AFFF stands for aqueous film-forming foam. It is used as a fire suppressant, and functions by cooling the fire and coating the fuel behind the fire. It creates a film between the fuel and oxygen to prevent further combustion.
While AFFFs manufactured now do not contain these chemicals, existing stockpiles continue to be used. Even where they are no longer used, PFOA and PFOS continue to pose significant health risks to humans, animals and the environment as they are stable and can remain toxic for many years. In many areas where the toxic AFFFs were used, PFOS and PFOA have contaminated the groundwater and soil.