The ozone layer and the ozone hole

In short: The ozone layer in the stratosphere filters most of the Sun’s harmful UV radiation. The “ozone hole” is a strong thinning of this layer, mainly over Antarctica.

In more detail: Ozone (O₃) forms and breaks down in an equilibrium. Chlorine and bromine compounds from CFCs disturb it and destroy ozone.

In detail

• Cause: Chlorofluorocarbons (CFCs) from coolants and spray cans rose into the stratosphere.
• Montreal Protocol (1987): An international agreement banned CFCs. The ozone layer is recovering slowly.
• UV protection: More UV-B radiation raises the risk of skin cancer and eye damage.
• Ground-level ozone: It is an irritant gas and part of summer smog, so something quite different from the protective layer.
• Success: It is regarded as an example of effective international environmental protection (treibhauseffekt).