On January 25, 1999, a male fire fighter, 25-years of age, was performing a weekly equipment inspection on the engine to which he was assigned. The inspection required the victim to check the oxygen pressure in the cylinder, which is stored in the airway supply bag. Removing the airway supply gas, the victim opened the post valve charging the regulator. The regulator generated a loud pop and emitted a large ball of fire. The victim received first- and second-degree burns to his head, arms, and hands. NIOSH was notified of this incident by the International Association of Fire Fighters (IAFF) and on February 23, 1999, a Safety and Occupational Health Specialist, an Engineer, and a Physical Scientist from NIOSH investigated this incident.