Montreal Protocol

THE MONTREAL PROTOCOL is an international treaty designed to protect the ozone layer by phasing out the production of a number substance (such as CFCs—Chlorofluoro compounds) believed to be responsible for ozone depletion. In the late 1920s, chemicals called chloroflourocarbons (cloro-floro-carbons) or CFCs, were invented. These chemicals were not poisonous and did not harm fabrics, plants, or people. Companies thought they were great products and used them in refrigerators, air conditioners, styrofoam packaging, and spray cans. From the 1920s to the 1970s, billions of CFC molecules were released into the air.

In the 1970s, scientists began to wonder what happened to all the CFCs after they had been in the air for a while. Scientists eventually learned that CFCs could float past the troposphere (troposphere is ...