
the tap water as a matter of prudence, you should either:
Use bottled water labeled "distilled." While distilled
water still contains some mineral content, it will likely contain
lower mineral content than most tap water. Distillation is the most
effective method for removing minerals from water.
Two additional demineralization processes, deionization and reverse
osmosis, remove most of the minerals from water, but are generally
less effective than distillation. Water demineralized by these two
processes would, on the average, be expected to contain a higher
mineral content than distilled waters. "Purified" water
may be produced by any of these three or other similar processes.
Be aware, however, that not all bottled water is produced using
demineralization processes. Bottled waters labeled "spring",
"artesian" or "mineral" have not been treated
to remove mineral content.
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.
Types of Humidifiers and Associated Pollutants
Console humidifiers are encased in cabinets which 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:
Ultrasonic, which create a cool mist by means of ultrasonic sound
vibrations.
Impeller, or "cool mist," which produce 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:
Evaporative, which 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.
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.
Recommendations for Use and Care
It is important to use a humidifier only when conditions require
it, to use the correct moisture setting for existing conditions,
and to clean it thoroughly.
The possible health effects resulting from the dispersal of microorganisms
and minerals by home humidifiers are not fully understood. Meanwhile,
it may be prudent to reduce the potential for personal exposures
to these materials by taking the following precautions, particularly
when using ultrasonic and impeller humidifiers.
Empty the tank, wipe all surfaces dry, and refill the water in
portable humidifiers daily to reduce any growth of microorganisms;
follow the manufacturer's instructions for changing water in console
humidifiers. Be sure you unplug the unit from the electrical socket
first.
Use water with low mineral content to prevent the build-up of scale
and the dispersal of minerals into the air. See the box on the left
for information on using water with low mineral content.
Clean portable humidifiers every third day. Empty the tank and use
a brush or other scrubber to clean it. Remove any scale, deposits,
or film that has formed on the sides of the tank or on interior
surfaces, and wipe all surfaces dry. Again, be sure you unplug the
unit.
Follow the manufacturer's suggestions on the use of cleaning products
or disinfectants. In the absence of specific recommendations, clean
all surfaces coming in contact with water with a 3% solution of
hydrogen peroxide. If you use any cleaning or disinfecting agent,
rinse the tank thoroughly with several changes of tap water to prevent
dispersal of chemicals into the air during use.
Follow the manufacturer's directions on cleaning and maintaining
console and central (furnace mounted) humidifiers. In particular,
if the humidifier contains a tank, do not allow water to stand in
the tank for extended periods of time, and keep the water clean.
Keep steam vaporizer humidifiers out of the reach of children. Steam
and boiling water may cause burns.
Do not humidify to indoor relative humidity levels exceeding 50
percent. Higher humidity levels may encourage the growth of biological
organisms in the home. Hygrometers, available at local hardware
stores, may be used to measure humidity levels. Some humidifiers
contain a built-in humidistat which may be adjusted to the proper
moisture level. If water condenses on windows, walls, or pictures,
either relocate the humidifier, lower its humidistat setting, or
reduce its use.
Do not permit the area around the humidifier to become damp or wet.
If dampness occurs, turn the output volume of the humidifier down.
If the humidifier output volume cannot be turned down, use the,
humidifier intermittently. Do not allow absorbent materials, such
as carpeting, drapes, or table cloths, to become damp.
Follow the manufacturer's instructions regarding the use, maintenance,
and replacement of any materials supplied with the humidifier. Use
appropriate materials as recommended by the product manufacturer.
Clean the humidifier, as directed, at the end of the humidifying
season or when the product will not be in frequent use. Before storage,
make sure all the parts are dry. Dispose of all used demineralization
cartridges, cassettes, or filters. Store the unit in a dry location.
After storage, clean the unit again and remove any dust on the outside.
Stop using your humidifier and contact your physician if you have
respiratory symptoms which you believe are associated with periods
of use of your home humidifier, even if you are following maintenance
directions.
Additional Sources of Information
For additional EPA publications on indoor air quality, contact:
IAQ Information Clearinghouse [IAQ INFO] (sponsored by the U.S.
EPA)
PO Box 37133
Washington D.C. 20013-7133
(703) 356-4020 or 800-438-4318
fax: (703) 356-5386 or e-mail: iaqinfo@aol.com
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