Abstract: At approximately noon on October 19, 1989, Employee #1 was cleaning an empty tank which is 14 feet long, 6 feet deep, and 16.5 inches in diameter at the opening. The employee was found unconscious inside the 2nd tank of the trailer at approximately 1 p.m. The tank contained solid residual of a fertilizer batch that was prepared with phosphoric acid sulfur and ammonium polyphosphate. The batch is liquid but after the field application the walls of the tank get dirty with leftover residual. Apparently, cleaning the walls and surfaces inside the tanks is done regularly. Employee #1 was not wearing any respiratory protection when he was found inside the tank. Employee #1 was initially taken to a local hospital and then taken to another hospital in another city where he died on October 20. The cause of death is not known.