Ultraviolet radiation

Ultraviolet radiation

Subject : Science and Tech

Context: Dr. Jitendra Singh, Union Minister of State for Science and Technology, recently announced that the government would install Ultraviolet-C or UV-C Disinfection Technology in Parliament to mitigate the possibility of airborne transmission of SARS-CoV-2.

Concept:

Ultraviolet is the Sun’s natural radiation or light and covers wavelengths in the 100-400 nm range. The light ranges visible for humans is from 380–700 nm. There are three bands for UV — UV-C (100-280 nm), UV-B (280-315 nm) and UV-A (315-400 nm). The Sun transmits both UV-A and UV-B rays through the Earth’s atmosphere, while the ozone layer filters all UV-C.

Effects

• UV-B rays can reach the epidermis or outer layer of the human skin, causing sunburns
• It is also associated with causing skin cancer. UV-A rays can penetrate the dermis or the skin’s middle layer to age skin cells and indirectly damage cell DNA.
• Man-made UV-C radiation is known to have caused eye injuries and skin burns.
• Hospitals and laboratories have used UV-C radiation of 254 nm wavelength for decades to disinfect the air. It is also used to treat water.
• It could not penetrate through the human skin’s outer dead-cell layer or even the tear layer in eyes and was not a health hazard.
• Far-UVC light can reach the DNA of viruses and bacteria and kill them since they are smaller than human cells.
• UVC light can control the spread of airborne-mediated microbial diseases

UV-C and Corona virus

• The outer protein layer of SARS-CoV-2 can be destroyed using UV-C radiation.
• The 222-nm radiation, also known as far-UVC light, can kill airborne human coronaviruses such as alpha HCoV-229E and beta HCoV-OC43. This, however, is different from SARS-CoV-2, for which very limited data is available on the wavelength and duration required.
• 222 nm UV-C irradiation at 0.1 mW/cm2 killed 99.7% of SARS-CoV-2’s viral culture following a 30-second exposure
• UV-C irradiation effectively inactivated SARS-CoV-2 replication.

UV-C and disinfective applications

• UV-C air duct disinfection system can fit into any air-duct. It said calibrated levels of UV-C light is used to deactivate the virus in any aerosol particles, and the system was a perfect fit for malls, auditoriums, AC buses, educational institutions, and railways.
• a small disinfectant device that used UV-C radiation (222-254 nm), said it was developed specifically for non-living things. The device’s UV-C radiation could harm skin and eyes and the operator must use spectacles that protects from UV-C radiation
• While the Ministry of Science and Technology did not mention the wavelength of radiation or the duration for which it will be used, it mentioned that tests had shown that the product managed 99% disinfection.
• UV Light Technology offers disinfecting equipment to hospitals and pharmaceutical, one shouldn’t be exposed to UV-C, it takes hours to get a sunburn from UV-B, UV-C can do it in seconds.
• UVC light (207–222 nm) does not cause harm to mammalian skin.