In 1987, the “Montreal Protocol on Substances that Deplete the Ozone Layer” was signed, agreeing to phase out by 2000, the production and consumption of man-made compounds known to deplete ozone in the stratosphere. Subsequent meetings (1990-97) refined and amended the protocol. Because of their relatively high ozone-depletion potential, in addition to chlorofluorocarbons (CFCs), other man-made compounds—carbon tetrachloride, methyl chloroform, and halons—were the first targets for phaseout. Now, the U.S. Clean Air Act, for example, bans the release of ozone-depleting refrigerants during the maintenance or disposal of air conditioners and other refrigeration equipment.«