Abstract: At approximately 2:30 p.m. on February 17, 2010, Employee #1 was working on a hog farm. He was in the utility hallway of a hog barn. The hog barn consisted of two confinement rooms (east and west) separated by the utility hallway. Employee #1's responsibilities consisted of checking the health of the hogs, which included providing them with food and water and administering antibiotic shots. Chores for each building took approximately 30 to 40 minutes, or approximately 15 minutes for a half-full building. At the time of the incident, a coworker was pumping the manure holding tank from beneath the west confinement room. The coworker stated that he saw Employee #1 arrive on site, but he didn't know when Employee #1 entered the building. Employee #1's coworker had started pumping around 8:45 a.m. that morning and was almost finished when the incident occurred. Manure was pumped from the south side of the building into a tank that was pulled by a tractor to an offsite concrete pit and unloaded. According to two other coworkers, one of the two manure pit fans was ordinarily disconnected while the pumping took place, because the pump shaft was placed into the fan hole. The coworker pumping manure did not notice anything unusual during the process. Employee #1 was working alone and was found unconscious at the north end of the utility hallway that separates the west and east confinement rooms. According to the final coroner's report, the immediate cause of death was acute respiratory failure due to hydrogen sulfide poisoning. When the fire department responded to the incident at 3:17 p.m., air measurements were collected inside the building using a four-gas meter. Hydrogen sulfide was measured at 42 to 44 ppm near the north service door, and carbon monoxide was measured at 30 ppm in the east hog confinement area. According to the sheriff's report, the north and south service doors had been open for an unknown amount of time, which most likely ventilated the hallway prior to the fire department's air measurements.