Abstract: At approximately 12:30 p.m. on or about May 20, 1990, Employee #12 opened a bleed-off valve to the compressor oil reserve to remove oil from the ammonia lines. A sudden surge in the ammonia pressure line that went to the oil receptacle caused the line to blow loose from the oil receptacle. Oil, gaseous ammonia, and liquid ammonia sprayed into the work area of the Monfort engine room 05. Employee #12 then put on SCBA and entered the release area to shut off the valve. His attempt was unsuccessful and he suffered chemical burns. He then called the fire department to handle the release. At approximately 12:42 p.m., the fire department responded by sending six men on three trucks. Employees #8 and #9 entered the release area after getting the valve location from Employee #12, but they could not locate the correct valve and exited. Employee #8 then re-entered the release area alone and shut off the valve. Because they wore bunker gear, not chemical hazmat suits, Employees #8 and #9 suffered chemical burns to their groins. Employees #10 and #11 were then instructed to enter the area with full gear to contain and neutralize the ammonia release. They suffered skin irritation and some blistering. Ventilation fans were placed to blow the ammonia outside, but the Monfort ventilation was pulling the ammonia back into the plant. An employee of Anderson Electric donned Monfort SCBA with the aid of the Marshalltown Fire Department, entered the release area, and changed the ventilation. Employees #8 and #9 were taken by ambulance to the hospital; Employee #12 went to the hospital on his own. On or about May 21, 1990 at approximately 6:00 a.m., Employees #1 through #7 started work at MSP, a subcontractor for Monfort. A strong ammonia smell was noted by all MSP employees and they were issued 3M 8710 respirators. At approximately 9:30 a.m., Employee #1 noticed that Employee #3 had passed out and was slumped across the floor. Employee #1 called for help, Employee #4 brought a stretcher, and Employee #7 removed Employee #1's respirator. Employee #3 was taken outside to a loading dock. The company nurse and ambulance were called. Employees #1, #3, and #5 were taken by ambulance to the hospital. A few minutes later, Employees #6 and #7 were taken in a pickup to the hospital. Employees #2 and #4 were taken a few minutes later to the local hospital.