The ozone layer is a massive shield that surrounds the Earth, 50kms above the surface of the planet. Ozone is a special molecule of oxygen: O3. It is up to 20kilometres thick and most of this gas is found in the stratosphere.
Ozone gases are our protection against UVB radiation. This damaging radiation is emitted by the Sun and is extremely dangerous. The ozone layer absorbs around 99% of this harmful radiation, and is not used up in the process, so why are there giant holes in this shield?
The ozone hole is largely over the Antarctic and is between 21 and 24 million square kilmoetres in size. The hold is caused by ozone reacting with CFCs – pollutants used in refrigeration.
Fast Fact: The largest recorded ozone hole occurred in 2006 at 20.6 million square miles (33.15 million square kilometres).