Context: Recently, it has been decided that Ultraviolet-C (UV-C) air duct disinfection systems would be installed in Parliament for mitigation of Covid-19.

Key Points

• It was developed by the Council Of Scientific And Industrial Research-Central Scientific Instruments Organisation (CSIR-CSIO).
• It is designed to fit into any existing air-ducts and the virucidal dosages using UV-C intensity and residence time can be optimised according to the existing space.
• The virus is deactivated in any aerosol particles by the calibrated levels of UV-C light.

Research has proved that UV-C radiation can destroy the outer protein coating of Covid-19 and is effective in inactivating the replication.

• UV-C radiation has been used to disinfect the air in hospitals, laboratories and also in water treatment, but these conventional germicidal treatments are done in unoccupied rooms as they can cause health problems.

Ultraviolet Light
It is a type of light or radiation naturally emitted by the Sun and covers a wavelength range of 100-400 nm (human visible light ranges from 380–700 nm).
UV is divided into three bands:

1. UV-C (100-280 nm): UV-C radiation from man-made sources has been known to cause skin burns and eye injuries.
2. UV-B (280-315 nm): Can only reach the outer layer of skin or epidermis and can cause sunburns and are also associated with skin cancer.
3. UV-A (315-400 nm): Can penetrate the middle layer of skin or the dermis and can cause aging of skin cells and indirect damage to cells’ DNA. 

UV-A and UV-B rays from the Sun are transmitted through the atmosphere and all UV-C is filtered by the ozone layer.
Safety for Humans

• The device was specifically developed to disinfect non-living things and the operator must use spectacles with UV-C radiation protection.
• However, few studies have shown that far-UVC light (207–222 nm) does not harm mammalian skin as it has a very limited range and cannot penetrate through the outer dead-cell layer of human skin or the tear layer in the eye.