An ultraviolet germicidal irradiation device relating to reducing air-bornecontaminantswithin air passing through an air-distribution duct. The device usesultraviolet light sourceconfigured to produce germicidal UV-C light, a switchless current-conductingcircuit configuredto continuously conduct electrical current between a battery source and the atleast one electrically-operatedultraviolet light source, and a housing to house electrically-operatedultraviolet lightsource and the switchless current-conducting circuit. The housing includes amount configured tomount the housing within the air-distribution duct, a battery compartmentadapted to hold thebattery source, and at least one ultraviolet-light passage adapted to pass thegermicidal ultravioletlight from the electrically-operated ultraviolet light source through thehousing.
