Aqueous Film-Forming Foam (AFFF) is a type of firefighting foam used to suppress flammable liquid fires, such as those involving petroleum products. It works by creating a film that spreads over the surface of the liquid, cutting off the oxygen supply and preventing the fire from reigniting. AFFF is commonly used by fire departments and in industrial settings where flammable liquids are present. AFFF contains a mixture of water, foam concentrate, and various chemicals that help it form a stable foam. While effective in firefighting, some of these chemicals, particularly per- and polyfluoroalkyl substances (PFAS), have raised environmental and health concerns due to their persistence in the environment and potential harmful effects.