In the early 1980s, thanks to a combination of ground-based measurements and satellite observations, scientists detected a significant reduction in the ozone layer, Earth’s natural shading, especially in Antarctica. The information made it possible to understand the magnitude of the “hole in the ozone layer”, as well as to identify the use of chemical substances such as chlorofluorocarbons (CFCs), present in aerosols, refrigerators or air conditioners, as its main cause.

The ozone layer acts as a protective shield for the Earth, as stratospheric ozone absorbs part of the sun’s ultraviolet radiation, which is harmful to living beings. Instead, excess ozone on the Earth’s surface that is formed from pollutants can be harmful to humans, plants, and animals.

In response, in 1985 governments from around the world met under the Vienna Convention for the Protection of the Ozone Layer. This treaty established a framework for international cooperation to investigate, monitor and prevent damage to the ozone layer.

With the support of 197 countries, the Montreal Protocol was adopted in 1987, with measures to begin phasing out chlorofluorocarbons and other substances, thus setting in motion the recovery of the ozone layer. At present, it is estimated that more than 99 per cent of ozone-depleting chemicals have been eliminated. In addition, it is expected that by the middle of this century it will recover its thickness, reaching levels prior to those of 1980.

To commemorate this recovery, the International Day for the Conservation of the Ozone Layer is celebrated every September 16. Although the battle is not yet completely won, this anniversary highlights an example of success that demonstrates that joint action and political will can go a long way in mitigating an environmental crisis.