In a step that surpasses federal and other state efforts to regulate the emissions from air purifiers, the California Air Resources Board has moved to ban the sale of some ozone generator air purifiers and could even affect some air purifiers that generate ozone as a by-product. In late September, CARB deemed “hazardous” hundreds of different models of ozone generator and air purifier that emit ozone in amounts greater than 50 parts per billion (ppb) in tests and approved a regulation to limit the amount of ozone air purifiers can produce to be certified for open sale in the state. Manufacturers will have 24 months from when the ruling takes effect (the projected date is next April) to get their air purifiers tested by a nationally recognized testing laboratory and certified by CARB. Beyond that 24-month period, any model that that exceeds the 50-ppb threshold must be labeled as appropriate only for industrial use and have a warning about its ozone emissions; electronic models for residential, commercial, in-vehicle, and personal use are affected.

CARB also plans to embark on a public-education campaign to discourage state residents from buying ozone generators even before the 24-month period has elapsed. The California regulation particularly targets what are commonly called ozone generators, which by design produce large amounts of ozone. whirlpool true hepa air purifierManufacturers of ozone generators tout a variety of health benefits. ionic pro air purifier turbo maxHowever, the federal EPA has cautioned generally that any ozone produced would have to greatly exceed public-health standards to be effective at removing most indoor-air contaminants and irritants, including germs, smoke, dust, and odors. air duct cleaning woodlands texas(The best-selling air purifiers in the U.S. market are known as electrostatic precipitators.

Sold by Oreck, The Sharper Image, and others, they use a technology that typically produces less than 50 ppb of ozone as a by-product; these will also have to undergo testing. Another type, filter-based models, produces no ozone.) Even relatively low levels of ground-level ozone, the chief ingredient of smog, have been linked to decreases in lung function and increased risks of throat irritation, coughing, chest pain, and lung-tissue inflammation. For outdoor air, the federal standard is a maximum eight-hour average concentration of 80 ppb; California’s standard is 70 ppb, near the level the U.S. EPA has recently proposed. While no formal standard for indoor air exists, the U.S. Food and Drug Administration imposes a 50-ppb limit on medical devices. But air purifiers don’t fit into this classification. The regulation, according to CARB, could prevent exposure to potentially harmful levels of ozone for an estimated 828,000 Californians. CARB has generated a list of potentially hazardous ozone generators, which includes products designed for use in single rooms, whole houses, cars, entire floors of commercial spaces, and even “personal air purifiers” worn around the neck.

Note that CARB will periodically update the list, and that a product’s nonappearance on the list doesn’t mean it is necessarily safe. No whole-house products that attach to forced-air HVAC systems, for example, are so far on the list. Eliminating allergens and ventilating spaces are more effective than any air purifier, say experts at the U.S. Environmental Protection Agency and the American Lung Association. If you’re considering buying an air purifier, read our latest report, “Filtering the claims,” from the December 2007 of Consumer Reports .—Ed PerratoreYou can create dangerous smog levels in your own home with an ozone-generating air purifier. The finding comes from a study of ozone-emitting air purifiers by Sergey A. Nizkorodov, PhD, and colleagues at the University of California, Irvine. The researchers studied 13 air purifiers known to give off small and large amounts of ozone, a major ingredient in air pollution. Included in the study were several ionic air purifiers made by The Sharper Image, including the popular Ionic Breeze Quadra.

These machines produce detectable levels of ozone. But they did not emit dangerous levels of ozone, except when a Quadra model intended for a large room was tested in a tiny bathroom. Ozone generators, however, were a different story. As they are designed to do, they put a lot of ozone into indoor spaces. The devices quickly caused ozone buildups to levels that would trigger severe smog alerts for outdoor air. "If I put one in my office, I can generate a stage 2 ozone level if I want to," Nizkorodov tells WebMD. "This is the problem -- right now it is not controlled. Air purifiers that make ozone above a certain rate should be banned. The public should not be allowed to buy them." Ozone is great in the upper atmosphere, where it protects the Earth from harmful radiation. According to the American Lung Association, ozone exposure may lead to premature death, shortness of breath, chest pain when inhaling deeply, and wheezing and coughing. High ozone levels irritate the lung and make asthma worse.

