Abstract: A compact, light-weight, disposable, and quick-fit rehumidification filter device adapted to fit flight-masks which deliver pressurized respiratory fluids to a human. The preferred embodiment is made up of a container, a continuous strip of micropore filter paper helically rolled so as to entirely fill the space defined by the cross section of the container, optional directionally louvered screens affixed to the container, and a securing mechanism which detachably secures the filter device to the flight-mask. The securing mechanism is adapted to mate with a retaining ring projection common to most flight-masks by use of a matingly threaded ring or by a structure which flexibly and resiliently clips onto the outer circumferential surface of the retaining ring projection. The filter paper acts as a humidification counter-exchange apparatus by first extracting moisture from exhaled breath, then subsequently returning moisture to dehumidified respiratory fluids being inhaled.