Questions about Montreal Protocol

1. What are ozone? Where is ozone found?
Ozone (O3) is a triatomic molecule, consisting of three oxygen atoms. It is an allotrope of oxygen that is much less stable than the diatomic O2. Ground-level ozone is an air pollutant with harmful effects on the respiratory systems of animals. Ozone in the upper atmosphere filters potentially damaging ultraviolet light from reaching the Earth's surface. It is present in low concentrations throughout the Earth's atmosphere.
2. What are CFCs?
CFCs is chlorofluorocarbons.
3. How do CFCs destroy ozone?
The chlorofluorocarbons (CFCs) which are mainly responsible for ozone depletion. CFC molecules were stable enough to remain in the atmosphere until they got up into the middle of the stratosphere where they would finally (after an average of 50-100 years for two common CFCs) be broken down by uv radiation releasing a Cl atom. These Cl atoms might be expected to cause the breakdown of large amounts of O3 in the stratosphere.
4. What is the Montreal Protocol?
The Montreal Protocol on Substances That Deplete the Ozone Layer is an int'l treaty designed to protect the ozone layer by phasing out the production of substances believed to be responsible for ozone depletion.
- when was it signed?
The treaty was opened for signature on September 16, 1987 and entered into force on January 1, 1989 followed by a first meeting in Helsinki, May 1989. Since then, it has undergone seven revisions, in 1990 (London), 1991 (Nairobi), 1992 (Copenhagen), 1993 (Bangkok), 1995 (Vienna), 1997 (Montreal), and 1999 (Beijing).
- by whom was it signed?
At present, 191 nations have become party to the Montreal Protocol. Those 5 that are not as of September 2007 are Andorra, Iraq, San Marino, Timor-Leste and Vatican City.
- what was the goal of the Montreal Protocol? why was the Montreal Protocol important?
Series of stepped limits on CFC use and production, including
from 1991 to 1992 its levels of consumption and production of the controlled substances in Group I of Annex A do not exceed 150 percent of its calculated levels of production and consumption of those substances in 1986;
from 1994 its calculated level of consumption and production of the controlled substances in Group I of Annex A does not exceed, annually, 25 percent of its calculated level of consumption and production in 1986.
from 1996 its calculated level of consumption and production of the controlled substances in Group I of Annex A does not exceed zero.
There is a slower phase-out (to zero by 2010) of other substances (halon 1211, 1301, 2402; CFCs 13, 111, 112, etc) and some chemicals get individual attention (CCl4; 1,1,1-trichloroethane). The phasing-out of the less active HCFCs started only in 1996 and will go on till a complete phasing-out is achieved in 2030.
There are a few exceptions for "essential uses", where no acceptable substitutes have been found (eg., in the metered dose inhalers commonly used to treat asthma and other respiratory problems) or Halon fire suppression systems used in submarines and aircraft (but not in general industry).
5. How successful has the Montreal Protocol been?
Since the Montreal Protocol came into effect, the atmospheric concentrations of the most important CFCs and related compounds have either leveled off or decreased. Halon concentrations have continued to increase, as the halons presently stored in fire extinguishers are released, but their rate of increase has slowed and their abundances are expected to begin to decline by about 2020. While there have been reports of attempts by individuals to circumvent the ban, e.g. by smuggling, the overall level of compliance has been high. In consequence, the Montreal Protocol has often been called the most successful int'l environmental agreement to date.
6. What is being used as a replacement for CFCs?
CFCs were substituted with HCFCs, hydrochlorofluorocarbons.
I hope this can help with your understanding. =)