Far-UVC (also far-UV or far-UV-C) is light with a wavelength of 200–235 nm. It is a type of germicidal ultraviolet (GUV) light, which includes the whole UVC and parts of the UVB spectrum. Far-UVC has emerged as a highly promising approach to indoor air disinfection, offering enhanced effectiveness and safety compared to conventional 254 nm upper-room GUV systems.