"As end-of-summer harvest time nears, grain storage facilities will be gearing up to accept crops from farmers' fields. Many of these products produce combustible dusts that can result in catastrophic explosions when there is a suitable mix of air and fuel, as well as an ignition source such as a hot bearing, overheated motor, misaligned conveyor belt, or when welding, cutting and brazing are taking place. According to U.S. Department of Labor statistics, since 1976, there have been 503 grain elevator explosions in the United States, resulting in 184 deaths and 677 injuries. The likelihood, severity and lethality of grain dust explosions and fires can be reduced by a few simple safety precautions."
Coffee Break Training - Fire Protection Series No. FP-2014-27
U.S. Fire Administration: http://www.usfa.fema.gov/