Report
Investigation on Practical Usefulness of Body-worn Devices that Claim to Release Chlorine Dioxide
2017 Volume 32 Issue 4 Pages 222-226
Details
2017 Volume 32 Issue 4 Pages 222-226
Small portable devices worn as a name tag hanging around the neck or as a pen in front shirt pocket are sold in Japan. It is claimed that these devices can inactivate viruses and kill bacteria by releasing chlorine dioxide gas and that they are good for the control of air-borne pathogens. The reliability of such claims was investigated in four selected devices from four companies. The devices were scrutinized for their virucidal and bactericidal abilities against air-borne viruses and bacteria on agar plates, respectively, under temperature and humidity similar to room conditions in winter season set at 23°C and 30%, respectively.
The viral fluid of influenza A/Aichi/2/68 strain virus that propagated in the allantoic fluid of fertilized hens' egg was atomized using a nebulizer in a 25 m3 space closed environment; 80 L of air was sampled at a distance of 20 cm from the device, filtrated through a gelatin filter to trap the aerosol that contained the virus, and the amount of active virus was titrated using plaque assay. Viral loads were found to be similar between viral samplings in the air collected from the site close to the device for all devices and in the controlled air, indicating that no virucidal activity was found against the air-borne influenza viruses with selected devices in these conditions.
For bacterial experiments, an agar plate on which an aliquot of Staphylococcus aureus or Pseudomonas aeruginosa stock in the broth was spread and placed above the device at a 20-cm distance for 20 min and incubated to count the number of bacterial colonies. The amount of live bacteria on the plate was also found to be similar between the groups of those placed in the air close to the device and those in the controlled air for all devices and for both bacteria species, indicating no bactericidal activity against these bacteria with selected devices in these conditions.
In addition, the gas concentrations of chlorine dioxide released by devices were measured at a 10-cm distance from each device. The detected gas concentration was found very low or zero ppb in every product.
