There is fresh evidence that the ozone layer is thinning over the UK and northern Europe. Scientists are alarmed by the depletion, which was previously thought to be a problem mostly confined to the southern hemisphere. Ozone protects the Earth from the sun's ultra-violet radiation, and doctors are concerned that if it is eroded more people will sufer from skin cancer. Meteorological readings taken in the stratosphere over the Arctic show that in six of the past 10 winters ozone has thinned to half its normal concentration.