Cold weather respiratory mask

Claim 1

A respiratory mask for use in severe arrid environments, said mask comprising, a first shell having nose and jaw portions defining an internal area of the shell of a configuration to cover the wearer's nose and mouth and said first shell defining at least one open area for the passage of respiratory air, retention means for retaining the mask on the user's face, a countercurrent medium positioned within the first shell internal area generally defined by the nose and jaw portions of the first shell and through which inhaled and exhaled respiratory air passes from said at least one open area, said medium having a multitude of air passages along which substantially all respiratory air travels, said medium partaking of the heat from exhaled air and the heat of condensation given up by exhaled water vapor condensing on said medium for subsequent transfer to a reverse flow of respiratory air, a second shell member positioned within the internal area defined by said first shell, said countercurrent medium confined between said first shell and said second shell and said first shell having a flap and defining an opening, said flap overlying and normally closing said opening wherein when the flap is opened, said opening permits insertion and removal of the countercurrent medium as well as providing a secondary course for respiratory air.