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Most people are now aware that indoor air pollution is an
issue of growing concern and increased visibility.
Many companies are marketing products and services intended
to improve the quality of your indoor air. You have probably
seen an advertisement, received a coupon in the mail, or been
approached directly by a company offering to clean your air
ducts as a means of improving your home's indoor air quality.
These services typically -- but not always -- range in cost
from $450 to $1,000 per heating and cooling system, depending
on the services offered, the size of the system to be cleaned,
system accessibility, climatic region, and level of contamination.
EPA does not recommend that air ducts be cleaned except
on an as-needed basis because of the continuing uncertainty
about the benefits of duct cleaning under most circumstances.
Duct cleaning generally refers to the cleaning of various
heating and cooling system components of forced air systems,
including the supply and return air ducts and registers, grilles
and diffusers, heat exchangers heating and cooling coils,
condensate drain pans (drip pans), fan motor and fan housing,
and the air handling unit housing (See diagram). (graphics
are missing on EPA sites, check and download later)
If not properly installed, maintained, and operated, these
components may become contaminated with particles of dust,
pollen or other debris. If moisture is present, the potential
for microbiological growth (e.g., mold) is increased and spores
from such growth may be released into the home's living space.
Some of these contaminants may cause allergic reactions or
other symptoms in people if they are exposed to them. If you
decide to have your heating and cooling system cleaned, it
is important to make sure the service provider agrees to clean
all components of the system and is qualified to do so. Failure
to clean a component of a contaminated system can result in
re-contamination of the entire system, thus negating any potential
benefits. Methods of duct cleaning vary, although standards
have been established by industry associations concerned with
air duct cleaning. Typically, a service provider will use
specialized tools to dislodge dirt and other debris in ducts,
then vacuum them out with a high-powered vacuum cleaner.
In addition, the service provider may propose applying chemical
biocides, designed to kill microbiological contaminants, to
the inside of the duct work and to other system components.
Some service providers may also suggest applying chemical
treatments (sealants or other encapsulants) to seal or cover
the inside surfaces of the air ducts and equipment housings
because they believe the sealant will control mold growth
or prevent the release of dirt particles or fibers from ducts.
These practices have yet to be fully researched and you
should be fully informed before deciding to permit the use
of biocides or sealants in your air ducts. They should
only be applied, if at all, after the system has been properly
cleaned of all visible dust or debris.
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