Abstract: At 4:45 a.m. on October 9, 2020, an employee was working for a firm that manufactured iron and steel pipe and tubing from purchased steel. In this incident, he was operating a "943" annealing furnace. He was monitoring recently annealed metal tubes as they exited the furnace. Some tubes exiting the furnace had become jammed on a conveyor. The employee approached the conveyor at a location where a large and visible exhaust hood was approximately 1 foot (0.3 m) above the conveyor. The exhaust hood carried away carbon monoxide and other gases that were normally emitted from the tubes as they cooled. The employee disconnected a chain, crossed between two sections of the conveyor, and positioned his head and upper body inside the exhaust hood. The employee worked underneath and primarily inside the hood manipulating the tubes on and off for about 17 minutes. His supervisor also assisted the employee for several minutes underneath the exhaust hood and then left. A short time later the supervisor discovered the employee passed out on the floor. An ambulance was summoned, and the employee was transported to a medical center. He was transferred from there to a general hospital, where he was admitted. He received hyperbaric treatment, which is used to treat severe carbon monoxide poisoning. After reviewing the employee's medical records, OSHA's Salt Lake City laboratory was able to determine the levels of carbon monoxide exposure and extrapolate an 8-hour TWA of carbon monoxide exposure. The employee was exposed to CO levels of 115.7 ppm. The employee and the supervisor both worked beneath an exhaust hood designed to remove toxic gases including, but not limited to, carbon monoxide, which was emitted after the annealing process. The amount of COHb in the employee's blood reached a calculated peak level of 33.2 percent. At the calculated peak level of 33.2 percent, symptoms in health adults would include severe headache, dizziness, nausea, vomiting, and cognitive impairment.