History of chlorofluorocarbons (CFCs) as refrigerants
Refrigerators from the late 1800s until 1929 used the toxic gases, ammonia (NH3), methyl chloride (CH3Cl), and sulfur dioxide (SO2), as refrigerants. Several fatal accidents occurred in the 1920s because of methyl chloride leakage from refrigerators. A collaborative effort began between three American corporations, Frigidaire, General Motors and DuPont to search for a less dangerous method of refrigeration.
In 1928, Thomas Midgley, Jr., in cooperation with Albert Leon Henne and Robert Reed McNary, invented a "miracle compound" called Freon, as a substitute for the toxic gaseous refrigerants (ammonia, butane, methyl chloride (or bromide), sulfur dioxide) in use at that time. (1) Freon represents several different chlorofluorocarbons, or CFCs, which are used in commerce and industry. The CFCs are a group of aliphatic organic compounds containing the elements carbon and fluorine, and, in many cases, other halogens (especially chlorine) and hydrogen. Freons are colorless, odorless, nonflammable, noncorrosive gases or liquids. Because Freon is non-toxic, it eliminated the danger posed by refrigerator leaks. In just a few years, compressor refrigerators using Freon became the standard for almost all-home kitchens. In 1930, Thomas Midgley held a demonstration of the physical properties of Freon for the American Chemical Society by inhaling a lung-full of the new wonder gas and breathing it out onto a candle flame, which was extinguished, thus showing the gas's non-toxicity and non-flammable properties. (2) However only decades later, in 1973, Prof. James Lovelock reported finding trace amounts of refrigerant gases in the atmosphere. (3) In 1974, Sherwood Rowland and Mario Molina predicted that chlorofluorocarbon refrigerant gases would reach the high stratosphere and there damage the protective mantle of the oxygen allotrope, ozone. (4) In 1985 the "ozone hole" over the Antarctic had been discovered and in 1990 Rowland and Molina's prediction was proved correct. (5)