The Montreal Protocol is a 1987 treaty between U.N.-recognized nations to phase out the use of ozone-depleting chemicals, such as chlorofluorocarbons, carbon tetrachloride and methyl chloroform. The treaty was then amended in 1990 and 1992.
Ozone is a compound consisting of three atoms of oxygen bonded together. Most of these molecules exist as a layer in the stratosphere blanketing the Earth. The ozone layer absorbs much of the harmful ultraviolet radiation coming from the sun, especially UV-B. In addition to its protective function, ozone insulates the Earth, keeping heat from escaping into space.
The use of ozone-depleting chemicals destroys ozone molecules. Because of scientific evidence pointing to the thinning of certain parts of the ozone layer around the world, nations of the world banded together to try to preserve the ozone layer through the Montreal Protocol.