Now fears grow for ozone layer above Europe

Scientists will tomorrow fly a plane high into the world's protective ozone layer, amid increasing fears that it may be about to develop a hole over Britain and northern Europe.

The plane will take off near Munich in a EU mission to check reports that the stratosphere over the northern hemisphere faces rapid ozone destruction over the next few weeks.

If the hole developed, people living under it would be at increased risk of skin cancer and cataracts, the main cause of blindness.

The danger, which will also be assessed by scientists meeting in Zurich this week, has been provoked by the coldest winter on record, 19km above the Arctic, which provides the ideal conditions for the destruction of the ozone layer.

It is linked with global warming - as the atmosphere nearer the Earth warms, the stratosphere cools.

The ozone layer is a scattering of the blue-tinged gas through the 33km-deep stratosphere which is so thin that, if collected together, would form a girdle round the Earth no thicker than the sole of a shoe. It screens out harmful ultraviolet rays from the sun.

Without it no life would be possible on Earth. But, as it is weakened from being attacked by CFCs and other ozone-destroying pollutants, more radiation gets though to damage crops and kill the plankton that are the basis of marine life.

For more than 20 years a hole as big as the US and as high as Mt Everest has opened over Antarctica every southern spring. But since the continent is almost entirely uninhabited the hole has posed little danger to human health - though skin cancer rates in southern Chile are three times as high as elsewhere.

For just as long, scientists have feared that a similar hole would open up over the Arctic, with serious implications for human health since it would be over densely populated areas in Britain, northern Europe, North America and Russia.

So far it has not formed, largely because the Arctic does not get as cold as the Antarctic. But this year temperatures have been lower than at any time since records began. And there are more "polar stratospheric clouds", essential to ozone depletion, than at any time since pollution began threatening the ozone layer.

The EU says: "The concern is that the Arctic appears to be moving into Antarctic-like conditions, which will result in an increase in ultraviolet radiation levels that will have consequences on human health."

Dr Neil Harris, of the European Ozone Research Co-ordinating Unit in Cambridge, says ozone levels in the Arctic are 40 per cent lower than normal for this time of year.

But scientists are divided on the likelihood of a hole developing. The crunch will come in the next few weeks when sunlight - which plays a key role in destruction - returns after the dark Arctic winter.

If the hole does form, the risk to people will depend on weather conditions and other local factors, Dr Harris says. For example, clouds will shield people from radiation, while sunny days will expose them to it.

But, even at its worst, the depletion is likely to be only half as severe as over Antarctica.

The ozone layer

* Ozone is a scattering of the blue-tinged gas through the 33km-deep stratosphere which screens out harmful ultraviolet radiation from the sun.

* It is so thin that if collected together it would form a girdle round the Earth no thicker than the sole of a shoe.

* Without it life on Earth would be impossible.

- INDEPENDENT