(hydroxy-phosphonooxy-phosphoryl)oxyphosphonic acid is a major type of phosphorus-based flame retardant, used in fire extinguishing agents, flame-retardant coatings, and flame-retardant polymer materials. It is an upgraded replacement for halogenated flame retardants. Halogenated flame retardants and their flame-retardant polymer materials decompose at high temperatures, producing toxic fumes such as polybrominated dibenzofurans and polybrominated dibenzofurans. 80% of the hazards of fires come from the inhalation of excessive dense smoke; this is a fatal flaw of halogenated flame retardants. The European Community has proposed restricting the use of these flame retardants and will gradually phase them out. Although ammonium polyphosphate's flame-retardant efficiency is not as high as halogenated flame retardants, it does not produce toxic substances during combustion, has good thermal stability, and is smokeless and non-toxic. Based on these factors, ammonium polyphosphate flame retardants have experienced rapid growth.
