The image shows the ozone hole in purple during October 1986.

British scientists began their measurements of Antarctic ozone in 1957. The amount of ozone overhead should follow a regular seasonal pattern. But in 1977 deviations were observed, and by 1984 it was clear that the Antarctic stratosphere was changing progressively.

This phenomenon is the result of emissions mainly of chlorofluorocarbons (CFCs) and halons used in refrigeration, industrial solvents and fire control.