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1970s scientists began to be concerned about damage to this protective layer caused by atmospheric pollution.
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In 1974 two United States chemists predicted that a class of chemicals called chlorofluorocarbons, widely used in aerosol spray cans, would seriously damage the ozone layer.
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May 1985 British scientists produced the first direct evidence that this was actually happening.
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In September 1987 an international meeting in Montreal created the world's first environmental convention.
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In September 1987 an international team returned from the Antarctic to reveal that the cause of the ozone hole was human-produced chlorine and bromine molecules escaping to the stratosphere
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In June 1990 an international meeting in London voted for a strengthened Montreal Protocol under which CFCs, halons and other ozone-destroying chlorine compounds would be phased out by 2005
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In spring 2006 the ozone hole over Antarctica was arguably the largest on record, with average ozone levels over Antarctica the thinnest ever observed.
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In about 2018 a decrease in the size of the ozone hole is expected and decreasing levels of ozone-destroying CFCs have already been observed. Temperature trends in the stratosphere are responsible for the delayed effect.