Ozone Air Purifiers Can Dirty Air

Ozone Air Purifiers Can Dirty Air



Feb 2007 - New research 
finds that using indoor air purifiers that produce ozone may 
actually make the air dirtier when they are used at the same 
time as household cleaning products. 
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. This 
creates additional microscopic particles, according to 
scientists at the University of California at Irvine. 
"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." 
The study appeared online Thursday in "Environmental Science 
and Technology." 
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. 
The researchers tested two types of air purifiers - a 
commercial ionic purifier that emits about two milligrams of 
ozone per hour, and an ozonolysis purifier that emits 
approximately 100 milligrams of ozone per hour. 
They found that 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 and can be 
used to predict whether a given air purifier will make the air 
dirtier in a given indoor environment. 
This model could prove important for California state 
officials, who have been tasked with implementing statewide 
emissions standards and labels for indoor air purifiers that 
emit ozone. 
"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.

---