Dissociation is slow enough so that these compounds can diffuse down to the troposphere, where they react with water vapor and are removed in rain. Bromine radicals react like chlorine radicals to remove ozone from the stratosphere and sometimes react in concert with chlorine. Ozone is vital to human and animal survival because it is responsible for the absorption of the sun's ultraviolet light. Without this protection, blindness and skin cancers could result from penetrating ultraviolet light. A 1992 amendment to the treaty called for the end of CFC production in industrial countries by 1996, and by 1993 CFC emissions had dropped dramatically.
Halons are organic compounds that are similar to CFCs.
They contain carbon, fluorine, and bromine and may contain chlorine. Halons have been used primarily as propellants in fire extinguishers. Because of their bromine content they are even more destructive to ozone than CFCs, and an amendment to the Montreal Protocol banned their use by 1994. HCFCs consist of carbon, hydrogen, chlorine and fluorine. HFCs are organic compounds that contain hydrogen, carbon and fluorine.