Ministry of Environment, Forest and Climate Change. 12-September, 2008 16:7 IST
Ozone Layer – Preserving Life on the Planet

The entire world will celebrate 21st World Ozone Day on 16th of this month. Theme for the year 2008 is “Montreal Protocol - Global partnership for global benefits". Nations considered the urgent need to preserve the ozone layer, which filters sunlight and prevents the adverse effects of ultraviolet radiation reaching the Earth's surface, thereby preserving life on the planet.

The issue of ozone depletion was first discussed by the Governing Council of the United Nations Environment Programme (UNEP) in 1976. A meeting of experts on the ozone layer was convened in 1977, after which UNEP and the World Meteorological Organization (WMO) set up the Coordinating Committee of the Ozone Layer (CCOL) to periodically assess ozone depletion. Intergovernmental negotiations for an international agreement to phase out ozone-depleting substances started in 1981 and concluded with the adoption of the Vienna Convention for the Protection of the Ozone Layer in March 1985. The 1985 Vienna Convention encouraged intergovernmental cooperation on research, systematic observation of the ozone layer, monitoring of CFC production and the exchange of information. The parties are committed as per the Convention to take general measures to protect human health and the environment against human activities that modify the ozone layer. The Vienna Convention is a framework agreement and does not contain legally binding controls or targets. The Montreal Protocol on Substances that Deplete the Ozone Layer was adopted in September 1987. Highlighting the importance of the implementation of the Montreal Protocol on Substances that Deplete the Ozone Layer, to find out ozone-friendly products and to create awareness, It was proclaimed on September 16, the International Day for the Preservation of the Ozone Layer. All Member States are invited to devote this special day to promote, at the national level, of concrete activities in accordance with the objectives and goals of the Montreal Protocol and its Amendment. Governments are not legally bound until they ratify the Protocol as well as the Amendments. Unfortunately, while most governments have ratified the Protocol, ratification of the amendments and their stronger control measures lag behind. As of today, the Ozone Agreements had been signed by 193 nations.

            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 (CFC-11, 12, 113, 114, and 115) and several Halons (1211, 1301, 2402). 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 in London in 1990, Copenhagen in 1992, Vienna in 1995, Montreal in 1997, and Beijing in 1999. It has also been amended to introduce other kinds of control measures and to add new controlled substances to the list; the 1990 London Amendment included additional CFCs (CFC-13, 111, 112, 211, 212, 213, 214, 215, 216, 217) and two solvents (carbon tetrachloride and methyl chloroform), while the 1992 Copenhagen Amendment added methyl bromide, HBFCs and HCFCs. The Montreal Amendment of 1997 finalized the schedules for phasing out methyl bromide. The Beijing Amendment of 1999 included Bromochloromethane for immediate phase out; it also introduced production controls on HCFCs as well as controls on trade with non-Parties.

The Ozone Layer

Ozone molecules (O3) consist of three oxygen atoms. This poisonous gas is extremely rare in the atmosphere, representing just three out of every 10 million molecules. Ninety per cent of ozone exists in the upper atmosphere, or stratosphere, between 10 and 50 km (6-30 miles) above the earth. Ozone at ground-level, at the bottom of the troposphere, is a harmful pollutant resulting from automobile exhausts and other sources.

The ozone layer absorbs most of the harmful ultraviolet-B radiation from the sun. It also completely screens out lethal UV-C radiation. The ozone shield is thus essential to life as we know it. Depleting the ozone layer allows more UV-B to reach the earth. More UV-B means more melanoma and non-melanoma skin cancers, more eye cataracts, weakened immune systems, reduced plant yields, damage to ocean eco-systems and reduced fishing yields, adverse effects on animals, and more damage to plastics. Scientific concern started in 1970 when Prof. Paul Crutzen pointed out the possibility that nitrogen oxides from fertilizers and supersonic aircraft might deplete the ozone layer. In 1974, Professors F. Sherwood Rowland and Mario J. Molina recognized that when CFCs finally break apart in the atmosphere and release chlorine atoms they cause ozone depletion. Bromine atoms released by halons have the same effect. The three scientists received the Nobel Prize for Chemistry in 1995 for their pioneering work.

