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The findings and conclusions from the intensive and extensive ozone research over the past few years have several major implications as input to public policy regarding restrictions on man‑made substances that lead to stratospheric ozone depletion:

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‑ The scientific basis for the 1987 Montreal Protocol on Substances that Deplete the ozone layer was the theoretical prediction that, should CFC and halon abundances continue to grow for the next few decades, there would eventually be substantial ozone layer depletion. The research of the last few years has demonstrated that actual ozone loss due to man‑made chlorine (i.e., CFCs) and bromine has already occurred, i.e., the Antarctic ozone hole.
‑ Even if the control measures of the Montreal Protocol were to be implemented by all nations, today's atmospheric abundance of chlorine (about 3 parts per billion by volume (ppbv)) will at least double to triple during the next century. If the atmospheric abundance of chlorine reaches about 9 ppbv by about 2050, ozone depletions of 0‑4 per cent in the tropics and 4 ‑ 12 per cent at high latitudes would be predicted, even without including the effects of heterogeneous chemical processes known to occur in polar regions, which may further increase the magnitude of the predicted ozone depletion.
‑ The surface‑induced, PSC‑induced chemical reactions which cause the ozone depletion in Antarctica and also occur in the Arctic, represent additional ozone‑depleting processes that were not included in the stratospheric ozone assessment models used to guide the Montreal Protocol. Recent laboratory studies suggest that similar reactions involving chlorine compounds may occur on sulfate particles present at lower latitudes, which could be particularly important immediately after a volcanic eruption. Hence, future global ozone layer depletions could well be larger than originally predicted.
‑ Large‑scale ozone depletions in Antarctica appear to have started in the late 1970s and were initiated by atmospheric chlorine abundance of about 1.5‑2 ppbv, compared to today's level of about 3 ppbv. To return the Antarctic ozone layer to levels of the pre‑1970s, and hence to avoid the possible ozone dilution effect that the Antarctic ozone hole could have at other latitudes, one of a limited number of approaches to reduce the atmospheric abundance of chlorine and bromine is a complete elimination of emissions of all fully halogenated CFCs, halons, carbon tetrachloride, and methyl chloroform, as well as careful considerations of the HCFC substitutes. Otherwise, the Antarctic ozone hole Is expected to recur seasonally, provided the present meteorological conditions continue.
2.2 Environmental Effects
With depletion of the ozone layer, the intensity of the UV‑B radiation reaching the ground increases and the wavelength composition is shifted to shorter wavelengths. Most effects of ultraviolet radiation depend strongly on the wavelength, with the largest impacts associated with the shorter wavelengths.

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UV‑B radiation is known to have a multitude of effects on humans, animals, plants, and materials. Most of these effects are damaging. The knowledge required for quantitative predictions of the effects, however, is available only for a few of these damages. Even with the present limited level of quantification, it is clear that some of these effects could pose significant environmental threats.
The potential effects of increased levels of UV‑B radiation due to ozone depletion include the following:
Human Health
Exposure to increased UV‑B radiation can cause suppression of the body's immune system, which might lead to an increase in the occurrence or severity of infectious diseases such as herpes, leishmaniasis and malaria and a possible decrease in the effectiveness of vaccination programmes.
Enhanced levels of UV‑B radiation can lead to increased damage to the eyes, especially cataracts the incidence of which is expected to increase by 0.6 per cent per 1 per cent total column ozone depletion. Therefore, each 1 per cent total column ozone depletion is, in the long run, expected to lead to a worldwide increase of 100,000 blind persons due to UV‑B induced cataracts, other things being equal (e.g. population, age distribution, 'availability of medical care, etc.). Damage to the eyes and possible increases in incidence or severity of infectious diseases would be serious, particularly where these diseases occur most, even now.
Non‑melanoma skin cancer will increase with any long‑term increase of the surface UV‑B radiation, without a threshold value. Every 1 per cent decrease of total column ozone is predicted to lead to a 3 per cent rise of the incidence of non‑melanoma skin cancer; other things being equal ‑ e.g. the exposure of people to sunlight. There is concern that an increase of the more dangerous cutaneous malignant melanoma could also occur. The current incidence of non‑melanoma skin cancer is much higher than for melanoma skin cancer, but the current annual number of deaths attributable to the two types of cancer is about the same. Increase of skin cancer would mainly affect people with little protective pigment in their skin, i.e. light‑skinned people.
Terrestrial Plants
Of the plant species investigated (approximately 80 varieties of 12 species), about half were found to be sensitive to enhanced UV‑B radiation, the impact being that plants typically have reduced growth and smaller leaves. This sensitivity applies, for instance, for certain in varieties of soybeans and wheat. In some eases, these plants also show changes in their chemical composition, which can affect food quality and the availability of mineral nutrients. Within species, varieties have different UV‑B sensitivities, as is also demonstrated in soybeans. While some varieties of soybeans are not sensitive at all, increased UV‑B reduces food yield by up to 25 per cent in certain economically important varieties, for exposures simulating 25 per cent

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total column ozone depletion. Even small decreases in food production from UV‑B effects on agriculture would significantly affect people in areas where food shortages occur even now. There is an urgent need for development of biotechnology for replacement of sensitive crops.

