Abstract: A movable overhead ventilation assembly is provided for use in a work facility to be positioned in close proximity to a source of airborne environmental material. The ventilation assembly includes a supporting frame located within the work facility. The frame includes a longitudinally-disposed overhead track. A movable chassis is carried by the track. A ventilation housing is carried by the chassis for overhead translational movement of the ventilation housing within the work facility. The ventilation housing includes a plurality of walls, and has at least two openings therein defining respective inlet and outlet zones thereof. An exhaust fan is located within the ventilation housing between the inlet zone and the outlet zone for creating an upwardly moving air stream in the area surrounding the source of airborne environmental material.