Abstract: A sterilizing unit for air ducts having an aluminum housing and at least one UV emitting probe extending downward into the duct. The upper surface of the unit overhangs the side walls for easy installation into the duct. At least one UV emitting probe in connection with the circuitry extends downward into the air duct. There is a light sensor, or monitor, that extends from the upper side of the unit to a point near the probe in order to provide a visual indication of the condition of the UV probe without exposure to the UV light. An on/off switch on the upper surface of the device allows for safety in servicing the sterilizing unit.