Abstract: At 7:45 p.m. on either May 24 or May 25, 2012, many workers were employed at a slaughterhouse. They were working on the B-shift, on the ham line in the converting part of the facility. At that time, the workers started smelling ammonia. The smell was coming from the Cut Floor area on the east side of the facility. The leak was above the adjacent cut floor room on the roof and 18.1 to 30.4 kilograms (40 to 67 pounds) of ammonia leaked for 25 minutes. The workers began evacuating, as directed by the B-shift supervisor, out the west door, where they encountered the ammonia cloud and began suffering ammonia-related injuries. The wind was blowing the ammonia cloud from east to west, and the cloud settled on the west side of the facility. There was no communication regarding the actual location of the leak, the wind direction, nor determination of the actual concentration of ammonia in the ham line/converting area before the evacuation order was given, by a horn, or when the workers left to exit through the cloud. The ammonia cloud they encountered during evacuation caused multiple instances of respiratory system distress. Thirty-eight employees sustained tissue irritation in the form of burning eyes or respiratory tract issues from the ammonia.