Ozone is a molecule consisting of three oxygen atoms.  Ozone is found in significant quantities in the troposphere (0-15km) and the stratosphere (15-50km).  The “ozone layer” is the relatively high concentration of ozone 20 km thick centered at approximately 25km.  One of the most common and important reactions occurs ultraviolet radiation (<310nm) strikes an ozone molecule; the radiation is absorbed while the molecule is broken down into diatomic and monatomic oxygen (O2 and O).  These molecules are then able to recombine, combine with others, to form new ozone and absorb more ultraviolet radiation.[i]   

            Ultraviolet radiation is classified, based on wavelength, into three different types: UVA, UVB and UVC.  The latter two are important concerns for ozone depletion.  UVC is nearly completely absorbed by the ozone layer while the amount of UVB incident on the earth’s surface is significantly reduced.  Without the ozone layer, serious health effects and disruption of ecosystems would occur.

            The basis of ozone depletion is primarily based on the interference of normal atmospheric chemistry.  A catalytic body (Cl, Br, NOx and others) combines with ozone and then with monatomic oxygen: the result is that an ozone molecule and monatomic oxygen have formed to oxygen molecules while the catalytic body is free to repeat the process.[ii]  This process was first theorized by Professor Crutzen in 1970; the main source of catalytic bodies was NOx from super-sonic travel (SST).  The role of man-made chemicals (chlorofluorocarbons) was first proposed by Professors Rowland and Molina in 1974.[iii]

            In 1972, at the Stockholm Conference on the Human Environment, the United Nations (UN) formed the United Nations Environment Programme (UNEP).[iv]  UNEP was established to be the environmental conscience of the United Nations system.[v]  In 1976, UNEP developed the Outer Limits Subprogramme (OLS); their mission was to determine what part of nature man was altering beyond reversible and acceptable limits.[vi]  The Governing Council decided that the Molina-Rowland hypothesis on the destruction of ozone merited further inquiry.[vii]  

            In 1977, UNEP convened an International Conference of Experts on the Ozone Layer.  The main accomplishment of the Conference was the World Plan of Action on the Ozone Layer.  The central tenet of the Plan was an encouragement of research into atmospheric processes that control the concentration of ozone in the stratosphere and its modification by anthropogenic sources.[viii]

            In order to facilitate the Plan, UNEP acted as a coordinator; responsibilities were delegated to the specialized agencies of the UN.  The World Meteorological Organization (WMO) was assigned to monitor atmospheric constituents and research processes. The Food and Agriculture Organization (FAO) was to assess the effects of ultra-violet radiation on plants and ecosystems.  The World Health Organization (WHO) was to advise on the risks to human health.  To assist in the organization of these efforts the Coordinating Committee on the Ozone Layer (CCOL) was formed.[ix]

            The CCOL convened for the first time in 1978.  With the exception of the WMO, the other organizations declined to participate.  They either gave the issues low priority or discounted the risks as insignificant.  UNEP invited non-governmental organizations that had supported the developing UNEP program, notably the Chemical Manufacturers Association (CMA) and the International Council of Scientific Unions (ICSU), to participate.[x]

            During the next eight years, the CCOL convened on a nearly annual basis.  At these meetings, the committee produced an assessment of ozone layer modification and its impact based on the most recent research results obtained by its members.  An ozone depletion forecast was also given.  Because the science was still in its infancy the forecast fluctuated from 15% depletion one year, to less than 5% the next.  This uncertainty tended to unsettle confidence in the scientific community’s ability to provide reliable information on ozone depletion.[xi]

            Despite this uncertainty, the Molina and Rowland hypothesis remained viable.  Governments reluctantly worked towards a global agreement for the protection of the ozone layer.  In March 1985, the Vienna Convention for the Protection of the Ozone Layer[xii] was adopted.  The Vienna Convention was a framework agreement; further specific regulatory protocols would have to be developed to protect the ozone layer.

