Abstract: An ultraviolet germicidal irradiation device relating to reducing air-borne contaminants within air passing through an air-distribution duct. The device uses ultraviolet light source configured to produce germicidal UV-C light, a switchless current-conducting circuit configured to continuously conduct electrical current between a battery source and the at least one electrically-operated ultraviolet light source, and a housing to house electrically-operated ultraviolet light source and the switchless current-conducting circuit. The housing includes a mount configured to mount the housing within the air-distribution duct, a battery compartment adapted to hold the battery source, and at least one ultraviolet-light passage adapted to pass the germicidal ultraviolet light from the electrically-operated ultraviolet light source through the housing.