loss of ozone in the lower stratosphere over Antarctica was first noticed in the 1970s by a research group from the British Antarctic Survey (BAS)
two United States chemists predicted that a class of chemicals called chlorofluorocarbons (CFCs)
Period: to
test
Drop ozone layers
The ozone layer levels dropped dramaticaly
an international meeting in Montreal created the world's first environmental convention.
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
the ozone hole over Antarctica was arguably the largest on record, with average ozone levels over Antarctica the thinnest ever observed. Polar stratospheric clouds (PSCs), which form during periods of