The discovery of the ozone hole The British Antarctic Survey has been monitoring for many years, the total column ozone levels at its base at Halley Bay in the antarctica Monitoring data indicate that column ozone levels have been decreasing since 1977 This observation was later confirmed by satellite data (TOMS-Total Ozone Mapping spectrometer) Initially satellite data were assumed to be wrong with values lower than 190DUThe discovery of the ozone hole • The British Antarctic Survey has been monitoring, for many years, the total column ozone levels at its base at Halley Bay in the Antarctica. • Monitoring data indicate that column ozone levels have been decreasing since 1977. • This observation was later confirmed by satellite data (TOMS-Total Ozone Mapping Spectrometer) – Initially satellite data were assumed to be wrong with values lower than 190DU