Mark Vender
A new study in the Journal of Hazardous Materials has compared the effectiveness of ultraviolet radiation against air filtration to mitigate virus-laden aerosols in an occupied clinical room, with interesting results.
The study comprised three experiments.
First, it compared the effectiveness of germicidal ultraviolet radiation (GUV) at two different frequencies – 254nm (upper room) and 222nm (whole room) – against portable high efficiency particulate air (HEPA) filters to inactivate/remove airborne bacteriophage ϕX174. This is a virus harmless to humans that allows for experimentation in an occupied room.
Second, it measured how air mixing, using floor-mounted fans, changed the effectiveness of upper room GUV at 254nm.
And third, it measured the relative susceptibility of ϕX174, SARS-CoV-2, and Influenza A(H3N2) to GUV at 254nm and 222nm.
Through these experiments, the research team hoped to address a gap in the research and offer a better comparison of GUV to HEPA filters. Currently, the methodology and data used to calculate equivalent air changes per hour (eACH) for HEPA and GUV are different and comparisons across methodologies may be misleading.
The results highlighted the potential effectiveness of GUV. In poorly ventilated environments, GUV was able to deliver equivalent air changes to portable HEPA filters set at high filtration rates. The team also found that upper room GUV devices can be enhanced by increasing air mixing.
In terms of the different UV frequencies, 254nm GUV was found to be more effective at inactivating SARS-CoV-2 than ϕX174 virions, while 222nm GUV was more effective at inactivating both SARS-CoV-2 and H3N2 compared to ϕX174.
The full study is available here.
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