Aquatic Ecosystems
Increased UV‑B irradiance has been shown to have a negative influence on aquatic organisms, especially small ones such as phytoplankton, zooplankton, larval crabs and shrimp, and juvenile fish. Because many of these small organisms are at the base of the marine food web, increased UV‑B exposure may have a negative influence on the productivity of fisheries.
Increased exposure to UV‑B radiation could lead to decreased nitrogen assimilation by prokaryotic microorganisms and, thereby, to a possible nitrogen deficiency for rice paddies. The potential loss in yield has not yet been quantified.
Since phytoplankton fix carbon dioxide in photosynthesis, damage to phytoplankton by increased UV‑B radiation would indirectly contribute to the radiative forcing of predicted global warming induced by greenhouse gases.
Tropospheric Air Quality
Enhanced levels of surface UV radiation could cause increased atmospheric abundances of several chemically reactive compounds, notably ozone, hydrogen peroxide, and acids. It is also possible that the atmospheric abundance of particulates could be enhanced. This would aggravate the environmental pollution problems already present in many urban and rural areas and increase the negative influences of air pollution on human health and agricultural productivity, assuming that existing pollution controls are not strengthened.
Materials Damage
Exposure to UV radiation is a significant cause of degradation of many materials, particularly plastics that are used outdoors. The impact is mainly economic. The increased damage will be most severe in tropical locations, where the degradation may be enhanced by high ambient temperatures and sunshine levels.
Global Warming
The present atmospheric abundance of controlled substances contribute 20 per cent to 25 per cent of the anthropogenic radiative forcing of global warming.

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Key Areas of Uncertainty
The key areas of uncertainty are in the following areas:
‑ Quantification of the primary effects on food production and quality, on forestry, and natural ecosystems.
‑ Clarification and quantification of influences on human health, especially the immune system, and occurrences of melanomas and cataracts.
‑ Effects on biota of the enhanced UV radiation during the Antarctic springtime ozone depletion.
2.3 Technology Review
The goal of the Technology Assessment Panel was to determine and quantify the technical feasibility of reductions of ozone depleting substances.
Technical feasibility in this respect is defined as the possibility to

provide substitutes or alternative processes without substantially affecting

properties. performance and reliability of goods and services from a technical

and environmental point of view. I

Taking into account the current state of the technological development, it is technically feasible to phase down the production and consumption of the five CFCs controlled under the Montreal Protocol, as well as carbontetrachloride, by at least 95 per cent by the year 2000.
The remaining demand after the year 2000 would be from refrigeration and air conditioning (principally automotive) systems that were designed to use CFCs and are still in service (and not amenable to near "drop in" substitutes) and minor uses. These remaining uses are expected to be eliminated within 5‑10 years thereafter. Figure 1 shows the technically feasible phase‑down projections for any year for each of the major use categories.
It is assumed that HFCs and HCFCs currently under testing will be environmentally acceptable and commercially available. The time scale for full commercialization for some chemicals remain uncertain at this time but chemical manufacturers are working on many chemical substitutes. Three Programmes for Alternative Fluorocarbon Toxicity Testing (PAFT I, II and III) and the programme AFEAS on the environmental acceptability have been defined; the results will be published as soon as they are available in open literature. Final results of testing of these substitute chemicals will not be available for three or more years.
The key conclusions from the technology assessment are:
‑ The refrigeration, air conditioning, and heat pump sector represents 25 per cent of global consumption of the controlled CFCs. Globally, under 8 per cent is used for food preservation and developing

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countries' share of this is less than one quarter. Domestic refrigeration worldwide accounts for 1 per cent. Evidence suggest that for developing countries, a 30 per cent annual growth rate in the manufacture of domestic refrigerators can be assumed. Thus demand from developing countries (including India and the Peoples' Republic of China) for CFC‑12 for refrigerators only, will at the year 2000 represent less than 2 per cent annually of the global 1986 CFC consumption level. The assessment also assumes recycling and reuse of 60 per cent of existing CFC refrigeration fluids in the year 2000.
It is necessary to distinguish between new and existing equipment. New designs using alternative refrigerants are possible in many, but not all subsectors now, but existing equipment will have to be upgraded and replaced slowly, with full substitution taking up to 15‑20 years. One major problem is that automotive air conditioning represents a large use of CFCs and some automobiles produced before a switch to new environmentally acceptable refrigerants will be in use well after the year 2000.
‑ 25 per cent of the world's CFCs are used in foam production. It is technically feasible to reduce consumption by 60‑70 per cent by 1993 with a phase out of at least 95 per cent by 1995. These reductions are dependent to a large degree on the availability of new HCFCs.

