White Phosphorus is a dangerous explosive that combusts immediately and spontaneously under heat or impact. It has a reputation for sensitivity to friction and it is easy to ignite and deflagrate. It is a common ingredient in fireworks and signal flares and in some types of incendiary weapons. It quickly self-oxidizes in air. The resulting oxidation produces sulfur dioxide and phosphoric acid. It has a high heat of formation, and, because of its high energy density and good performance, is used in various military and industrial fire suppression systems. It is used in some munitions where a rapid and intense fire is required and when the smoke is desirable as an obscurant. The phosphoric acid, in sufficient quantity, will cause severe burns and destruction of the flesh (necrosis). For this reason, phosphorus is considered a dangerous war material. It is one of the few compounds that will burn in water. White phosphorus is pyrophoric to organic material. It reacts with lipids found in the skin and causes deep burn wounds. The high reactivity of white phosphorus results in the creation of acidic compounds that are toxic to the skin and muscle tissue. It is used in some types of incendiary weapons to cause serious injuries to people.