In 1981, United Nations Environment Programme (UNEP) established a regulatory and technical committee responsible for drafting principles of ozone protection and this arrived at the introduction of an international treaty called "The Vienna Convention for the Protection of the Ozone Layer".
The Vienna Convention contains commitments of the Parties to co-operate in the research, systematic observations and information exchange on the ODSs production, release and control in accordance with the provisions of this Convention. Although, the Vienna Convention doesn't comprise of obligations for phaseout of ODSs production and utilization, it is the Convention of historical important which is accepted at the world stage on its approach of intergovernmental negotiations and agreed also by all countries in addressing environmental issues. The Vienna Convention has officially been adopted in March 1985, with preliminary 28 countries ratifying the Convention.
The Montreal Protocol on Substances that Deplete the Ozone Layer
After 2 months of the introduction of the Vienna Convention, a team of English scientists led by Dr. Joe Farman published an article relating to their survey of ozone layer at Antarctica. The article revealed a very substantial declination of ozone in spring and a hole in the ozone layer over Antarctica. In Fact, this so called "Ozone Hole" had been discovered before by a US's satellite since 1980, but misunderstood that this accidental finding was just an error of equipment. Although the cause of ozone hole was not exactly identified at that time, CFCs were deemed as the first suspect.
This discovery by Dr. Farman's team stimulated UNEP, which acts as intermediary agency of environment, to boost up intergovernmental negotiations under the Vienna Convention to define requirements and approaches for eliminating the depletion of ozone. This attempt brought to a rapid accomplishment. On 16 September 1987, 47 countries ratified an international pact at Montreal, Canada and called this pact "the Montreal Protocol on Substances that Deplete the Ozone Layer". As a commemoration of ratification of the Montreal Protocol, UNEP proclaimed 16 September the international ozone day and requested all Parties to implement ozone preservation activities.