Abstract: Air contaminated with combustible dust particles is removed and subjected to a high density air scrubber which safely removes the fine combustible dust particles from the contaminated air. The resulting water saturated, cleansed air is mixed with a continuously regulated amount of drier outside air until a desired absolute humidity is achieved, the regulation being responsive to the relative humidity changes within a work area in which the humidity is to be controlled. The air mixture is then conveyed into the work area which imparts a known temperature rise thereto. The temperature rise lowers the relative humidity of the air mixture to the desired level.