Methyl Montreal Protocol

In addition, EPA must ensure that Class I chemicals be phased out on a schedule similar to that specified in the Montreal Protocol—CFCs, halons, and carbon tetrachloride by 2000 methyl chloroform by 2002—but with more stringent interim reductions. Class II chemicals (HCFCs) will be phased out by 2030. Regulations for Class I chemicals will be required within 10 months, and Class II chemical regulations will be required by December 31, 1999. 

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. 

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... 

The Montreal Protocol stated that the production and consumption of all substances that deplete the ozone layer would be phased out by the year 2000 in developed countries. (Methyl chloroform would be phased out by 2005.) The chemicals that are named in the agreement include CFCs, halons, carbon tetrachloride, methyl chloroform, and methyl bromide. Once CFC production and consumption are stopped, scientists hope that the ozone layer will recover within 50 or 60 years. The success of the Montreal Protocol depends however, on the co-operation of both developed and developing countries. 

Montreal Protocol This counters the depletion of the ozone layer of the atmosphere and is mainly related to ozone depleting substances, such as methyl bromide, a widely used pesticide. 

Many of the commonly used solvents for precision cleaning are being eliminated due to their suspected involvement in reduction of the earth s ozone layer. Production of these chemicals, known as ozone depleting substances (ODS), is being eliminated by an international treaty known as the Montreal Protocol. This is an international agreement, first proposed in 1987 and entered into force in 1989, which limits production of chlorofluorocarbons (CFCs) and halons due to concerns that these substances were damaging the earth s ozone layer. The Montreal Protocol was modified in 1990 and again in 1992 to completely eliminate the production of chlorofluorocarbons, carbon tetrachloride, methyl chloroform (1,1,1 -trichloroethane) and halons by 1996. 

Montreal Protocol on Substances that Deplete the Ozone Layer. An international agreement signed by almost all industrialized nations which sets a phase out for the production of ozone depleting substances (ODS s). The compounds to be phased out include chlorofluorocarbons (CFC s), halons, carbon tetrachloride, methyl chloroform (1,1,1-trichloroethane), and hydrochlorofluorocarbons (HCFC s). The original phaseout dates were revised in the 1992 modification of the Montreal Protocol, morbidity. Rate of incidence of disease. 

Halons, which, like CFCS, are nonflammable, were primarily used as propellants in fire extinguishers. The fact that they contain bromine, however, makes these substances, like methyl bromide, highly destructive of the ozone layer. An amendment to the Montreal Protocol banned their use by 1994. 

Worldwide limits for solvents in the atmosphere were discussed and set (and subsequently updated) at a conference in Montreal in 1988. The protocol issued after the conference, the Montreal Protocol, laid down a timetable for solvent use reduction for chlorofluorocarbon solvents and specifically for carbon tetrachloride and methyl chloroform. The use of the former to be eliminated by 1997, and the latter to be reduced by 70% by the year 2000, and then to be totally banned by 2005. 

Studies indicate that the Montreal Protocol has been effective to date. The 2002 Scientific Assessment of Ozone Depletion shows that the rate of ozone depletion is slowing. Stratospheric concentrations of methyl chloroform are falling, indicating that emissions have been reduced. Concentrations of other ozone-depleting substances, such as CFCs, are also decreasing. It takes years for these substances to reach the stratosphere and release chlorine and bromine atoms. For this reason, stratospheric chlorine levels are still near their peak, but they are expected to decline slowly in years to come. If all parties to... 

FIGURE 4.53 Global average mixing ratios in parts per trillion (ppt(v)) of several CFCs, HCFCs, HFCs, PFCs, and SFg. The effect of the Montreal Protocol phaseout of CFC-11, CFC-12, and methyl chloroform (CH3CCI3) on atmospheric mixing ratios can clearly be seen, as can the subsequent increase in atmospheric mixing ratios of HCFCs and HFCs used as substitutes for CFCs. Adapted from IPCC (2007). 

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