1970s scientists began to be concerned about damage to this protective layer caused by atmospheric pollution.
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.
May 1985 British scientists produced the first direct evidence that this was actually happening.
In September 1987 an international meeting in Montreal created the world's first environmental convention.
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
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
In spring 2006 the ozone hole over Antarctica was arguably the largest on record, with average ozone levels over Antarctica the thinnest ever observed.
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.