Lamps that use ultraviolet light to kill germs can inactivate coronavirus, but they are not all safe and it is not clear how good a job they do at killing the virus, the US Food and Drug Administration said Wednesday.
The FDA said ultraviolet-C (UVC) wavelengths are better than UVA and UVB light at destroying viruses, but UVC lamps still have their limits.
“The effectiveness of UVC lamps in inactivating the SARS-CoV-2 virus is unknown because there is limited published data about the wavelength, dose, and duration of UVC radiation required to inactivate the SARS-CoV-2 virus,” the FDA said in a newly posted statement.
Plus the lamps only work in limited circumstances.
“It is important to recognize that, generally, UVC cannot inactivate a virus or bacterium if it is not directly exposed to UVC. In other words, the virus or bacterium will not be inactivated if it is covered by dust or soil, embedded in porous surface or on the underside of a surface,” the FDA said.
There’s been an explosion of products on offer to fight coronavirus, including germicidal lamps. The World Health Organization warns against trying to use them to disinfect human skin, including the hands.
In addition, some UVC lamps generate ozone, which can irritate airways.
“Some UVC lamps contain mercury. Because mercury is toxic even in small amounts, extreme caution is needed in cleaning a lamp that has broken and in disposing of the lamp," the FDA added.