Abstract: A far-ultraviolet (far-UVC) disinfection device including a light source positioned within a housing and configured to emit a far-UVC light having an output wavelength of between about 206 nanometers to about 230 nanometers. There are one or more subject detection sensors positioned configured to detect the presence of one or more subjects and a controller in communication with the light source and the one or more subject detection sensors. The controller is configured to receive detection data from the one or more subject detection sensors and determine whether one or more subjects are within a range of the far-UVC light emitted by the light source. The controller is further configured to cause the light source to emit or cease emitting far-UVC light based on the amount of time one or more subjects are within the range of the emitted. far-UVC light.