Abstract: On October 31, 1991, the company instructed Employees #1, #2, and #3 to replace three valves on a hydrofluoric acid line that ran from the kiln to a recovery unit. The kiln was shut down in the morning to stop production and the system was pumped out to remove hydrofluoric acid from the line. The company expected residual acid in the line. Employees #1, #2, and #3 were notified to begin after lunch. Work began about 2:00 p.m. Full body disposable acid suits, rubber gloves, and air supplied respirators were worn by the employees. After the employees broke into the line and removed the first valve, 1 to 5 gallons of hydrofluoric acid leaked onto the floor. This spill produced a fog but the employees kept working, taking three breaks to get air and to change suits. At approximately 5:00 p.m., Employee #2 left the area due to a burning foot. He washed his foot and went to the medical area where they soaked his foot in Zephiran solution for 30 minutes and applied calcium gluconate ointment. Employee #2 was given a copy of the treatment protocol and sent home with instructions to go to the hospital if pain persisted. At 9:00 p.m., Employee #2 reported to an area hospital and gave the physician the treatment protocol. The physician did not follow the procedure and only applied an ointment to the foot, administered two pain shots, and wrote a prescription for pain pills. On the morning of November 1, 1991, Employee #2 was in tremendous pain. He called the plant nurse and was instructed to go to another area hospital. The plant nurse called ahead to instruct the hospital. Employee #2 arrived at the hospital at approximately 9:00 a.m. The foot was covered in blisters, and he was treated with calcium gluconate administered through femoral catheters for several days. Employee #2 was hospitalized for 7 days and several toenails were removed. After Employee #2 left the work area on October 31, Employees #1 and #3 continued to work. Employee #3 went home at 4:00 p.m. on that day. He awoke on November 1 with burning feet and was properly treated by a private physician. Employee #1 returned to the work area on November 1 to complete the job. He began to experience burning of his feet. He reported to the medical area and was sent to the area hospital, where he was properly treated. Employee #1 was hospitalized. The system was not neutralized before the employees broke into the line.