The Nizkorodov study, funded by the National Science Foundation, appears in the May issue of theJournal of the Air & Waste Management Association. Ozone Generators vs. Ionic Air Purifiers It's easy for consumers to be confused. Three basic kinds of devices call themselves air purifiers. Consumer Reports has found that "even the best air cleaners could be a frivolous investment." There's no ozone emission from air purifiers that use only high-efficiency particulate air filters (HEPA filters) to cleanse the air. Ionizing air purifiers, because of their electric charge, do create ozone. Consumer Reports has warned that they may give off potentially harmful ozone levels. "There are plenty of ionic air purifiers; only a small fraction make ozone," Nizkorodov says. Mark Connelly, senior director of appliances and home improvement for Consumer Reports, oversees the magazine's air-cleaner tests. "You don't want to say that anything that generates ozone is bad," Connelly tells WebMD. "A printer produces ozone, but just because printers sit on people's desks doesn't mean they should be taken off the market.

But the people who buy air purifiers are most susceptible to the problems they create. You buy it to make things better, and it ends up making things worse for you." Whatever ozone comes from ionic air purifiers pales in comparison to the amount produced by ozone-generating air purifiers. These machines make ozone for one reason: That's what they are designed to do. "Ozone is a very effective way of disinfecting water -- and some believe it is also possible to do this in the air," Nizkorodov says. "Unfortunately, at the concentrations you need to destroy germs and pollutants, the ozone levels are so high you cannot safely use it." In a small bathroom, the UCI researchers found that one ozone generator, the EZ-COM Air Purifier, took only a half hour to build up ozone to a smog level that would force school closings if detected in a city's air. In a 1,250-square-foot office, the device took about a half hour to build ozone to smog levels that would trigger unsafe air alerts. By contrast, the Sharper Image Ionic Breeze Quadra model -- an ionic air purifier, not an ozone generator -- built ozone to a maximum level of 40 parts per billion (ppb) in a large office.

The FDA considers medical devices safe if they emit less than 50 ppb of ozone. The World Health Organization considers eight-hour ozone levels of 60 ppb to be acceptable. The Quadra did make the air unsafe when used in a small bathroom -- not the products' intended use, says Sharper Image spokeswoman Suzie Stephens. "Sharper Image products were included in the study and, in fact, met all safety standards for ultra-low trace ozone emissions when the appropriate-sized models were used in the manufacturer-recommended room sizes," Stephens tells WebMD. "Why they chose to place the unit in a room size for which it is clearly not intended nor used is inexplicable." Stephens worries that the UCI study sows confusion by testing ionic air purifiers alongside ozone generators. Indeed, she points to news reports on the study that confused Sharper Image products with ozone generators. "The study found that ozone generators, not ionic air purifiers when used appropriately, can generate potentially unsafe levels of ozone indoors," Stephens says.

"None of the Sharper Image air purifiers are ozone generators." Government Action on the Way? While Consumer Reports has been critical of ionic air purifiers -- including explicit criticism of the Sharper Image Ionic Breeze Professional with OzoneGuard -- it is far less worried about these devices than about ozone generators. "We slammed ozone generators back in 1992 -- but they are still being marketed to unsuspecting people," he says. "Those people most susceptible to harm are cranking ozone into their lungs. Ozone generators should be regulated first and foremost." There's already a bill before the California legislature to regulate these devices. And the California Air Resources Board will meet on May 25 to update its recommendation on ozone generators. Nizkorodov says he thinks California will set a limit on how much ozone a device will be allowed to generate. He guesses the limit will be between 10 and 100 milligrams of ozone per hour -- and his bet is on the lower limit. His study found that the Sharper Image Ionic Breeze Quadra puts out 2.2 milligrams of ozone per hour -- far below the lowest limit California is likely to set.