On 13 January 1982, the Secretariat of the United Nations Environment Programme published a document for the ad hoc working group (UNEP/WG.69/8) entitled «Some Observations on the Development of a Global Framework Convention for the Protection of the Stratospheric Ozone Layer.» In particular, the document referred to the relevant recommendations and contributions of the ad hoc meeting of the government`s senior environmental law official (October 28 to November 6, 1981) (UNEP/WG.69/8, para. 7, 8, 36 and 37), of the UNEP Ozone Layer Coordination Committee (UNEP/WG.69/8, 8 Paragraphs 3, 8, 15 and 33), as well as the documents submitted by the delegations of Finland, Sweden, Switzerland and Norway (UNEP/69/8, para. 9, 36 and 42), including the draft International Convention for the Protection of the Stratospheric Ozone Layer (UNEP/EEC.69/3). At its ninth session, the Executive Board of the United Nations Environment Programme adopted Decision 9/13B of 26 May 1981, which, recognizing the opportunity to initiate work towards the development of a comprehensive framework convention, would include monitoring, scientific research and the development of the best available and economically viable technologies to limit and gradually reduce emissions of ozone-depleting substances, as well as the development of appropriate strategies and policies, decided to launch work towards the development of such a convention. To this end, the Governing Council has also decided to establish an ad hoc working group of legal and technical experts to develop a global framework convention for the protection of the ozone layer, to report to the Board of Governors, through the Executive Director, on the progress of its work (see The Governing Council report, A/36/25). Montreal Protocol, Montreal`s official protocol on ozone-depleting substances, an international treaty adopted in Montreal on September 16, 1987, to regulate the production and use of chemicals that contribute to the depletion of the earth`s ozone layer. Originally signed by 46 countries, the treaty now has nearly 200 signatories. 2012 marked the 25th anniversary of the signing of the Montreal Protocol. As a result, the Montreal Protocol Community organized a series of national, regional and international celebrations to showcase the considerable success it has had so far and to review future work.  Among its achievements, the Montreal Protocol was the first international treaty to meet a global environmental regulatory challenge; the first, which takes up the «precautionary principle» in its development for science-based policy-making; The first treaty, in which independent experts in atmospheric, environmental, chemical technology and economics reported directly to the parties, without treatment or censorship, under the standards of professionalism, mutual verification and respect; the first, which provides for national differences in accountability and financial capacity, in response to the creation of a multilateral technology transfer fund; The first MEA, which imposes strict reporting, trade and chemical requirements for both developed and developing countries; and the first treaty, with a financial mechanism, democratically managed by an executive council also representing industrialized and developing countries.  The Kigali amendment to the Montreal Protocol came into effect on January 1, 2019.  Under the Kigali amendment, countries have promised to reduce the use of hydrofluorocarbons (HFCs) by more than 80% over the next 30 years.  As of 27 December 2018, 65 countries had ratified the amendment.
 The Montreal Protocol on Ozone Depleting Substances is a 1987 international agreement.