Aerosols expert witnesses may write reports and opine on aerosol sprays, airborne solid particles, and household chemicals. The National Aerosol Association describes the history of aerosols:
The first use for an aerosol package arose during World War II, but the idea of using low-pressure liquefied gas to atomize droplets of liquid in the air was developed in 1924. Canisters filled with insecticide and propellants were used to protect U.S. servicemen from insects carrying diseases such as malaria. Shortly after the war, Robert Abplanalp, founder of Precision Valve Corporation (PVC), invented the first mass-produced aerosol valve. The patent was filed in September 1949 and was issued on March 17, 1953. From that invention, the aerosol industry quickly developed in the United States and around the world.