The ozone layer over the Antarctic has steadily weakened since measurements started in the early 1980s. The problem is worst over this part of the globe due to the extremely cold atmosphere and the presence of polar stratospheric clouds. The land area under the ozone-depleted atmosphere increased steadily to more than 20 million sq km in the early 1990s and has varied between 20 and 29 million sq. km since then. The area of the ozone hole reached a record 29 million sq. kilometers on 12 September 2000; it extended to 27 million sq. km. in September 2003 and 24 million sq. km in 2004. While no hole has appeared elsewhere, the Arctic spring has seen the ozone layer over the North Pole thin by up to 30%, while the depletion over Europe and other high latitudes has varied between 5% and 30%.

Chemicals and their Phase-Out Schedules

Ninety-six (96) chemicals are presently controlled by the Montreal Protocol, including:

·   Halo-carbons, notably chlorofluorocarbons (CFCs) and Halons. CFCs were discovered in 1928 and were considered wonder gases because they are long-lived, non-toxic, non-corrosive, and non-flammable. They are also versatile and from the 1960s were increasingly used in refrigerators, air conditioners, spray cans, solvents, foams, and other applications. CFC-11 remains in the atmosphere for 50 years, CFC-12 for 102 years, and CFC-115 for 1,700. Halon 1301 is used primarily in fire extinguishers and has an atmospheric lifetime of 65 years.

·   Carbon tetrachloride is used as a solvent and takes about 42 years to break down in the atmosphere.

·   Methyl chloroform (1,1,1-trichloroethane) is also used as a solvent and takes about 5.4 years to break down..

·   Hydrobromofluorocarbons (HBFCs) are not widely used, but they have been included under theProtocol to prevent any new uses.


·   Hydrochlorofluorocarbons (HCFCs) were developed as the first major replacement for CFCs. While much less destructive than CFCs, HCFCs also contribute to ozone depletion. They have an atmospheric lifetime of about 1.4 to 19.5 years.

·   Methyl bromide (CH3Br) is used as a fumigant for high-value crops, pest control, and quarantine treatment of agricultural commodities awaiting export. Total world annual consumption for controlled uses (not including uses for quarantine and pre-shipment) was about 30,000 tonnes in 2004. It takes about 0.7 years to break down..

·   Bromochloromethane (BCM), a new ozone-depleting substance that some companies sought to introduce into the market in 1998, has been targeted by the 1999 Amendment for immediate phase-out to prevent its use.

            India had four major chemicals to phase-out, namely CFCs, CTC, Halons and HCFCs. Out of this Halons were first to be phased out  at the beginning of 2003. CFCs also have been phased out by 1st August, 2008. CTC will be phased out by end of 2009 and HCFCs phasing out process is still going on. The Parties are considering measures to prevent the marketing of new ozone-depleting substances not so far covered by the Protocol.

The phase-out schedule for developed countries regarding Halons, and CFCs, carbon tetrachloride, methyl chloroform, and HBFCs have been completed by 1994 and 1996 respectively. Reduction of methy bromide was carried out by 25% by 1999, 50% by 2001, 70% by 2003, and complete phase out by 2005.HCFCs were also reduced during a period of 35% by 2004, 65% by 2010, 90% by 2015, and 99.5% by 2020, with 0.5% permitted for maintenance purposes only until 2030.  Phase out of   HBFCs by 1996 and phase out of BCM was scheduled immediately.

            Developing countries had a grace period before they must start their phase-out schedules. This reflects the recognition that developed countries are responsible for the bulk of total emissions into the atmosphere and that they have more financial and technological resources for adopting replacements. The developing country schedule was:

·   Phase out HBFCs by 1996 and phase out BCM immediately;

·   Freeze CFCs, Halons and carbon tetrachloride at average 1995-97 levels by 1 July 1999, reduce by 50% by 2005, 85% by 2007, and phase out completely by 2010;

·   Freeze methyl chloroform by 2003 at average 1998-2000 levels, reduce by 30% by 2005 and 70% by 2010, and phase out by 2015;

·   Freeze methyl bromide by 2002 at average 1995-98 levels, reduce by 20% by 2005, and phase out by 2015; and

·   Freeze HCFCs by 2016 at 2015 levels and phase out by 2040.

