 Ammonium nitrate decomposes into the gases nitrous oxide and water vapor when heated (not an explosive reaction); however, it can be induced to decompose explosively by detonation.Large stockpiles of the material can be a major fire risk due to their supporting oxidation, and may also detonate, as happened in the Texas City disaster of 1947, which led to major changes in the regulations for storage and handling.Two major classes of incidents resulting in explosions are