According to a new study by Columbia University’s Irving Medical Center, more than 99.9% of the coronaviruses present in aerosols were killed when exposed to a specific wavelength of ultraviolet light. The fact that viruses are killed by UV light is fundamentally nothing new. What is special about the current results is that this specific light is harmless to humans.
This could make it possible to disinfect rooms and areas in which people reside without endangering their health. The corresponding study was published on Thursday in the journal Nature.
It is so-called far UV light with a wavelength of 222 nm. Far UV-C light cannot penetrate the tear layer of the eye or the outer skin layer and therefore cannot reach or damage living cells in the body, as it does in a Communication from the university means. UV light, which is harmful to humans, is broad-spectrum UV-C light, which is used, for example, to disinfect medical facilities. Under no circumstances should there be people in it.
It has been proven in the past that distant UV light can deactivate influenza viruses. The new study expanded research to seasonal corona viruses, which are structurally very similar to the SARS-CoV-2 virus that triggers COVID-19.
Accordingly, the far UV light kills 90 percent of the viruses in the air within 8 minutes, 95 percent in 11 minutes and 99 percent in 16 minutes. After 25 minutes, 99.9 percent of the viruses are inactive.
“UV light does not distinguish between different types of coronavirus, so we expect it to kill SARS-CoV-2 in the same way,” said study lead author David Brenner. “Since SARS-CoV-2 is largely spread through droplets and aerosols, it is important to have a tool that can safely inactivate the virus, especially when there are people around,” continued Brenner.
In combination with other measures such as masks and frequent hand washing, the use of light could be an important tool, explains the scientist.
Beware of sun and UV lamps
The effect of UV light, which is also harmful to humans, on viruses has already led to a WHO warning. The health organization warns against exposing itself to too much sun to protect itself from the virus. The WHO also advises against using UV lamps to disinfect the hands or other skin areas in the corona crisis. These lamps generally emit broad spectrum UV light.