A Gas mask is a kind of mask that fits over the face area and nose . The mask forms a sealed cover over the nose and mouth , but may also cover the eyes and other vulnerable soft tissues of the face . Some gas masks are also respirators , though the word gas mask is often used to refer to military equipment ( e.g. Field Protective Mask , etc. ) ( The user of the gas mask is not protected from gas that the skin can absorb . )