When they were first synthesized in the late 1920s, chlorofluorocarbons (CFCs % for short) seemed too good to be true. These remarkable chemicals, consisting of chlorine, fluorine and carbon atoms, are nontoxic and inert, meaning they do not combine easily with other substances. Because they vaporize at low temperatures, CFCs are perfect as coolants in refrigerators and propellant gases for spray cans. Since CFCs are good insulators, they are standard ingredients in plastic-foam materials like Styrofoam. Best of all, the most commonly used CFCs are simple, and therefore cheap, to manufacture.
There is only one problem. When they escape into the...