So-called personal air purifiers promise to protect users from harmful viruses and bacteria, but experts say the devices may not work in real-world conditions, Laura Johannes writes in the Wall Street Journal.
Personal air purifiers—such as the AirSupply Minimate from Wein Products—are meant to be worn around the neck. They work by emitting electrically charged particles called ions. In theory, the ions transfer their electric charge to harmful particles, which are then repulsed from the user because like-charged particles repel each other.
Wein partially funded research at the University of Cincinnati to test its product. The results were published in the journal Indoor Air in 2005. Overall, the device was found to clear the air of half of the test particles in 15 minutes and almost all of the particles in an hour and a half.
However, some experts are skeptical. Darryl Zeldin, scientific director of the National Institute of Environmental Health Sciences, says, "It sounds like it worked in a laboratory setting, but that doesn't say anything about whether it works in real life."
For instance, some researchers argue the purifiers may struggle to actually clear air. "If you sit next to a person in an airplane, this person will sneeze and cough during the entire eight-hour flight," says Werner Bischoff, an infectious disease specialist at Wake Forest Baptist Medical Center.
Moreover, many harmful germs are transferred via infected surfaces—which are unaffected by the purifier. Sergey Grinshpun, who the led the study, acknowledges that shortcoming, but adds "at least you reduce inhalation exposure."
Anecdotally, representatives from Wein and other manufacturers say that customer feedback has been positive. However, according to the Wall Street Journal, some of the devices' infection-fighting prowess may be the result of the antibacterial effect created by air pollutants, such as ozone. Stanley Weinberg, CEO and chairman of Wein, says his company's product emits only a small amount of ozone.
Ultimately, Bischoff says other common-sense methods might be a better way to guard yourself against infection than the purifiers. For instance, avoid touching your nose or mouth while on an airplane, he suggests (Johannes, Wall Street Journal, 3/16).
The takeaway: While personal air purifiers have shown some benefits in the lab, experts say it is unlikely that they will protect against germs and viruses in a real-world setting.