Copyright and License information Ionizing air cleaners—those staples of infomercials and splashy magazine ads—are not only ineffective at removing contaminants from indoor air, but also may emit enough ozone to be a health concern. The effects may be even greater in people with respiratory problems, who make up 80% of the buyers of such devices. Those are the conclusions reached in tests of the units described in the May 2005 Consumer Reports (CR).CR tested five units (including the top-selling Ionic Breeze from The Sharper Image) and confirmed results reported in October 2003 rating most of the air cleaners “poor” at removing dust and tobacco smoke from the indoor environment. This time around, pollen was added as well, with similarly disappointing results. The cleaners were also tested for generation of ozone, a respiratory irritant. The results showed that some of the least effective models also emitted potentially harmful ozone levels.“We felt that it was particularly important to notify our subscribers that these air cleaners not only don’t remove particulates from the air, but they also put ozone into it,” says Jeff Asher, vice president and technical director of Consumers Union, the publisher of CR.

There is no regulatory standard for ozone emission by air cleaners; manufacturers claim to adhere to a voluntary standard of 50 parts per billion (ppb), a limit established by the Food and Drug Administration for medical devices. CR used Underwriters Laboratories Standard 867 to measure the units’ ozone levels from 2 inches away in a sealed polyethylene room. All five machines failed that test.To more accurately reflect actual use conditions, CR also tested the devices in an open laboratory, from distances of 2 inches and 3 feet. Two units failed this this test; the other three (including the Ionic Breeze) produced levels of 26–48 ppb at 2 inches and 2–18 ppb at 3 feet—still high enough by CR’s estimation to be of concern. “The levels were not what I would call of great imminent risk,” says Asher, “but it was of significant risk in the sense of being in an indoor environment, where we just don’t need more ozone.”The Sharper Image, which unsuccessfully sued CR over its 2003 report, has fired back, assailing the magazine’s credibility.

In a 6 April 2005 press statement, CEO Richard Thalheimer called the article “irresponsible in the way it casually and unscientifically speculates about public health and safety. . . . We continue to emphatically disagree with Consumer Union’s methods in evaluating the Ionic Breeze.”But health and engineering experts find the CR results troubling. “These levels make these devices inappropriate to use for asthmatic patients and for patients with respiratory disease,” says Peyton Eggleston, interim director of the Johns Hopkins Children’s Center.Richard Shaughnessy, an environmental engineer at the University of Tulsa who has researched air cleaners for many years, concurs, pointing out that “not only are people with respiratory illnesses and asthma the population targeted by most of these air cleaners, they’re also the ones who are most likely to be adversely affected in terms of exposure to small amounts of ozone.”Grinshpun SA1, Mainelis G, Trunov M, Adhikari A, Reponen T, Willeke K.Author information1Center for Health-Related Aerosol Studies, Department of Environmental Health, University of Cincinnati, OH, USA.

sergey.grinshpun@uc.eduAbstractNumerous techniques have been developed over the years for reducing aerosol exposure in indoor air environments. Among indoor air purifiers of different types, ionic emitters have gained increasing attention and are presently used for removing dust particles, aeroallergens and airborne microorganisms from indoor air. In this study, five ionic air purifiers (two wearable and three stationary) that produce unipolar air ions were evaluated with respect to their ability to reduce aerosol exposure in confined indoor spaces. hammacher schlemmer air purifier reviewsThe concentration decay of respirable particles of different properties was monitored in real time inside the breathing zone of a human manikin, which was placed in a relatively small (2.6 m3) walk-in chamber during the operation of an ionic air purifier in calm air and under mixing air condition. ionizer air purifier uk

The particle removal efficiency as a function of particle size was determined using the data collected with a size-selective optical particle counter. The removal efficiency of the more powerful of the two wearable ionic purifiers reached about 50% after 15 min and almost 100% after 1.5 h of continuous operation in the chamber under calm air conditions. In the absence of external ventilation, air mixing, especially vigorous one (900 CFM), enhanced the air cleaning effect. iq air purifier vs blueairSimilar results were obtained when the manikin was placed inside a partial enclosure that simulated an aircraft seating configuration. All three stationary ionic air purifiers tested in this study were found capable of reducing the aerosol concentration in a confined indoor space. The most powerful stationary unit demonstrated an extremely high particle removal efficiency that increased sharply to almost 90% within 5-6 min, reaching about 100% within 10-12 min for all particle sizes (0.3-3 microm) tested in the chamber.

For the units of the same emission rate, the data suggest that the ion polarity per se (negative vs. positive) does not affect the performance but the ion emission rate does. The effects of particle size (within the tested range) and properties (NaCl, PSL, Pseudomonas fluorescens bacteria) as well as the effects of the manikin's body temperature and its breathing on the ionic purifier performance were either small or insignificant. The data suggest that the unipolar ionic air purifiers are particularly efficient in reducing aerosol exposure in the breathing zone when used inside confined spaces with a relatively high surface-to-volume ratio.PRACTICAL IMPLICATIONS: Ionic air purifiers have become increasingly popular for removing dust particles, aeroallergens and airborne microorganisms from indoor air in various settings. While the indoor air cleaning effect, resulting from unipolar and bipolar ion emission, has been tested by several investigators, there are still controversial claims (favorable and unfavorable) about the performance of commercially available ionic air purifiers.

Among the five tested ionic air purifiers (two wearable and three stationary) producing unipolar air ions, the units with a higher ion emission rate provided higher particle removal efficiency. The ion polarity (negative vs. positive), the particle size (0.3-3 microm) and properties (NaCl, PSL, Pseudomonas fluorescens bacteria), as well as the body temperature and breathing did not considerable affected the ionization-driven particle removal. The data suggest that the unipolar ionic air purifiers are particularly efficient in reducing aerosol exposure in the breathing zone when they are used inside confined spaces with a relatively high surface-to-volume ratio (such as automobile cabins, aircraft seating areas, bathrooms, cellular offices, small residential rooms, and animal confinements). Based on our experiments, we proposed that purifiers with a very high ion emission rate be operated in an intermittent mode if used indoors for extended time periods. As the particles migrate to and deposit on indoor surfaces during the operation of ionic air purifiers, some excessive surface contamination may occur, which introduces the need of periodic cleaning these surfaces.