Test results show that the virus could no longer be detected after seconds of exposure
New research from two independent studies provides data for the inactivation of SARS CoV-2 (the Covid-19 virus) with UVC light at 254 nm. Following the latest scientific advances, Propokan Pro updates the recommendations for use of the UVC HVAC system, with new, more beneficial values replacing the previously estimated averages based on old studies.
Italian scientists, when evaluating the virucidal effects of UVC irradiation, came to the conclusion that 3,7 mJ/cm2 provides a log3 reduction, that is 99.9% disinfection, of SARS CoV-2 (Covid-19 virus). Their study shows that this is enough to successfully inactivate the viruses in saliva remaining after an infected person coughing so that no spread can occur. The disinfection effect is evaluated by an in vitro SARS-CoV-2 (Covid-19 virus) infection assay, exposing live cells to the virus before and after UVC exposure. The survival of cells exposed to UVC-inactivated virus, and the death of cells exposed to an untreated virus, indicates successful disinfection.
Research from Signify and Boston University found 5 mJ/cm2 (for a log2 reduction) [2], which would correspond to 7,5 mJ/cm2 (for a log3 reduction). Since the start of the SARS CoV-2 pandemic, Dr. Anthony Griffiths, Associate Professor of Microbiology at Boston University School of Medicine, and his team have been working on developing tools to support scientific advancement in this field. During their research, they have treated inoculated material with different doses of UV-C radiation coming from a Signify light source and assessed the inactivation capacity under various conditions. The team applied a dose of 5mJ/cm2, resulting in a reduction of the SARS-CoV-2 virus of 99% in 6 seconds. Based on the data, it was determined that a dose of 22mJ/cm2 will result in a reduction of 99.9999% in 25 seconds.
Both studies show significantly reduced dose requirements compared to the previous estimate (20,1 mJ/cm2 for a log3 reduction)[3] which was based on an average for different related viruses in the corona viridae family.
In light of this new pre-publications, we at Propokan Pro have decided to adjust our dose recommendation for disinfecting SARS CoV-2 (Covid-19 virus). While the works presented indicates 3,7-7,5 mJ/cm2 for a log3 reduction, we have chosen to add a margin to this when updating our recommendations. Taking this into account, our new recommendations are 10 mJ/cm2 for a log3 reduction, down from 20 mJ/cm2.
Stay tuned for Propokan Pro’s upcoming article with more information regarding this!