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Air Purifier
Can Dirty Air
Ionic purifiers will now be regulated in California to protect the
public from dangerous ozone emitting products created for profits. These
devices are slowly losing their creditability as having any value
whatsoever.
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In Presence Of Fragrant Cleaning Products, Air Purifiers That Emit Ozone Can Dirty The Air
24 February 2007 - UC Irvine - sciencedaily.com
Science Daily — Indoor air purifiers that produce even
small quantities of ozone may actually make the air dirtier when used
at the same time as household cleaning products, scientists at UC
Irvine have discovered.
Ozone emitted by purifiers
reacts in the air with unsaturated volatile organic compounds such as
limonene – a chemical added to cleaning supplies that gives them a
lemon fragrance – to create additional microscopic particles,
scientists found. Certain ionic purifiers emit ozone as a byproduct of
ionization used for charging airborne particles and electrostatically
attracting them to metal electrodes. Ozonolysis purifiers emit ozone
at higher levels on purpose with the ostensible goal of oxidizing
volatile organic compounds in the air.
This research appeared online this morning in Environmental Science
and Technology. “The public needs to be aware that every air
purification approach has its limitation, and ionization air purifiers
are no exception,” said Sergey Nizkorodov, assistant professor of
chemistry at UCI and co-author of the study. “These air purifiers can
not only elevate the level of ozone, a formidable air pollutant in
itself, but also increase the amount of harmful particulate matter in
indoor air.”
High levels of airborne particles can aggravate asthma and
cardiovascular problems, and have been linked to higher death and lung
cancer rates. Excess ozone can damage the lungs, causing chest pain,
coughing, shortness of breath and throat irritation. Nizkorodov and
students Ahmad Alshawa and Ashley Russell conducted their experiment
in a sparsely furnished office with a floor area of about 11 square
meters. They placed an ozone-emitting air purifier in the middle of
the room along with a large fan to better mix the air. At timed
intervals, limonene vapor was injected in the room. Samples of the air
were taken about one meter from the purifier and analyzed for ozone
and particulate matter levels.
The researchers tested two types of air purifiers – a commercial ionic
purifier that emits about 2 milligrams of ozone per hour, and an
ozonolysis purifier that emits approximately 100 milligrams of ozone
per hour.
Continuous operation of the ionic purifier without limonene resulted
in a slight reduction in the average particle concentration, while
operation of the ozonolysis purifier resulted in no detectable effect
on the particle level. When limonene was added to the room, the
particle concentration shot up in both cases, on some occasions up to
100 times the original level. Adding limonene to the room when a
purifier was not operating produced little change in the overall
particle level.
The scientists also developed a mathematical model that precisely
matched their experimental observations. This model can be used to
predict whether a given air purifier will make the air dirtier in a
given indoor environment.
Scientific data on indoor air purifiers will be important as officials
begin the process of regulating air purifiers that emit ozone. In
September 2006, California Gov. Arnold Schwarzenegger signed into law
Assembly Bill 2276, requiring the California Air Resources Board to
develop regulations that will set emission standards and procedures
for certifying and labeling the devices. “State regulators should set a
strict limit on the amount of ozone produced by air purifiers to
protect the public from exposure to unhealthy ozone and particulate
matter levels,” Nizkorodov said.
The National Science Foundation funded this study. |
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The
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Labors in the Spirits of
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Living on the Lost Planet 
