Field Study and Evaluation of KrCl* Far UV-C Device Capability for Inactivation of Phi6 Bacteriophage.

Far UV-C is an effective disinfection method that can be deployed in occupied areas. Commercially available krypton chloride (KrCl*) excimer lamps filtered to emit at 222 nm are effective in disinfecting pathogens and is safe for human exposure up to an allowable threshold exposure, which is much longer than for conventional UV lamps emitting at 254 nm. Laboratory and controlled field testing of a filtered KrCl* excimer lamp for disinfection of a virus suspended in a thin film aqueous solution in an occupied office setting was conducted. Complete inactivation of almost 6 logs (99.9999%) of Phi6 bacteriophage was achieved in ~20 minutes of exposure time in a field setting, equivalent to a dose of about 10 mJ/cm 2 . The Phi6 inactivation rate constant for the field test results were not statistically different from laboratory values (P>0.05, paired t-test). When positioned at 1 m distance from possible human exposure, this device can be used safely for almost 4.5 hours of continuous direct exposure without any acute or long-term adverse health effects. This study illustrates the applicability and deployment of Far UV-C for pathogen reduction and can help in decision making for implementation of Far UV-C for disinfection in human occupied environments.