1. Stratosphere – The ozone layer is located in the lower stratosphere, a calm atmospheric region between
the troposphere and the mesosphere which is not affected by weather or winds.
2. CFCs last for ages – While the use of CFC-causing products has reduced since 1970, CFCs have a long lifetime and so ozone depletion will continue for several decades yet.
3. Dissociation – Ozone causes that funny smell after a storm. The electrical breakdown of oxygen helps ozone to form. Because ozone is denser it sinks to ground level where we can smell it.
4. Record hole – NASA is keeping close tabs on the ozone over Antarctica. The largest hole recorded to date was in 2000 at 29.9 million square kilometres (11.5 million square miles).
5. When ozone goes bad – Ozone is good as long as it stays in the stratosphere where it protects us from the Sun. But if human pollutants increase ozone near the ground it can become harmful.