A method and device for use in breathing where the ambient temperature is uncomfortable is the subject of the present invention. An air intake conduit is enclosed by a sack and communicates with a face mask that covers the nose and mouth of the wearer. Both the intake conduit and the enclosing sack extend in a curvilinear path over the head of the wearer to take advantage of heat normally lost through the head. A head covering may be used to further increase the efficiency of the heat exchange between the head and the air passing through the sack and the intake conduit. One-way valves on the inlet and outlet openings assure segregation of inhaled and exhaled air. Exhaled air is passed into the sack where it is held in heat exchange relationship with the incoming air moving through the conduit as well as with body heat radiated by the wearer's head. An exit opening at the end of the sack distal from the point where exhaled air enters allows the exhaled air to eventually pass from the sack.