CFC‑113 solvent use in electronic, precision, metal, and dry cleaning represents about 16 per cent of the global consumption of the controlled CFCs. There is no single universal substitute for all CFC‑113 solvent uses, but rather a myriad of options. The most predominant use is in the electronics subsector. All CFC‑113 solvent uses can be phased out by the year 2000. The CFC‑113 phase out is only partially dependent on the availability of HCFCs, due to the large variety of non‑HCFC alternatives including: product and process substitutes, water cleaning, hydrocarbons (e.g., terpenes, alcohol, and white spirits), cleaning processes that do not require the use of solvents, etc.

Sufficient technical options exist now to phase out CFC use as aerosol propellants with the exceptions being some medical products and other minor uses. CFC‑12 use in sterilization can be substantially reduced using existing alternatives and can be phased out by 1995 in developed countries and somewhat later in developing countries. In food freezing applications, substitution is technically feasible and several techniques are commercially available.
Methyl Chloroform (1,1,1 Trichloroethane) is a widely used all purpose solvent. It has an ozone depletion potential of between .10‑.16 and a lifetime of 6.3 years. Because of its large production, it contributes to current ozone depletion to about the same degree as CFC‑11, CFC‑12 or carbon tetrachloride, since much of the depletion associated with the current production and consumption of these

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longer‑lived gases lies in the future. Substitutes currently exist in each of the three major uses of methyl chloroform: cleaning solvent; adhesives; and aerosols. Reductions of 90‑95 per cent of current usage appear feasible.
‑ Carbon tetrachloride has an Ozone Depletion Potential of 1.0‑1.2. It is primarily used as a feedstock for CFCs, but may also be used for example, as a constituent of pesticides, as a solvent in the manufacture of synthetic rubber and dyes, as a dry cleaning agent and as a grain fumigant. These uses in many countries have been eliminated In recent years due to toxicity concerns. As a result, substitutes currently exist for the majority of its uses.
‑ Based on projections of the chemical industry at the year 2000, HCFCs are estimated to capture up to 30 per cent of the current CFC market. An additional 10 per cent of demand could be captured by HFCs with the remaining 60 per cent of demand satisfied by product and process substitutes. The use of HCFCs and HFCs will be essential in achieving early reductions and eventual phase‑out of CFCs.
‑ There are currently no substitute chemicals with equivalent characteristics to halons. Other fire protection techniques (including carbon dioxide and water sprinkler system) are, however, available in most applications that offer adequate fire protection. In addition, proper fire protection is also dependent on other features, such as detection systems, fire restrictive enclosures, cable and wire insulation, proper construction planning, etc. A timetable for phasing down halon consumption has been discussed by experts in the Review Panel Committee. No consensus was reached on a possible timetable, although the majority of experts felt that conservation practices and the before mentioned protection measures alone are adequate to allow an orderly and complete phaseout by the year 2005. Some believed a reduction of 60 per cent, at the most, was achievable within 5 years with a total phaseout possible if alternative chemicals became available. Others concluded that a reduction schedule was premature until substitutes became available.
‑ Technology is currently available to capture, recycle, and destroy CFCs and halons. However, more cost effective techniques are currently under development.
Since substitutes currently exist for most of their uses, it is technically feasible by the year 2000 to:
‑ Phase down by at least 95 per cent the production and consumption of the five controlled CFCs.
‑ Phase out totally the production and consumption of carbon tetrachloride since this has been possible in many countries.
‑ Phase down by at least 90 per cent the production and consumption of methyl chloroform.

