In 1974 the American scientists Mario Molina and Sherwood Rowland showed that ChloroFluroCarbons (CFC's) played an active role in the depletion of the ozone layer.

CFC's are stable industry gases containing mainly chlorine, fluorine and bromine.

They are used in refrigeration systems, air conditioners, aerosols, solvents and in the production of some types of packaging.

In 1985, British scientists discovered the hole in the ozone layer at the Halley Bay station in Antarctica.

At first, they were convinced that there was something wrong with their instruments.

The instruments were replaced, but the results stayed as alarming as before.

When their conclusions were published in the scientific magazine Nature, the world recognized that something had to be done and quickly.