New concerns about ionizing air cleaners
Buying an air cleaner that doesn't clean the air is bad enough. Some of the least effective ionizer models also can expose you to potentially harmful ozone levels, especially if you're among the roughly 80 percent of buyers with asthma or allergy concerns.
Also known as electrostatic precipitators, the five ionizing air cleaners we focused on for this report are supposed to trap charged particles on oppositely charged plates. But as we reported in our October 2003 report on air cleaners, models like Sharper Image's Ionic Breeze, the market leader, did a poor job removing dust and smoke from the air. Our latest tests also show that some ionizing models can expose you to significant amounts of ozone.
Unlike ozone in the upper atmosphere, which helps shield us from harmful ultraviolet rays, ozone near ground level is an irritant that can aggravate asthma and decrease lung function. Air cleaners need not meet ozone limits--not for the federal Environmental Protection Agency, which regulates only outdoor air, nor for the Food and Drug Administration, since it doesn't consider them medical devices, despite the health benefits that some ads imply. (See Air cleaners: The truth behind the accolades.) Manufacturers often submit air cleaners to a voluntary standard that includes a test to see whether they produce more than 50 parts per billion (ppb) of ozone, the same limit the FDA uses for medical devices.
We replicated that test using the sealed polyethylene room specified by Underwriters Laboratories Standard 867 to help ensure consistent results. Ozone levels were measured 2 inches from each machine's air discharge in accordance with the standard. All five ionizers failed the test by producing more than the 50-ppb limit--in some cases, much more.
People don't live in sealed plastic rooms, however. So we also tested these ionizing air cleaners in an open, well-ventilated lab. For comparison, we also tested a top-performing Friedrich electrostatic-precipitator and a Whirlpool HEPA model from previous reports.
We measured ozone levels 2 inches from the machines, as in the sealed-room test, and 3 feet away, since ozone becomes diluted and dissipates rapidly indoors as it reacts with carpet, upholstery, and other surfaces. In our lab tests, two ionizing models--the IonizAir P4620 and the Surround Air XJ-2000--emitted more than 150 and 300 ppb, respectively, 2 inches from the machine.
While few people are likely to sit 2 inches from the air discharge, where our ozone readings were highest, you could be exposed to higher levels than those we measured at 3 feet if you take a cue from manufacturers. The IonizAir's box shows it on a desk near a keyboard and on a nightstand near a sleeping woman. The Ionic Pro CL-369 is shown next to a sofa, while the Surround Air's manual suggests placing it ?nearby those suffering from breathing or other health problems.?
Ozone from ionizing air cleaners is a greater concern as sales increase. Ionizers now account for about 25 percent of the roughly $410 million per year spent on air cleaners as brands such as Brookstone and Oreck compete. (We plan to test the Oreck in a future report.)
INDOOR OZONE hits the radar
Experts agree that an ozone concentration more than 80 ppb for eight hours or longer can cause coughing, wheezing, and chest pain while worsening asthma and deadening your sense of smell. It also raises sensitivity to pollen, mold, and other respiratory allergy triggers, and may cause permanent lung damage.
Most indoor ozone is carried inside with outdoor air. Regulators have given indoor ozone less attention than outdoor ozone, since dilution and dissipation typically lower indoor levels by 20 to 80 percent. But Charles J. Weschler, professor of environmental and occupational health sciences at the Robert Wood Johnson Medical School in New Jersey, notes, ?Since we spend so much time indoors, exposure is often greater than outdoors.?
Recent studies of ozone's cumulative effects also raise concerns. A 14-year study of 95 urban areas in the U.S. found a clear link between small increases in ozone and higher death rates. The study looked at days when outdoor ozone concentrations didn't exceed the Environmental Protection Agency's 80-ppb standard over eight hours, according to the study's lead author, Michelle L. Bell, assistant professor of environmental health at Yale University's School of Forestry and Environmental Studies.
?We were able to tease out the relationship between ozone and mortality, even accounting for each day's weather and particulate pollution,? Bell said in an interview. ?A small increase in ozone was associated with a small increase in mortality and a larger increase with a larger increase in mortality, even in cities with low ozone levels.? The study predicts that a 10-ppb increase in ozone over eight hours could lead to roughly 3,700 premature deaths per year in those cities.
Another ozone study conducted in 2001 over six months in southern New England by the Yale University Center for Perinatal, Pediatric, and Environmental Epidemiology links ozone levels well below the EPA's 80-ppb standard to a higher risk of respiratory symptoms and use of rescue medication for children with severe asthma. Indeed, the study found ill effects even on days when ozone levels were 20 ppb lower than the EPA standard over eight hours.
OZONE RAISES OTHER THREATS
While ozone dissipates indoors, it can create other pollutants in the process. Research suggests that ozone reacts with the terpenes in lemon- and pine-scented cleaning products and air fresheners, creating formaldehyde--a carcinogen--and other irritants. Those byproducts can be absorbed by beds and carpets, and be released over an extended time frame. Research has also found that ozone reacts with terpenes to create additional ultrafine particles, which are hard to filter and can go deep into lungs.
A regulatory black hole
Ionizers such as the five we focused on are adding ozone indoors just as regulators work to cut ground-level ozone created outdoors as pollutants react with sunlight. The federal EPA's acceptable outdoor level is 80 ppb over eight hours. This year the California EPA recommended lowering the state's outdoor limit to 70 ppb. World Health Organization standards are tougher at 60 ppb over eight hours.
Several states, the EPA, and Canada have issued warnings about ozone generators, a small segment of the air-cleaner market. While ionizers emit ozone as a byproduct, ozone generators create it by design and purport to offer health benefits. Consumer Reports found two such models Not Acceptable as early as 1992.
The Consumer Product Safety Commission is reviewing scientific and government data on all air cleaners that create ozone. The CPSC is also evaluating whether the 50-ppb industry standard is adequate protection for consumers, and it may recommend a lower limit. A report is expected later this year.
No federal agency sets indoor ozone limits for homes, however. The EPA has authority over ozone outdoors, not indoors, though it publishes booklets on indoor air quality and runs the Indoor Air Quality Information Clearinghouse. Interestingly, the EPA doesn't take a strong position for or against buying any air cleaner.
The Food and Drug Administration regulates medical devices but says air cleaners aren't covered because manufacturers make only vague, health-related claims, rather than claims related to specific diseases. Nonetheless, the 50-ppb ozone limit for medical devices is also the threshold used in the industry test.
Some manufacturers tacitly acknowledge that their ionizers create ozone and may pose risks. Brookstone's owner's manual suggests that ?any person suffering from heart, lung, or respiratory illness should consult his or her physician before using this unit.? But that advice is buried deep in the manual's text.
The bottom line: Consumers Union believes that the CPSC should set indoor ozone limits for all air cleaners and mandate performance tests and labels disclosing the results. CU also believes that the Federal Trade Commission should take a close look at air-cleaner ads to determine whether they include unsubstantiated and deceptive claims.
In the meantime, we recommend avoiding ionizers that performed poorly or emitted significant ozone in our tests. ?We can't guarantee safety at any ozone level, so it makes sense not to contaminate your living space,? says Jonathan Samet, M.D., chairman of the epidemiology department of the Johns Hopkins Bloomberg School of Public Health.