Respirator
a device for breathing through, worn over the mouth, or the nose and mouth, and secured by a bandage, strap, or other contrivance, to exclude injurious matters, such as smoke or dust, from the lungs, or to change the condition of the air by passing it through medicaments or gauze. Respirators are used by cutlers and other grinders to exclude the dust from the lungs, and also by firemen to prevent suffocation by smoke. Respirators for persons having weak lungs have several folds of fine wire gauze, which being warmed by the expired breath, in turn heats the inspired air.