            In May 1985, British researchers published an astonishing finding: there was dramatic ozone depletion above Antarctica, more severe than anyone had predicted.[xiii]  This finding, verified by other scientists, provided a political catalyst to protect the ozone layer.   Several meetings were held in rapid succession.  The result was the adoption of the Montreal Protocol on Substances that Deplete the Ozone Layer[xiv] in September 1987.[xv]  

            The Montreal Protocol was ratified and entered into force on January 1, 1989.[xvi]  The protocol was a first in environmental treaties: the problems of ozone depletion were still in the future yet countries made efforts to obviate their occurrence.  The protocol is relatively straightforward.  There are specific measures and timetables for reducing the production and consumption of ozone-depleting substances.  In Annex A, the protocol divides the controlled substances into two groups: Group I (chlorofluorocarbons) and Group II (the halons).  The protocol also makes a distinction between developed and developing countries.

The distinction of countries is made in Article 5, which is the label given to qualified developing countries.  To qualify as an Article 5 country, a party must be a developing country and consume less than 300 grams per capita of the controlled substances on the date of the entry into force of the protocol.  The Article 5 country is allowed to delay the reductions required of developed countries for ten years; however, the Article 5 country is not allowed to exceed the 300g per capita consumption during the extension.[xvii]

Article 2 of the protocol contains the provisions for determining the reductions of the controlled substances.  Under the protocol, developed countries must freeze their production and consumption of Group I compounds at 1986 levels beginning seven months after the protocol enters into force.  Group II compounds will also be frozen at 1986 levels thirty-seven months after entry into force.  From July 1, 1993 to June 30, 1994 Group I compounds consumption must be reduced to 80% of the 1986 levels.  The consumption must be further lowered to 50% of 1986 levels by July 1, 1998 to June 30, 1999.  The protocol does allow for some additional production (above the proscribed reductions) to facilitate the closings of manufacturing plants in developed countries or for export to Article 5 countries.[xviii]

            The protocol also contains provisions to enhance its effectiveness of the specified reductions.  Each party, within one year of the entry into force, is required to ban the import of controlled substances from any State not party to the protocol; this ban applies to Article 5 countries starting January 1, 1993.  Other exclusionary provisions contained in the protocol include banning (or studying the feasibility of banning) the importation of products made with, or containing, controlled substances manufactured by non-parties and discouraging the exportation of controlled substance technology to non-parties.[xix]  The protocol also contained an explicit provision providing for the assessment and review of control measures. The parties, beginning in 1990, are required to assess the control measures based on available scientific, environmental, technical and economic information. [xx]

            The parties began to implement measures to strengthen the protection of the ozone layer.  Since 1987, the protocol has been amended or adjusted four times, however not all of the amendments have been ratified by the parties to the Montreal Protocol.  The amendments have expanded the definition of controlled substances from 8 to 95.  The reduction schedules were also accelerated in both time and magnitude, requiring the complete phase-out of the controlled substances.[xxi]



[i] Brekke, Physics of the Upper Polar Atmosphere, Sec 3.12, (1997).

[ii] Id. at (3.13).

[iii] Nature, 249, 810-12 (1974).

[iv] http://www.unep.org/unep/about.htm

[v] Id.

[vi] Usher, Ch. 11, p.119, Ozone Depletion: Health and Environmental Consequences, Russell Jones and Wigley (Eds.)(1989).

[vii] Id.

[viii] Id.

[ix] Id.

[x] Id. at 120.

[xi] Id.

[xiii] Farman, Nature, 315, 207-10 (1985).   Link to paper.

[xv] Usher, p.125.

[xvi] http://www.unep.ch/ozone/ratif.htm

[xvii] Montreal Protocol, Article 5, Section 1 (1987).

[xviii] Id., Article 2.

[xix] Id., Article 4.

[xx] Id., Article 6.

[xxi] Montreal Protocol (1997).