The hole in the ozone layer ‘is not healing up as people had thought’

The hole in the ozone layer which protects against ultraviolet radiation is not actually recovering over built-up areas, scientists have warned.

The ‘ozone hole’ became the focus of an iconic campaign against pollution, but scientists had believed it had recovered, after the Montreal Protocol’s ban on substances such as CFCs.

But a new study has shown that while it is recovering in Antarctica, where it was worst depleted, the ozone layer is thinning in the lower stratosphere over non-polar areas.

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The reason is not known, but it could be to do with chemicals used in paint stripper which were previously believed to be too volatile to affect the stratosphere.

The new study found that while ozone levels are recovering in the upper stratosphere, they are actually dropping in the lower stratosphere.

William Ball of ETH Zurich university in Switzerland told The Guardian: ‘The finding of declining low-latitude ozone is surprising, since our current best atmospheric circulation models do not predict this effect.

‘Very short-lived substances could be the missing factor in these models.’

Prof Joanna Haigh at Imperial College London said, ‘The study is in lower to mid latitudes, where the sunshine is more intense, so that is not a good signal for skin cancer.

‘It is a worry. Although the Montreal protocol has done what we wanted it to do in the upper stratosphere, there are other things going on that we don’t understand.’