Timeline of the Ozone layer

Ozone loss was first detected in the stratosphere over the Antarctic

Aug 22, 1970

Dramatic 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) who were monitoring the atmosphere above Antarctica from a research station much like the picture to the right.

Note the sudden change in the curve after about 1975.

Oct 22, 1975

first ozone hole

Oct 22, 1985

The British Antarctic Survey's first documentation of the Antarctic ozone hole in 1985

decreased ozone levels

Aug 22, 1990

In the northern polar regions, ozone levels in the early 1990s measured ten percent lower than those estimated in the late 1970s

the ozone layer was cut in half

Oct 22, 1994

By 1994, the total ozone in October was less than half its value during the 1970s, 20 years previous.

largest hole in ozone history

Sep 24, 2006

The largest ozone hole: 24 September 2006