Following the discovery of the Antarctic ozone hole in late 1985, governments recognized the need for stronger measures to reduce the production and consumption of a number of CFCs and several Halons. The Montreal Protocol on Substances that Deplete the Ozone Layer was adopted onSeptember 16, 1987, at the Headquarters of the International Civil Aviation Organization in Montreal. The Protocol came into force on January 1, 1989, when it was ratified by 29 countries and the EEC. Since then several other countries have ratified it.
The Protocol was designed so that the phase out schedules could be revised on the basis of periodic scientific and technological assessments. Following such assessments, the Protocol was adjusted to accelerate the phase out schedules. It has also been amended to introduce other kinds of control measures and to add new controlled substances to the list.