Abstract: At approximately 10:30 p.m. on October 11, 2006, Employee #1, a saw operator, and Employee #2 were renovating the meat preparation area of a grocery store. Employee #1 was using a gasoline-powered concrete saw to cut the floor of the work area. They had been cutting for less than an hour when Employee #2 left for a brief period. Upon his return, he found Employee #1 slumped over. Employee #1 was pulled out of the room, and emergency medical personnel were summoned. Upon their arrival, the fire department determined that the level of carbon monoxide was 450 ppm in the work area and 300 ppm in the back of the store. They cleared the building and began ventilating it. Employee #1 was taken to a medical center, where he was treated in the hyperbaric chamber and then hospitalized. He had a carboxyhemoglobin level of 37, which dropped to 18 after he was on oxygen for two to three hours and spent one-and-a-half to two hours in the hyperbaric chamber. Employee #2 was taken to a different hospital, where his carboxyhemoglobin level was measured at 16.9. He received oxygen for two hours and was released. Even though ventilators were available, Employees #1 and #2 did not use them. They thought they had adequate ventilation for the short duration of the job.