Any exposure to products of combustion, superheated atmospheres, toxic gases, vapors, or dust, potentially explosive or oxygen-deficient atmospheres, or any condition that creates a hazard to the respiratory system. NFPA 1404, 2002 ed. Respiratory Protection. Equipment designed to protect the wearer from the inhalation of contaminants, (see FigureR. 6). NFPA 472, 2002 ed