UV light has been used widely in disinfection with a wide range of medical and non-medical products available in the market. In the time when the whole world is fighting against the corona-virus outbreak, LEDs that deliver virus killing UV lights might be a practical solution for preventing infection.
UV light is germicidal because it inactivates microorganisms by destroying nucleic acids and disrupting their DNA with its short wavelength. In addition, oxygen can also absorbed energy from UV light to form ozone for disinfection.
According to current understanding, UV light with a wavelength of 200-280nm is most germicidal. For different microorganisms, the effect of UV light varies. Mercury light has served as a UV light source for long with a irradiation wavelength of 253.7nm. With improved development in LED technology, varied LED can deliver UV light with specific wavelengths. UV LED-based applications with increased power and varied wavelengths are expected to be the next-gen disinfection products for medical uses.
The effect of UV germicidal irradiation depends on the temperature and humidity of the environment. The suggested time for UV light exposure is at least 30 minutes but it will take longer time to achieve the same effect when it is below 20 degree or over 40 degree Celsius and relative humidity exceed 60%. To more effectively and efficiently destroy bacteria and viruses, NSF International has revised drinking water treatment standard with UV LED technology included.
Then over corona-virus is a kind of positive-sense single-stranded RNV virus, same as the SARS and MERS virus. Researches on SARS found that this kind of virus is sensitive to heat radiation and UVC light and can be diminished when exposure to UVC irradiation stronger than 90 μW/cm2. Thus, in theory, UV light would be able to destroy the novel corona virus (2019-nCov). However, no further research has shown the effect of UV light on viruses attached to droplet at the moment.
To prevent infection, washing hands often with soap and water and use alcohol to sanitize hands are still cortical way to avoid spreading of viruses.