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Reductions for CFCs and methyl chloroform require that substitutes currently available or under development are environmentally acceptable and are made commercially available throughout the world.
Production of all of the substances referred to above would not be restricted for subsequent use as a chemical feedstock.
2.4 Economic Implications
A review of the Protocol measures requires an appraisal of the costs of substitution of CFCS and halons and the benefits of avoiding ozone depletion.
Canada, United States of America, Europe, and Japan account for approximately 80 per cent of the total consumption of controlled chemicals. The per capita consumption in developed economies is in many cases more than ten times the per capita consumption in most developing countries. Economic implications have to be considered in the context of developed and developing economies separately.
Economic/Environmental Benefits of Reduced CFC/halon Use.
Reducing the use of ozone‑depleting substances could have enormous beneficial impacts on human health and the environment in both developed and developing countries. The current state of scientific knowledge makes it very difficult to quantify the magnitude of many of these impacts. Nevertheless, the scientific evidence is mounting that predicted stratospheric ozone depletion will cause increased levels of skin cancers, cataracts, immune suppression, and other human health Impacts, plus additional effects on plants and animals, among others. Many factors associated with proper valuation procedures vary from one region of the world to another and between people alive today and generations to come. These issues make it inherently difficult, if not impossible, to assign a monetary value to the harmful impacts avoided as a result of the reduction in use of ozone‑depleting substances.
This difficulty in economic quantification does not change the basic conclusion of the economics panel that, on a global basis, the monetary value of the benefits of safeguarding the ozone layer is undoubtedly much greater than the costs of CFC and halon reductions. However, developing countries are less able to pay the costs of reducing or phasing out CFCs and halons and may have other, more immediate concerns such as food supply and economic development. Given the fact that a glob ' al CFC reduction is essential for the protection of the ozone layer, diffusion of CFC and balon replacement technology, including recovery and recycling, is necessary and is in the interest of both developed and developing countries alike.
The Costs of Technical Substitution
The costs of reducing or eliminating CFCs and halons depend on a variety of factors including capital costs, research and development costs, operational costs (such as energy and labour costs), and safety and toxicity

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risks. Differences in national development and in the extent of development of CFC and halon producing and consuming industries result in large differences in transition costs for each country. Detailed estimates of the changeover costs cannot at present be made for many options. Consequently, global cost estimates are difficult to make with reasonable accuracy.
The development of options for replacing CFCs and halons is progressing rapidly. As economically feasible safe substitutes become available on a global basis, the current costs of CFC and halon reductions are expected to be reduced.
Most technical options require initial capital investments, but ultimately, some are less expensive to operate or offer improvements in product quality. The first 50 per cent reduction in the global use of CFCs will require modest new capital investment, will incur little or no net cost, will result in some business disruption, and will require very little capital abandonment. This relatively easy step will be accomplished through reduction in the use of CFCs in the manufacture of flexible foams and as aerosol propellants, the more efficient use of CFCs as solvents, and by reductions in many other applications. Cost estimates for the remaining reductions ‑ mainly in the fields of refrigeration, air conditioning, rigid foam, solvents, and fire protection ‑ vary widely and depend on the availability of near term drop‑in and other substitutes, costs of re‑engineering equipment and products, and the price, safety and energy efficiency of the substitutes.
The time‑path for phasing out some CFCs can substantially affect costs. A very rapid transition (much less than 10 years) would result in substantially higher costs due to capital abandonment. Individual governments and industries have significant opportunities to reduce costs, save money and improve energy efficiency if the best reduction strategy is chosen. Higher energy efficiency would reduce greenhouse gas emissions for an equivalent provision of service.
Technology Transfer
Developing countries have special needs and concerns as part of a global effort to protect stratospheric ozone. These concerns include: (1) the cost of CFC supply; (2) the cost of chemical substitutes; (3) the cost of imported products made now with CFCs and which, later, will be made with substitutes; (4) the cost of access to new technology; and (5) maintenance of trade with Parties to the Protocol in products made with or containing CFCs and halons.
‑ Even low‑use developing countries will want to adopt new technologies that cost about the same as or less than the old CFC technologies. For example, the potential cost savings from more energy efficient refrigerators may be more important in developing countries where income is low and energy costs are high. All countries can avoid new capital investment that would make them more dependent on CFCs and would result in later costs from abandonment of CFC capital when they begin their phase‑down.

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‑ Developing countries which are Party to the Protocol, need to be able to purchase CFCs for important needs such as food preservation until the alternatives are available. These countries may be able to purchase allowable quantities of CFCs at reasonable prices as production capacity becomes surplus in developed countries due to the CFC phase‑down. New investment in CFC production technology is now imprudent since there may not be time to depreciate the new capital and since ample supplies of CFCs may be available at low prices as developed countries phase‑down production. Some coordination may be necessary to assure a reliable reasonable price and supply. A low‑cost adequate supply to developing countries which are Party to the Protocol can avoid the cost of investment in old CFC technology.
‑ The new chemical substitutes (HFCs and HCFCs) are estimated to cost two to five times as much as CFCs when they become generally commercially available due to the increased cost of chemical ingredients, manufacturing costs, and capital cost. In some cases, the new chemicals may provide cost‑offsetting advantages such as improvements in energy efficiency or other product performance.
However, developing countries may need development assistance including capital grants and other technology transfer to afford these new chemicals. Countries that now produce CFCs, including developing countries may decide to become producers of some of the new chemicals. UVEP should carefully monitor this situation as new chemicals become available, mostly after 1993.

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