Inactivation of MS2 Phage Aerosols by Non-thermal Plasma Exposure

Herek Clack, Tian Xia, Abby Kleinhekse, Eric M. Lee, Zhong Qiao, Krista M. Wigginton

Infectious aerosols pose threats to human and animal health.  Available technologies for preventing transmission of infectious aerosols either rely on physical filtration, relatively slow ultraviolet inactivation, or a combination of both, criteria that can limit broader application for preventing disease transmission. A generic packed bed non-thermal plasma (NTP) reactor has been constructed to demonstrate and assess the effectiveness of NTPs in inactivating infectious aerosols. When energized between 12 and 30 kV, the reactor produces within the packed bed a distributed corona discharge consisting of electrons, ions, and radicals that are thought to attack the bacterial cell wall or the viral capsid or lipid layer, ultimately resulting in inactivation. Results based on aerosolized bacteriophage MS2 indicate progressively increasing inactivation efficiency with increasing applied power, reaching 2.3 log reduction in infectious MS2 after NTP treatment, based on E.coli plaque assays.  Quantitative polymerase chain reaction (qPCR) analyses find little change (~ 0.35 log) in the abundance of MS2 genome upstream and downstream of the packed bed NTP, demonstrating that physical filtration played only a very minor role due to the high porosity of the packed bed.  Accordingly, the bed induced only very minor (45 Pa at 171.5 litres per minute) pressure drop in the air stream.  Ozone concentrations varied, but an ozone filter designed for consumer electronics adsorbed more than 90% of generated ozone.

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