&EPA
United States Air And
Environmental Protection Radiation
Agency (ANR-445)
20A-4001
February 1990
Air Facts No. 7
Residential Air Cleaners
Air Cleaning
Air cleaning is one of three methods of reducing pollutants
in indoor air. In order of effectiveness, the three methods
are: 1) removal of the source or control of its emissions,
2) ventilation, and 3) air cleaning. Air cleaning can be used
as an adjunct to source control and ventilation. However,
air cleaning alone cannot adequately remove all of the
pollutants typically found in indoor air. . .
Should You Use An Air Cleaner?
Many factors need'to be considered in determining
whether use of an air cleaner is appropriate in a'particular '.
setting. Therefore, the decision whether or not to use an air
cleaner is left to the individual. EPA has not taken a
position either for or against the use of these devices in
the home. • .
Will Air Cleaning Reduce Health Effects?
Air cleaners may reduce the health effects from some
particles - small solid or liquid substances suspended in air,
such as dust or light spray mists. .
• Some air cleaners, under the right conditions, can
effectively remove certain respirable-size particles (for
example, tobacco smoke particles). These invisible particles
are of concern because they can be inhaled deeply into the
lungs. Removing such particles may reduce associated
health effects in exposed people: These effects may range
from eye and lung irritation to more serious effects such as
cancer and decreased lung function.
• Some controversy exists about whether air cleaners can
reduce the allergic reactions produced by larger particles
such as pollen, house dust allergens, some molds, and
animal dander. Most of these particles are fo.und where
they settle on surfaces in the home, rather than in the air.
They cannot be removed by an air cleaner unless disturbed
and resuspended in the air.
Air cleaners that do not contain special media, such as
activated Carbon or alumina, will not remove gaseous .
pollutants, including radon, or. reduce their associated
health effects. Whether air cleaners that contain these
media are effective in reducing health risks from gaseous
pollutants cannot be-adequately assessed at this time. In
addition, the effectiveness of air cleaners in. reducing the
health risks from radon progeny (decay products) cannot
be adequately evaluated at present. The removal of gaseous
pollutants and radon and its progeny is not addressed1
further in this fact sheet. Health effects from these
pollutants may be serious, however, and they are of concern
in indoor air. ,,
Types Of Ajr Cleaners
Some air cleaners may be "installed in the ducts which are
part of central heating or air-conditioning systems in
homes. Portable air cleaners stand alone in a room.
Types of air cleaners include:
• Mechanical filters, similar to, and including, the typical
furnace filter.
• Electronic air cleaners (for example, electrostatic •
precipitators) which trap charged particles using an
electrical, field.
* Ion generators which act by charging the particles in a
room. The charged particles are then attracted to walls,
floors, draperies, etc. or a charged collector.
• "Hybrid" devices, which contain two or more of the
particle removal devices discussed above.
Assessing Potential Performance
At a minimum, you should consider the following major
factors affecting the performance of the air cleaner:
• The percentage of the particles removed as they go
through the device (that is, the efficiency).
• The amount of air handled by the device. For example,
an air cleaner may have a high efficiency filter, but it may
process only 10 cubic feet of air each minute. Suppose that
the air cleaner is put in a room of typical size, containing-
1000 cubic feet of air. In this room, it will take a long time
for all.the air to be processed. In some cases, pollutants
may be generated more quickly than they are removed.
• The effective volume of the air to be cleaned. A single ' ;
portable unit used in a room within a large building in
which the air flows between,several apartments or offices
would be of little of no value. '
• The decrease in performance which may occur between
maintenance periods and if periodic maintenance is not
performed on schedule. , •
€Oi 'Printed on Recycled,Paper
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Additional Factors To Consider
• Ion generators and electronic air cleaners may produce
ozone, particularly if they are not properly installed and
maintained. Ozone can be a lung irritant.
• Gases and odors from particles collected by the devices
may be redispersed into the air.
• The odor of tobacco smoke is largely due to gases in the
smoke, rather than particles. Thus, you may smell a
tobacco odor even when the smoke particles have been
removed.
• Some devices scent the air to mask odors, which may
lead you to believe that the odor-causing pollutants have
been removed. , .
• Ion generators, especially those that do not contain a
collector, may cause soiling of walls and,other surfaces.
• You may be bothered by noise from portable air cleaners,
even at low speeds.
• Maintenance costs, such as costs for the replacement of
filters, may be significant. You should consider these costs
in addition to the initial cost of purchase. In general, the
most effective units are also the most costly.
. • i ' ' ,'
Obtaining Adequate Performance
Proper installation, use, and care. Follow the
manufacturer's directions to assure that the air cleaner
works properly. To avoid any electrical or mechanical
hazards, be sure the unit is listed with Underwriters
Laboratories (UL) or another recognized independent safety
testing laboratory.
Perform routine maintenance, as required. Generally
speaking, air cleaners require frequent cleaning and filter
replacement to function properly.
Proper placement. Place portable air cleaners so:
• They are near a specific pollutant source, if one exists.
• They force the cleaned air into occupied areas.
• The inlet and outlet-are not blocked by walls, furniture,
or other obstructions.
For in-duct devices, assure that the inlets and outlets of the
heating or cooling system are not blocked by furniture and
other obstructions.
Comparing Air Cleaners
, - ' ' i' '
One common method of rating high efficiency filters uses a
procedure in Military Standard 282. This procedure
measures how well small peirticles of a specific chemical are
removed by the filter.
The Federal government has not published guidelines or
standards that can be used to determine how .well low to
medium efficiency air cleaners work. However, standards
have been developed by private standard-setting trade
associations. These standards may be useful in comparing
air cleaners.
For further information on standards for in-duct air
cleaners, contact your local heating or air-conditioning
contractor or:
Air-Conditioning and Refrigeration
Institute (ARI)
1501 Wilson Blvd., 6th Floor
Arlington, VA 22209
For further information on standards for portable air
cleaners, send a stamped, self-addressed envelope to:
Association of Home Appliance .
Manufacturers (AHAM) .
Air Cleaner Certification Program
20 North Wacker Drive
Chicago, IL 60606
Additional Information
You can find a more in-depth analysis of air cleaners in the
EPA document. Residential Air-Cleaning. Devices: A Summary
of Available Information. For this document and other EPA
' indoor air publications, contact:
Public Information Center
U.S. Environmental Protection Agency
Mail Code PM-211B
401 M St., SW
Washington, DC 20460
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