Abstract: A rail car unloading aspiration unit includes a rail car nozzle for providing air conduits for feeding conditioned air to the rail car and for withdrawing air therefrom, ambient air being drawn between a weather shield, hood or cover and a fan chamber mounted on a heating chamber which forces ambient air to pass through a filter and be heated within the range of approximately 77.degree. F.-95.degree. F. The heated air is passed in proximity to ultra violet lamps after which the air is directed into the rail car nozzle and expelled into the interior of the rail car head surface above the product being unloaded. During the time that power is applied to the aspiration unit, the fan forces air to be drawn into the unit and conditioned, and the ultra violet lamps remain on. However, the heaters are selectively activated or deactivated as a function of the temperature of the incoming air in order to maintain the temperature of the air within the desired ranged prior to being exposed to the ultra violet lamps.