Abstract: On August 29, 1990, four WS Bunch employees, engaged in paint contract work at an Arcadian fertilizer manufacturing plant, were returning from lunch and climbed to the fourth level of a structure used in the manufacturing of urea in order to perform sandblasting operations. The employees were beginning to put on their ppe when a nearby ammonia tank relief valve released twice, releasing anhydrous ammonia into the air. It surrounded Employees #1 through #3. Their coworker had descended one level to retrieve a glove. The exposed employees, who were not wearing their goggles or cartridge respirators, evacuated the tower, showered, and flushed their eyes. Oxygen was administered and they were transported to the nearest hospital by a rescue squad. Employees #1 and #2 were treated for chemical burns of the eyes, nasal passages, and other body parts and were released. Employee #3 was treated for similar burns and was held overnight. The employees who attempted to don their cartridge respirators during the ammonia exposure indicated that the respirators were ineffective in filtering out the ammonia.