Air Purifiers and Ozone

Is too much ozone harmful to health?

Air purifiers like the Oreck XL Tabletop Professional (*Est. $360) and the Friedrich C-90B (*Est. $450) are electrostatic air cleaners (though they also include other air-filtering technologies like filters and a fan). This means that they use an electrical charge. A byproduct of this technology is ozone gas. In sufficient quantities, ozone can be toxic; in smaller amounts, it can affect those with asthma or other respiratory problems.

Although some reviews say that the ozone produced by electrostatic air cleaners is safe for those in normal good health, both the U.S. Environmental Protection Agency and American Lung Association (ALA) advise against using these devices, since there are many ozone-free HEPA models on the market. While there are no government guidelines for ozone levels in the home, the Food and Drug Administration does regulate ozone for medical devices (the FDA does not recognize home air cleaners as medical devices) and air purifier manufacturers may voluntarily submit their air cleaners for ozone-emission testing. The FDA mandates a limit of 50 parts per billion (ppb) when measured at two inches from the unit.

The jury is still out on whether small amounts of ozone are harmful to healthy individuals. There have been a lot of studies on the health effects of outdoor ozone levels, but few long-term tests have measured the effects of ozone produced by indoor devices like air cleaners. One 2006 study published in the Journal of the Air & Waste Management Association tested 13 air purifiers, including several personal air cleaners designed to be in close proximity to a person. Research analysts conclude that even these are capable of producing steady levels of indoor ozone that exceed health standards. Indeed, some people say they can smell ozone and some report headaches. Some reviewers, including Consumer Reports, say you should avoid air cleaners that produce ozone that exceed FDA guidelines, while other organizations say you should avoid home air purifiers that produce any amount of ozone at all. While reviews say the Friedrich C-90B does a good job removing allergens from the air, it does produce small amounts of ozone as a byproduct.

Beginning this year, California has placed a ban on any air purifier that produces ozone levels greater than 50 ppb; the state's Air Resources Board is giving manufacturers until October 2010 to have their air purifiers tested, certified and labeled as emitting safe levels of ozone or pull them from the shelves. For now this regulation will mostly affect air purifiers which are strictly ozone generators rather than electrostatic precipitators such as the Oreck XL. The California Air Resources Board has decided that further testing is needed to determine if the ozone levels now considered to be safe should be lowered even further.