            The phase-out schedules cover both the production and the consumption of the target substances. However, even after phase out both developed and developing countries are permitted to produce limited quantities in order to meet the essential uses for which no alternatives have yet been identified, e.g. the use of CFCs in metered dose inhalers for asthma. Production is defined as total production minus amounts destroyed or used as chemical feedstock. Consumption is defined as production plus imports minus exports. Trade in recycled and used chemicals is not included in the calculation of consumption in order to encourage recovery, reclamation and recycling.

            Without the Protocol, by the year 2050 ozone depletion would have risen to at least 50% in the northern hemisphere's mid latitudes and 70% in the southern mid latitudes, about 10 times worse than current levels. The result would have been a doubling of UV-B radiation reaching the earth in the northern mid latitudes and a quadrupling in the south. The amount of ozone-depleting chemicals in the atmosphere would have been five times greater. The implications of this would have been horrendous: 19 million more cases of non-melanoma cancer, 1.5 million cases of melanoma cancer, and 130 million more cases of eye cataracts.

            In 1986 the total consumption of CFCs world-wide was about 1.1 million ODP tonnes; by 2004 this had come down to about 70,000 tonnes. (The ODP, or ozone-depleting potential, of a gas is based on comparing its impact on the ozone layer to that of CFC-11.) It has been calculated that without the Montreal Protocol global consumption would have reached about 3 million tonnes in the year 2010 and 8 million tonnes in 2060, resulting in a 50% depletion of the ozone layer by 2035. The bulk of the 1986 total, or about 0.9 million ODP tonnes, was consumed in developed countries, but this figure had declined to about 2,000 tonnes annually in the years 2003 and 2004, including consumption for exemptions approved by the Parties. By 2004, the developing countries had reduced their CFC consumption by about 60% from their maximum consumption in the mid-1990s.

The Global Environment Facility (GEF) was established by the world community to help developing countries address ozone depletion, climate change, biodiversity and international waters. The GEF also supports projects and activities for phasing-out ozone-depleting substances in countries with economies in transition, as most of these Central and East European countries are not eligible for Multilateral Fund assistance. Between 1996 and 2000, GEF approved over $160 million to assist the following 17 countries:

Azerbaijan, Belarus, Bulgaria, Czech Republic, Estonia, Hungary, Kazakhstan, Latvia, Lithuania, Poland, Russian Federation, Slovakia, Slovenia, Tajikistan, Turkmenistan, Ukraine and Uzbekistan. Additional funds of $60 million have been ear-marked by GEF to assist these countries with the phase-out of HCFCs and Methyl Bromide.

            Scientists predict that ozone depletion will reach its worst point during the next few years and then gradually reverse until the ozone layer returns to normal around 2050, assuming that the Montreal Protocol is fully implemented. The ozone layer is currently in its most vulnerable state. Despite declining CFC emissions, stratospheric concentrations are still increasing (although they are declining in the lower atmosphere) because long-lived CFCs emitted in earlier years continue to rise to the stratosphere. The atmospheric abundance of certain CFCs (notably CFC-11 and CFC-113), carbon tetrachloride, and methyl chloroform is declining. The abundance of most of the halons continues to increase. Concentrations of HCFCs and HFCs (see below) are, of course, increasing, since they are used as substitutes for the CFCs that are being phased out. The success of ozone protection has been possible because science and industry have been able to develop and commercialize alternatives to ozone-depleting chemicals.

The Montreal Protocol offers many lessons that could be applied to solving other global environmental issues:

·   Adhere to the "precautionary approach" because waiting for complete scientific proof can delay action to the point where the damage will become irreversible.

·   Send consistent and credible signals to industry (e.g. by adopting legally binding phase-out schedules) so that they have an incentive to develop new and cost-effective alternative technologies.

·   Ensure that improved scientific understanding can be incorporated quickly into decisions about the provisions of a treaty.

·   Promote universal participation by recognizing the "common but differentiated responsibility" of developing and developed countries and ensuring the necessary financial and technological support to developing countries.

·   Control measures should be based on an integrated assessment of science, economics, and technology. (PIB Features)

*Deputy Director(M & C), PIB, New Delhi



(Release ID :42725)