In the race to find an effective solution that can sanitise large spaces from COVID-19, ultraviolet light seems to be a strong contender. Ultraviolet light of between 200-280 nm wavelength is known as UV-C and is known to be harmful to cell tissue.
Ultraviolet light of this wavelength is present in sunlight as well, but it is filtered out by the ozone layer in the Earth's atmosphere. UV-A and UV-B (320-400 nm), which are less harmful and closer to the visible spectrum of light are what pass through. These rays are responsible for giving you a sunburn.
UV-C light of specifically 254 nm in wavelength has been used to sanitise devices and kits for a while. However, exposure to humans for a long period can cause skin cancer.
Research shows that UV-C light has been effective in altering the cell structure in SARS-CoV-1 virus, which is also a coronavirus that caused SARS. Exposure to UV-C light of 254 nm for a period of 10 minutes was found to deactivate the virus, in comparison to other wavelengths of UV light.
Given this effectiveness of deactivating viruses and bacteria, many companies are building devices that use UV-C light to sanitise spaces. In New York, the government is sanitising buses and trains at depots using UV lights.
Hospitals plan to install UV-C lights at ceiling height and install fans that draw up air from below to that height to destroy viruses and bacteria. Other companies are making boxes and cupboards with UV-C light in them to sanitise personal protective equipment and other items.
However, using UV-C is only one option. Given that it needs at least 10 minutes of exposure to be effective, it is just one solution for spaces that are static. Other methods of disinfection will have to be used in conjunction with other methods of disinfection.
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