1958 - Environment

Environment

U.S. scientists begin testing Earth's radiation shield of ozone to discover what effects if any have been caused by atmospheric testing of nuclear weapons and by the growing number of high-altitude flights by military and commercial jet aircraft. Ozone is an unstable form of oxygen containing three atoms instead of the usual two and serves as a barrier at altitudes of 50,000 to 135,000 feet against undue exposure to the sun's ultraviolet rays, which can cause human skin cancer. The ozone layers will be found to increase in the next 13 years, but will then begin to shrink, possibly as a result of being broken up by chlorine gas released from freon gas by ultraviolet rays in the atmosphere at altitudes of 12 to 15 miles (see Freon 12 refrigerant, 1931; plastic aerosol valve, 1953). Nearly a million tons of freon will be released into the atmosphere each year by the 1970s, mostly from aerosol cans, and environmentalists will suggest the possibility that the Earth's ozone layer is being depleted (see Crutzen, 1970).

U.S. Atomic Energy Commission physicist Willard Libby says the United States is the "hottest place in the world" in terms of radioactivity largely as a result of fallout from recent Soviet and British nuclear tests in the atmosphere (see Libby, 1947).