Abstract: On April 23, 1999, Employees #1, #2, and #3 were preparing to clean caked-on flour from the inside of a 40-ft silo. The silo had been inspected by the entry supervisor, but he failed to recognize the loose flour at the base of the silo and on the floor of the basket at the top of the silo as a hazard to entry. Employee #2 was at the top of the silo when he noticed that the basket was not hanging straight and had approximately 18 in. of loose flour on the basket floor. He shook the basket and the flour fell in a cloud. Employees #1 and #3 were standing at the entry hatch at the base of the silo and saw the flour cloud, so they backed away to avoid the dust. When the cloud reached the non-explosion proof halogen light placed at the lower entry point, it ignited. Employee #2 received arm, chest, and head burns, and Employee #3 received facial burns. Employee #1 was not injured.