PART I GENERAL DESCRIPTION ON AIR CLEANING
Fig. 1.2-4 Ozone Molecules converted from oxygen (left)
as a result of an electrical charge, such as that provided by
lightning or UV lights .
Unlike electronic cell, the ion generators don't remove the particulate matter, they only cause them to accumulate and
attach themselves to various surfaces around the room. This means that ion generators only have a temporary effect
of eliminating particles from the air. Once the particles lose the charge, they become airborne again. Those charged
particles are more easily trapped in the human respiratory system. Ion generators can produce ozone, either as a by-
product of use or intentionally.
Some air purifiers use negative ion generators, which are installed at the air outlet to fresh the purified air. Negative
ion has proven to be successful in reducing the overproduction of serotonin, and therefore successful in alleviating
depression in some cases.
Electret media filter-synthetic (Hybrid Filters)
Electret media filter is a hybrid of a mechanical filter and electrostatic filter
or an ion generator in an integrated single filter. The media filter made from
synthetic fibers is inherently negatively charged in the manufacturing
process and retains a charge which attracts airborne particles that are
trapped and retained within the fibers in the conventional methods of
impingement. In some cases, ionizers are used to increase the efficiency of
the trapped media. These filters obtain a moderate efficiency on smaller
particles than the electronic cell. Electret media filters must be changed or
cleaned regularly to maintain system efficiency, as the fibers loose their
electrostatic charge as they become soiled.
Negative ion-negative ion generator
Negative ions are negatively-charged electrical particles that are
magnetically attracted to allergens and other airborne contaminates, which
are positively-charged. The newly-formed larger particles are than able to
fall harmlessly to the ground, and out of the air we breathe.
Fig.
1.2-3 The electret media
filter, also called as hybrid filter,
or synthetic filter.
Oxygen
molecules
Ozone
molecules
Ozone-ozone generator
Ozone is a molecule with three atoms of oxygen, either
directly or as a by product of ionization and electrical
precipitation. High voltage causes the oxygen molecules in
the air to create ozone (O
3
). Ozone does not trap particles,
but can remove odors in the air. Manufacturers of air
cleaner systems that produce ozone may refer to the ozone
as "Supercharged Oxygen", "Activated Oxygen" or
"Enhanced Oxygen" Ozone molecules are converted from
oxygen molecules. The ozone molecule (O
3
) is highly
reactive, so whenever it encounters a floating particulate,
one of the oxygen atoms breaks away to oxidize the
pollutant. This leaves behind O
2
(pure oxygen), refreshing
the air even more. Ozone generators do not utilize filters.
These machines operate by introducing the highly reactive
molecule, Ozone (O
3)
into the air.
1-4
ENGLISH
This process dissipates air borne pollutants comparably the way that bleaching agents are used to sterilize water.
However, ozone is of concern when considering spaces for human occupancy. The high concentration levels required
for contaminant control are in conflict with potential health effects as established by authorities including the National
Institute of Occupational Safety and Health (NIOSH), and the U.S. Food and Drug Administration (FDA). The problem
is that there is much controversy surrounding the use of these machines as "air cleaners". Ozone is considered a
hazardous workplace chemical by O.S.H.A. (U.S. Occupational Safety and Health Administration), and is also
considered an air pollutant that requires regulation by the E.P.A. (Environmental Protection Agency. Ozone may also
be particularly harmful to people with asthma.
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