All fires involve the chemical reaction of the burning substance with oxygen in the air, the release of great amounts of heat, and the rapid conversion of the combustion products into gases. Uncontrolled burning may destroy property and human life. Fires are most frequently caused by carelessness, misuse of industrial equipment, spontaneous combustion of raw materials and finished products, static electricity, lightning, and arson.
Fires extinguished in their early stages and involving no losses constitute about 25% of the total number of fires. Only a small percentage of fires are major fires occurring in depots, warehouses, stores, and other places where goods are concentrated; nevertheless, the material damage resulting from these fires is considerable.