The UV radiation can be classified into three types according to their wavelength (UVA, UVB and UVC). These UV wavelengths differ in their biological activity and the extent to which they penetrate inside cells and microorganisms.
Out of these three, UVC has the highest disinfectant capacity because of its shorter wavelength and ability of this wavelength to interact with the RNA and DNA of the cells and microbes .
COVID -19 is from the coronavirus family and resembles SARS virus that was identified in 2002. Both these viruses attack primarily therespiratory system by rapidly multiplying itself inside the cells of human respiratory tract. To replicate itself these virus inserts its genetic instructions (RNA or DNA ) into the human cells which then reads the instructions and makes multiple copies of itself.