Montreal Protocol Ozone Layer

Confirmation of the destmetion of ozone by chlorine and bromine from halofluorocarbons has led to international efforts to reduce emissions of ozone-destroying CPCs and Halons into the atmosphere. The 1987 Montreal Protocol on Substances That Deplete the Ozone Layer (150) (and its 1990 and 1992 revisions) calls for an end to the production of Halons in 1994 and CPCs, carbon tetrachloride, and methylchloroform byjanuary 1, 1996. In 1993, worldwide production of CPCs was reduced to 50% of 1986 levels of 1.13 x 10 and decreases in growth rates of CPC-11 and CPC-12 have been observed (151). 

Ozone Layer was signed, which set a timetable for phasing out the production and use of CFCs, including halons. The date for phaseout of the manufacture of halons according to the latest Copenhagen Meeting was January 1, 1994 (UNEP, Montreal Protocol on Substances that Deplete the Ozone Layer—Final Act 1987, 1987). 

The new law buUds on the market-based structure and requirements currently contained in EPA s regulations to phase out the production of substances that deplete the ozone layer. The law requires a complete phase-out of CFCs and halons with interim reductions and some related changes to the existing Montreal Protocol, revised in June 1990. 

Montreal Protocol on Substances that Deplete the Ozone Layer. The phase-out of CFCs began on Jnly 1, 1989, and by 1997, a hydroflnorcarbon, HFC134a, with zero ozone depletion potential, became the dominant refrigerant in the United States. The phase-out of CFCs in developing countries is on a slower schedule. 

United Nations Environmental Program. (1995). Montreal Protocol on Substances that Deplete the Ozone Layer— Report on the. RcBigcration, Air Conditioning and Heat Pumps Technical Options Committee. New York Author. 

Several of the commercially available 16,000 chlorinated and brominated compounds have already been regulated or harmed, CFCs, DDT and chlorinated biphenyls are typical examples. Many others are being phased out according to the Montreal Protocol on Substances that Deplete the Ozone Layer. This includes chlorinated solvents, methyl bromide and halons (e.g. CF3Br). The milder ozone destroyers, hydrochlorofluorocarbons (HCFCs) will also, eventually, be phased out. 

Until recently, chlorofluorocarbons (CFCs) for refrigeration were major end products of HF chemistry, but these compounds are being phased out in accord with the Montreal Protocols because of their effect on the ozone layer (see Chapter 15). 

Montreal Protocol The UN convention on the trade of materials damaging the ozone layer... 

Montreal Protocol on Substances That Deplete the Ozone Layer, 26 1LM 1541, 1987. 

Batchelor, T. 1998. Montreal protocol on substances that deplete the ozone layer. United Nations Environmental Program. Assessment of alternatives to methyl bromide. Methyl bromide technical... 

In order to prevent the destruction of the Earth s ozone layer, the international community has agreed upon restrictions during a convention (The Vienna Convention, 1985) and a protocol was written (The Montreal Protocol, 1987). The Montreal Protocol requires the progressive phase-out of the produc-... 

Methane is removed continually from the atmosphere by reaction with OH radicals (Section 8.3). In contrast, chlorofluorocarbons and related volatile compounds are inert under the conditions of the lower atmosphere (troposphere), so atmospheric concentrations of these refrigerants and solvents will tend to increase as long as releases continue. The chief concern over chlorofluorocarbons is that they are a major factor in destruction of the stratospheric ozone layer (Section 8.3). They have been banned under the Montreal Protocol of 1988, but it is important that whatever substitutes (inevitably greenhouse active) are introduced to replace them degrade relatively quickly in the troposphere to minimize any contribution they may be capable of making to greenhouse warming. 

There has been an unprecedented level of international cooperation toward banning ozone-destroying chemicals. The first major step was the signing of the 1987 Montreal Protocol on Substances That Deplete the Ozone Layer, which called for the reduction of CFC production to one-half of 1986 levels by the year 1998. However, only a few years after the protocol was ratified, in 1990, scientists confirmed that the CFC problem was much more serious than they believed in 1987 when the protocol was drafted. The protocol was soon amended to call for cessation of all CFC production by 1996. Even with the protocol in place and the continued cooperation of all signatory nations, however, the ozone-destroying actions of CFCs will be with us for some time. Atmospheric CFC levels are not expected to drop back to the levels found before the ozone hole was formed until sometime in the 22nd century. 

CFCs) and halons over the next decade, as mandated by the Montreal Protocol for the Protection of the Ozone Layer, will affect the chlorine burden of the stratosphere. Hydrochlorofluorocarbons (HCFCs) can be used as substitutes for the CFCs for a few decades without having a substantial impact on the chlorine burden of the stratosphere because they are primarily destroyed in the troposphere by reactions with OH before they are able to deliver the chlorine to the stratosphere. The elimination of CFCs and the temporary use of HCFCs into the early part of the next century must be carefully orchestrated to minimize the peak chlorine loading and promote the most rapid reduction of the chlorine burden of the stratosphere (56, 87). Another issue is the effects that perturbations to the reactive nitrogen abundances will have on the abundances of reactive chlorine. A better understanding and clarification of the direct heterogeneous conversions of chlorine species on both PSCs and sulfate aerosols are also needed. 

The Montreal Protocol on Substances that deplete the ozone layer [3] came into force on... 

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