Michigan State University Extension
Home Maintenance And Repair - 01500032
06/24/03
Air Cleaning, Types of Cleaners
In tighter, more energy-efficient buildings,
pollutants are not as readily removed by natural
ventilation. Filters or electronic air cleaners trap
particulates (tiny particles) from the air flowing through
them and recirculate the cleaned air back to the building
interior.
In Forced-Air Systems:
Cleaners can be installed in central forced-air
heating or cooling systems by heating or air conditioning
contractors. Standard filters, of disposable fiberglass
(commonly used in furnaces) or washable metal mesh cost
the least but are the least efficient, trapping only large
particles.
Media filters contain a medium, such as cellulose,
activated charcoal, etc. which traps smaller particles and
which must be replaced at least annually. A medium such as
charcoal will remove odors from the air.
Electronic air cleaners are by far the most efficient
cleaners of indoor air and the most expensive. They
attract and retain pollutants like a powerful magnet.
Millions of airborne dust, smoke, and pollen particles are
carried through return air ducts to the electronic air
cleaner. When they reach the unit, the larger particles
are trapped by a screen prefilter. Smaller particles pass
through to the ionizing section where they receive an
electrical charge. These charged particles continue
through the cell to the collecting area where they are
attracted to a series of grounded plates. The pollutants
are held in this section until washed away during
cleaning. Electronic air cleaners are 10 to 20 times more
efficient than standard filters.
Portable Air Cleaners:
These also operate with a filter, standard or media
type, or are electronic air cleaners. Some will clean air
in only one room; others are large enough to clean air in
two or more rooms.
An electronic cleaner produces negative ions that are
attracted to the pollutants. All units with claims saying
that they clean the air electronically may not have a
negative-ion generator. Units that have a negative-ion
generator may produce some ozone.
The units operate in one of two ways. In the first
type, negative ions are expelled to room air where the
ions attach themselves to pollutants that become
negatively charged and are attracted to the nearest
positive surface. These deposited pollutants must be
removed from surfaces in the room. In the second type, air
is drawn through a prefilter in the unit that removes
larger particles of pollen and dust and traps some
tobacco smoke and odors. The generator in the unit
produces negative ions that attach to small particles of
dust, smoke and other pollutants as the air passes through
the cleaner. The charged particles are then attracted to a
positively charged plate before the air is returned to the
room. A fan is needed to pull air through the charging
area and to return the cleaned air to the room. The
prefilter and the plate collector must be cleaned
periodically by washing, or be replaced.
Consumers considering the purchase of an air
cleaner/freshener should determine type of air cleaning
needed to provide the desired air quality. If odor and
larger particle removal would result in satisfactory air
quality, the filtering system cleaner may be adequate.
If fine particles that may cause allergic reactions must
be removed an electronic unit may be needed at a higher
price.
Air Cleaners--Cleaning:
For any air filter to work efficiently, it must be
cleaned or replaced from time to time. Dirty filters add
up to more money for the consumer because they force the
heating/cooling system to circulate the air while pulling
it through a clogged and dirty filter.
This article was written by Anne Field, Extension
Specialist, Emeritus, with references from Colorado
Extension newsletter, Service in Action, the Air
Conditioning and Refrigeration Institute, and the American
Household Appliance Manufacturers.
This information is for educational purposes only. References
to commercial products or trade names does not imply
endorsement by MSU Extension or bias against those not
mentioned. This information becomes public property upon
publication and may be printed verbatim with credit to MSU
Extension. Reprinting cannot be used to endorse or advertise
a commercial product or company.
MSU is an affirmative-action, equal-opportunity employer. Michigan State
University Extension programs and materials are open to all without regard to race,
color, national origin, gender, gender identity, religion, age, height, weight, disability,
political beliefs, sexual orientation, marital status, family status or veteran status.
Issued in furtherance of MSU Extension work, acts of May 8 and June 30, 1914, in
cooperation with the U.S. Department of Agriculture. Thomas G. Coon, Director,
MSU Extension, East Lansing,MI 48824. This information is for educational
purposes only. Reference to commercial products or trade names does not imply
endorsement by MSU Extension or bias against those not mentioned.
This file was generated from data base 02 on 02/04/08.
Data base 02 was last revised on 06/24/03.
For more information about this data base or its contents please contact
strausc@msu.edu .