Engineering students at George Mason University discovered a way to extinguish fire using sound waves. The low frequency pressure waves created by their device can quickly drown out the oxygen supply to a fire. No oxygen means no fire. Clever! They are hoping to apply their discovery to drones which can enter dangerous environments such as confined spaces and spaces with limited access to water such as forest fires. Indeed this may eliminate the need for the use of fire suppressant foam (aqueous film forming foam (AFFF)) some of which contain fluoridated surfactants such as perfluorooctanesulfonic acid (PFOS). PFOS while considered extremely effective as a fire suppressing agent due to it's low surface tension and positive spreading coefficient, is considered a persistent, bioaccumulative, and toxic pollutant.
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