High Hazard. High hazard contents shall be classified as those that are likely to burn with extreme rapidity or from which explosions are likely. Low Hazard.* Low hazard contents shall be classified as those of such low combustibility that no self-propagating fire therein can occur. Ordinary Hazard.* Ordinary hazard contents shall be classified as those that are likely to burn with moderate rapidity or to give off a considerable volume of smoke.