UVC lamps have been used for decades in the hospitals and other healthcare settings to sterilize drinking water and to kill bacteria and viruses
Conventional UVC lamps inactivate the SARS coronavirus but are dangerous to the human skin and eyes when exposed to the light
Far-UVC light has similar germicidal efficacy as the conventional method but with lesser adverse effects on human health.
The COVID-19 pandemic has increased the demand for UV light to disinfect air and surfaces. Well, the UV rays are a type of electromagnetic radiation with a wavelength shorter than the visible light. There are three types of UV rays: UVA (315-400 nm), UVB (280-315 nm), and UVC (100-280 nm) present in the sunlight. The UVC and 90% of UVB rays do not reach the earth’s surface as the ozone layer in the atmosphere filters them out. The UVA and a small proportion of UVB rays cross the ozone layer to reach the earth’s surface. These rays cause adverse effects on the skin and eye. The UVA and UVB rays are less dangerous than the UVC rays. UVA causes aging and photosensitivity. On the other hand, UVB is a major risk factor for sunburn, skin cancer, and cataracts. Use sunscreen whenever you go outside in the sun to be protected.
Application of Radiations
UVC radiation is known as air, water, and non-porous surface disinfectant. It deactivates the virus if it comes in direct contact with the UV light. Due to its germicidal activity, UVC lamps have been used for decades in the hospitals and other healthcare settings to sterilize drinking water and to kill bacteria and virus. It has also been shown to inactivate the SARS coronavirus. Recent studies suggest that SARS-CoV-2 coronavirus spreads through air or direct contact. To prevent the rapid spread of the virus, it is crucial to invest in strategies to inactivate the virus present in the surroundings. The low-pressure mercury-vapor arc lamp is the commonly used UV light for the disinfection purpose. This conventional method emits a wavelength of around 254 nm that is hazardous to the skin and eyes. However, the far-UVC light emits a wavelength that ranges from 207 to 222 nm. It shows similar germicidal efficiency as the conventional method but with lesser adverse effects on human health. So, several researchers support the excimer lamps that emit the far-UVC light to be used in public locations to prevent the transmission of microorganisms like the SARS-CoV-2 coronavirus.
Several commercial consumer UV products are available in the market. UV wands, UV boxes, UV microwaves and multiple other products are being publicized to help with disinfecting commonly used household items. Along with this, large UV lamps are also available to disinfect the entire room. A large number of hospitals in the United States and other countries are now using UV lights to disinfect patient’s rooms and operating rooms.
Some UVC lamps also use ozone for effective killing of the virus. Time taken to disinfect a surface or a room is much less when ozone is combined with the ultraviolet. Studies showed that low doses of far-UVC rays were effective in inactivating 99.9% of the coronaviruses that caused SARS and MERS. Similarly, ozone itself can kill 99.99% of the pathogens. Combination of UV and ozone is more time and energy-efficient. As all the coronaviruses share a similar genetic component, it is believed that far-UVC rays could also help in inactivating the SARS-CoV-2 coronavirus.
There is limited evidence on the safety and efficacy of UVC rays in deactivating the SARS-CoV-2 virus. Researchers are working on improving the efficiency and decreasing the side effects of UVC light.