Abstract: At approximately 3:45 p.m. on January 25, 1991, Employees #1 and #2 were treating water to remove contaminants from the water system. Alarms on the monitors went off, alerting the employees to the presence of hydrogen sulfide gas or other contaminants. The hydrogen chloride and iron sulfide used, when mixed, could precipitate hydrogen sulfide gas. Both employees experienced pain in the chest, lost consciousness, and fell to the ground, but regained consciousness after a short period of time. Both men were taken to Coalville Hospital, where they were treated, given oxygen, and released, suffering no aftereffects. It was unlikely that the alarms malfunctioned.