Prof. Dr. David J. Brenner and his research group at Center for Radiological Research, Columbia University Irving Medical Center has demonstrated that low doses of Far-UVC light (222 nm) inactivate 99.9% of aerosolized seasonal coronaviruses HCoV-229E and HCoV-OC43, when exposed in aerosol droplets of sizes similar to those generated during sneezing and coughing. As all human coronaviruses have similar genomic sizes, far-UVC light would be expected to show similar inactivation efficiency against SARS-CoV-2 and other human coronaviruses. Recently, his team work was published in the journal Scientific Reports, Nature Publication [1].
Corona virus disease 2019 (COVID-19) was first reported in December 2019 and then characterized as a pandemic by the World Health Organization on March 11, 2020. Globally, as of 6:32 pm CEST, 19 July 2020, there have been 14,043,176 confirmed cases of COVID-19, including 597,583 deaths, reported to WHO [2]. Given the rapid spread of the disease, including through asymptomatic carriers [3], it is of clear importance to explore practical mitigation technologies that can inactivate the airborne virus in public locations and thus limit airborne transmission.
Some of the researchers reported that ultraviolet (UV) light exposure is a direct antimicrobial approach and its effectiveness against different strains of airborne viruses has long been established [4-6]. The most commonly employed type of UV light for germicidal applications is a low pressure mercury-vapor arc lamp, emitting around 254 nm. However, while these lamps can be used to disinfect unoccupied spaces, direct exposure to conventional germicidal UV lamps in occupied public spaces is not possible since direct exposure to these germicidal lamp wavelengths can be a health hazard, both to the skin and eye [7-8].
By contrast far-UVC light (207 to 222 nm) has been shown to be as efficient as conventional germicidal UV light in killing microorganisms, but studies to date suggest that these wavelengths do not cause the human health issues associated with direct exposure to conventional germicidal UV light [9-12].
Figure 1 Buonanno et. al. show for the first time that far-UVC efficiently inactivates airborne aerosolized viruses. Infection of human lung cells from irradiated aerosolized alpha HCoV-229E as function of dose of far-UVC light. Representative fluorescent images of MRC-5 normal human lung fibroblasts infected with human alphacoronavirus 229E exposed in aerosolized form. We can refer further details in reference [1].
Based on their results, the researchers estimate that continuous exposure to far-UVC light at the current regulatory limit would kill 90% of airborne viruses in about 8 minutes, 95% in about 11 minutes, 99% in about 16 minutes, and 99.9% in about 25 minutes.
In their study reviewed that far-UVC light is anticipated to have about the same anti-microbial properties as conventional germicidal UV light, but without producing the corresponding health effects. Should this be the case, far-UVC light has the potential to be used in occupied public settings to prevent the airborne person-to-person transmission of pathogens such as coronaviruses.
This is one of the most interesting and emerging reports to handle coronavirus. “Because it’s safe to use in occupied spaces like hospitals, buses, planes, trains, train stations, schools, restaurants, offices, theaters, gyms, and anywhere that people gather indoors, far-UVC light could be used in combination with other measures, like wearing face masks and washing hands, to limit the transmission of SARS-CoV-2 and other viruses.”
References
1. M. Buonanno, D. Welch, I. Shuryak, D.J. Brenner, Scientific Reports, 10, 10285 (2020), https://doi.org/10.1038/s41598-020-67211-2.
2. World Health Organization. Coronavirus disease (COVID-2019) situation reports. Available on: https://covid19.who.int/.
3. N. van Doremalen, et al. N. Engl. J. Med, (2020).
4. W.J. Kowalski, Ultraviolet Germicidal Irradiation Handbook: UVGI for Air and Surface Disinfection. New York: Springer, (2009).
5. E.I. Budowsky, et al. Arch. Virol. 68(3-4), 239–47 (1981).
6. Z. Naunovic, S. Lim, E.R. Blatchley, Water Res. 42(19), 4838–46 (2008).
7. A. Trevisan, et al. Photochem. Photobiol. 82(4), 1077–9 (2006).
8. S. Zaffina, et al. Photochem. Photobiol. 88(4), 1001–4 (2012).
9. R.B. Setlow, et al. Proc. Natl Acad. Sci. USA 90(14), 6666–70 (1993).
10. D. Balasubramanian, J. Ocul. Pharmacol. Ther. 16(3), 285–97 (2000).
11. M. Buonanno, et al. PLoS One 11(6), e0138418 (2016).
12. M. Buonanno, et al. Radiat. Res. 187(4), 483–491 (2017).
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News written by
Dr. A. S. Ganeshraja
National College
Thiruchirappalli