California regulates “ozone generator” air purifiers

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. Manufacturers of ozone generators tout a variety of health benefits. However, 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.

(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 Perratore

Comments

[Jay Ingalls]

I was working for a mass production mfgr of automotive and appliance parts about 1963. A person brought in what may have been the first "electronic air filter", a box about 12 inches high, 8 inches wide, and 8 inches deep. The inventor was promoting it as a great air cleaner, and apparently said it would help people with allergies. One of our engineers knew I had severe allergy problems and aasked me if I wanted to try it for the week end. I did try it, it produced a tremendous amount of ozone, and made my allergies much worse. We decided not to manufacture it.

Knowing what I know now, a control allowing the user to drop the voltage would have allowed the user to reduce the amount of ozone generated, and might have made it useful.

I have installed or had installed paper HEPA filters in our last two houses, and they do reduce the amount of dust in the house and do reduce allergy problems.