Abstract: A breathing apparatus for athletes to warm and moisturize inhaled air has an elongate housing having both lateral and downward curvatures with respect to the position of the apparatus when positioned over the mouth of the wearer. An oral aperture for disposition over the mouth of the wearer is disposed centrally of the housing on the concave side of the lateral curvature. A plurality of corresponding pairs of spaced-apart leaf members or vanes disposed within the housing. The leaf members are disposed so that the inner ends of the pairs of members form a chamber adjacent to the oral aperture, with the chamber having diminishing depth from front to rear so as to permit the leaf member ends to catch and distribute exhaled air along passages formed by the leaf members. The exhaled air warms and moisturizes the leaf members, which in turn warm and moisturize the inspired air to prevent damage to sensitive tracheal membranes of runners in cold weather.