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measurements and observations of the changes in ozone that occur over Antarctica
measurements and observations of the changes in ozone that occur over Antarctica -
Dramatic loss of ozone in the lower stratosphere over Antarctica was first noticed in the 1970s
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By 1994, the total ozone in October was less than half its value during the 1970s
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two United States chemists predicted that a class of chemicals called chlorofluorocarbons would seriously damage the ozone layer
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British scientists produced the first direct evidence that this was actually happening
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British scientists produced the first direct evidence that this was actually happening
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Folklore has it that when the first measurements were taken in 1985
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an international meeting in Montreal created the world's first environmental convention
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the cause of the ozone hole was human-produced chlorine and bromine molecules escaping to the stratosphere and, under ultraviolet radiation, breaking down into 'free' atoms which can break ozone molecules apart
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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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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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a decrease in the size of the ozone hole is expected and decreasing levels of ozone-destroying CFCs have already been observed