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Ozone layer first discovered
The ozone layer was first discovered, measure, and identified -
G.M.B Dobson began measuring the atomosphere
British scientist began measuring the amout of ozone in the atmosphere -
Thomas Midgley Jr. synthesized the first chlorofluorocarbons
Thomas midgley synthesized the first chlorofluorocarbons -
Scientist began to suspect CFC's
Scientist first began to suspect CFC's in the atmosphere -
220 dobsons are found
The value of 220 Dobson Units is chosen since total ozone values of less than 220 Dobson Units were not found in the historic observations over Antarctica. -
The British Antarctic Survey's first documentation of the Antarctic ozone hole
The British Antarctic Survey's first documentation of the Antarctic ozone hole and subsequent NSF-funded study of the phenomenon alerted the world to the danger of chlorofluorocarbons, or CFCs. -
a decrease in the amout of ozone in the stratosphere
Folklore has it that when the first measurements were taken in 1985, the drop in ozone levels in the stratosphere was so dramatic that at first the scientists thought their instruments were faulty, but concluded that the ozone layer was thnning -
The first global agreement to restrict CFCs
The first global agreement to restrict CFCs came with the signing of the Montreal Protocol in ultimately aiming to reduce them by half by the year 2000. -
A major European campaignas organised to study the polar regions during the winter
A major European campaign, the European Arctic Stratospheric Ozone Experiment (EASOE) was organised to study the polar regions during the winter of 1991/92. -
An argeement revison
Two revisions of this agreement have been made in the light of advances in scientific understanding, the latest being in -
European scientists conducted SESAME
In 1994 and 1995 European scientists conducted SESAME, the Second European Stratospheric Arctic and Mid-latitude Experiment. They investigated the processes occurring at both high and mid-latitudes and how they are linked. At the same time a US-led expedition considered similar processes in the southern hemisphere. -
the total ozone is less than half of the october in the 1970's
By 1994, the total ozone in October was less than half its value during the 1970s, 20 years previous. This dramatic fall in ozone was caused by the use of man-made chemicals known as 'halocarbons' which include the well-known CFCs commonly used in fridges and so on. These CFCs had made their way into the upper atmosphere where the much stronger UV radiation from the Sun had broken them down into their component molecules, releasing the potentially damaging chlorine (and bromine) atoms, which, -
industry halts production
Recognising their responsibility to the global environment they have agreed to halt production of the main CFCs. -
The latest European campaign is called THESEO (
The latest European campaign is called THESEO (THird European Stratospheric Experiment on Ozone) which takes places from 1997-1999. Scientists from many European countries, including some of this site, are collaborating on a wide range of experiments to determine the processes responsible for depleting ozone in the lower stratosphere but at mid-latitudes over the northern hemisphere. -
Susan Solomon leds the ozone experiment
That research team led by National Medal of Science winner, Susan Solomon, conducted observations that have significantly advanced our understanding of the global ozone layer and changed the direction of ozone research. -
argreement goes to the industry
Agreement has been reached on the control of industrial production of many halocarbons until the year