Abstract: Employee #1 was working as a laborer for an electrical contractor. He was taking a lunch break at his work location, a warehouse. He was sitting on the curb, just outside the warehouse loading doors, smoking a cigarette. When he began to put out the cigarette on the ground, he noted that there was a powdery substance on the ground. When he placed the lit cigarette into this powdery substance, it caught fire, flared up, and burned both his hands. Employee #1 was transported to the University of California, San Diego, Burn Center, where he was hospitalized for 5 days with second and third degree burns to both hands. This substance was later identified as CADWELD, a magnesium oxide power used to make welded electrical connections. It is highly flammable. Employee #1 was aware of CADWELD, but he did not know that it was the substance on the ground. Neither Employee #1 nor his employer knew why this powder, which is normally kept in controlled containers, was at this location. The causal factor for this accident is that Employee #1 placed a lit cigarette in a highly flammable substance.