The National Conservation GuildThe National Conservation GuildIon generators act by charging the particles in a room so that they are
attracted to walls, floors, tabletops, draperies, occupants, etc. Abrasion
can result in these particles being resuspended into the air. In some cases
these devices contain a collector to attract the charged particles back
to the unit. While ion generators may remove small particles (e.g., those
in tobacco smoke) from the indoor air, they do not remove gases or odors,
and may be relatively ineffective in removing large particles such as pollen
and house dust allergens. Although some have suggested that these devices
provide a benefit by rectifying a hypothesized ion imbalance, no controlled
studies have confirmed this effect.
Ozone, a lung irritant, is produced indirectly by ion generators and some
other electronic air cleaners and directly by ozone generators. While indirect
ozone production is of concem, there is even greater concern with the direct,
and purposeful introduction of a lung irritant into indoor air. There is
no difference, despite some marketers' claims, between ozone in smog outdoors
and ozone produced by these devices. Under certain use conditions ion generators
and other ozone generating air cleaners can produce levels of this lung
irritant significantly above levels thought harmful to human health.
A small percentage of air cleaners that claim a health benefit may be regulated
by FDA as a medical device. The Food and Drug Administration has set a limit
ofo.oS parts per million ofozone for medical devices. Although ozone can
be useful in reducing odors and pollutants in unoccupied spaces (such as
removing smoke odors from homes involved in fires) the levels needed to
achieve this are above those generally thought to be safe for humans.
Ion generators and ozone generators are types of air cleaners; others
include mechanical filter air cleaners, electronic air cleaners (e.g., electrostatic
precipitators), and hybrid air cleaners utilizing two or more techniques.
Generally speaking, existing air cleaners are not appropriate single solutions
to indoor air quality problems, but can be useful as an adjunct to effective
source control and adequate ventilation. Air cleaning alone cannot adequately
remove all pollutants typically found in indoor- air.
The value of any air cleaner depends upon a number of factors, including
its basic efficiency, proper selection for the type of pollutant to be removed,
proper installation in relation to the space, and faithful maintenance.
Drawbacks, varying with type, may include inadequate pollutant removal.
redispersement of pollutants, deceptive masking rather than removal, generation
of ozone, and unacceptable noise levels.
The EPA and CPSC have not taken a position either for or against the use
of these devices in the home.
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