11 May 2006
Health Benefits Of Air Purifiers Questioned
Researchers at the University of California (UCI), Irvine, say that indoor air purifiers that produce even a few milligrams of ozone per hour can create an ozone level that exceeds public health standards. "These results mean that people operating air purifiers indoors are more prone to being exposed to ozone levels in excess of public health standards," said chemist Sergey A. Nizkorodov, at UCI.
Nizkorodov's research appears in the Journal of the Air & Waste Management Association. He and his co-researchers hope that their findings will be studied by officials deciding how to regulate the distribution of indoor air purifiers. Although California lawmakers are considering legislation that would require regulations to reduce emissions from indoor air cleaners by 2008, the devices remain on the market because no agency has the outright authority to regulate how much ozone they produce.
Air purifiers target dust, pollen, airborne particles and volatile organic compounds, which are emitted by a wide range of products, including paint, cleaning supplies and pesticides. They are advertised as safe household products for health-conscious people - especially those who suffer from allergies and asthma - but some purifiers produce ozone during operation. These purifiers, which work by charging airborne particles and electrostatically attracting them to metal electrodes, emit ozone as a byproduct of this ionization. The emitted ozone can damage the lungs, causing chest pain, coughing, shortness of breath and throat irritation. It can also worsen chronic respiratory diseases such as asthma and compromise the ability of the body to fight respiratory infections.
For their study, the research group tested several types of air purifiers in various indoor environments, including offices, bathrooms, bedrooms and cars. In many cases, the indoor ozone levels recorded far exceeded outdoor safety guidelines. In some instances, the ozone level reached higher than 350 parts per billion - more than enough to trigger a Stage 2 smog alert if similar levels were detected outside.
Nizkorodov said that the largest increase in ozone levels occurred in small rooms with little ventilation, especially those containing materials that react slowly with ozone such as glossy ceramic tile, PVC tile and plastic. Ozone reacts quicker with materials such as carpet, cloth, rubber and certain metals, destroying itself in the process.
Source: University of California, Irvine