The most direct way to limit the spread of the virus is to inactivate it within a short period of time after production. In this case, bactericidal ultraviolet rays at 254 nm are effective, but direct use can cause damage to the skin and eyes. In contrast, far ultraviolet (207-222 nm) can effectively kill pathogens without causing damage to the exposed parts of the human body.
Previous studies have shown that 222 nm far ultraviolet light can effectively kill influenza viruses. Scientists have extended these studies to explore the effects of far ultraviolet light on human coronaviruses αHCoV-229E and βHCoV-OC43.
The results showed that low doses of 1.7 and 1.2 mJ/cm2 inactivated 99.9% of the nebulized coronavirus 229E and OC43. Since all human coronaviruses have similar genome sizes, it is expected that far ultraviolet light will show similar inactivation efficiency to other human coronaviruses (including SARS-CoV-2).
According to the results of beta-HCoV-OC43, at a low exposure intensity of 3 mJ/cm2/hour, continuous extreme ultraviolet light exposure in public places can complete 90% of the virus inactivation within 8 minutes and 95% of the virus within 11 minutes Inactivation, 99% is inactivated within 16 minutes, and 99.9% is inactivated within 25 minutes. Therefore, the low dose rate of far ultraviolet radiation can safely and greatly reduce the coronavirus in public places.