Japanese scientists have investigated the use of UV disinfection for the effective management of COVID 19.
UV radiation within the wavelength range of 200–300 nm effectively kills pathogenic microorganisms, although it poses a risk of protein and DNA damage in humans.
In this study, researchers from Nagoya City University in Japan, investigated the effectiveness of different UV wavelengths in inactivating two variants of SARS-CoV-2.
The study revealed that the 220 nm UV light, considered safe for humans, had comparable inactivation efficacy to the hazardous 260 nm light, for both the variants.
The global outbreak of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and its new variants has created a need for effective disinfection technologies to protect against harmful pathogens.
While vaccines offer some protection, their effectiveness against future variants is uncertain. Therefore, additional strategies are important during the pre-vaccine stage.
UV irradiation has emerged as a safe, effective, and convenient strategy to inactivate and eliminate disease-causing micro-organisms.
Professor Takahiro Matsumoto from the Graduate School of Design and Architecture, Nagoya City University, along with his team, found that both omicron BA.2 and BA.5 variants have almost identical UV inactivation properties.
Although the inactivation rates were highest at 260 nm, the rates obtained with 220 nm light delivered similar results.
“The findings highlight the potential of far-UVC light as a safe germicidal option,” Matsumoto said.
“The comparable inactivation efficacy between 220 nm and 260 nm light suggests that far-UVC light could be a promising and safe approach to mitigate airborne virus transmission.”
The team also found that the UV inactivation rate constants obtained in a liquid suspension were approximately 10 times lower than those previously obtained in an aerosol, suggesting the potential role of the Mie scattering effect in enhancing UV irradiance within aerosol droplets.
Additionally, the bacteria E. coli was used as a reference point to compare and understand the differences in inactivation and genome damage when compared to the SARS-CoV-2 omicron variants.
The study found that, above 240 nm, both SARS-CoV-2 and E. coli exhibit similar sensitivities to UV light, indicating UV-induced inactivation primarily targets genes (DNA or RNA). However, below 240 nm, significant differences were observed, which can be attributed to the difference in thickness of the protein layer covering DNA or RNA.
Matsumoto said the results pave way toward safe ultraviolet sterilization technologies being used in the near future.