Letter: Ozone hole will be slow to heal

Sir: In his article on the ozone hole (14 November) your environment correspondent failed to mention the most worrying aspect of the matter. The important "ozone eaters" remain in the atmosphere for over 100 years. So an immediate total ban will have little effect on the increasing ozone holes until the middle of the next century.

In spite of the Montreal Protocol CFCs are still being produced, particularly in the Third World. This seems destined to continue since neither politicians nor commercial interests are prepared to think long-term. It is also worth remembering that the ozone layer is thicker over the tropics so the problem is essentially one for the middle and high latitudes.

Dr BRIAN D GILES

Selly Oak, Birmingham