Ozone to Blame for `Early Autumn'
Geoffrey Lean Environment Correspondent, The Independent (London, England)
THE leaves of hundreds of thousands of British trees are turning brown early this year, after a summer of damaging air pollution.
Unpublished Government figures, obtained last week for the Independent on Sunday, show that levels of ozone have exceeded official danger limits for trees for weeks, and often months, over most of rural Britain since May.
In areas as far apart as Sussex and Scotland, Devon and North Yorkshire, the pollution, mainly from car exhausts, stayed above the internationally agreed limits for almost every day throughout the height of the summer.
The figures, compiled from official computerised records by Friends of the Earth, show that up to last Monday the gas exceeded the limits laid down by the World Health Organisation on 89 days in Cumbria, 93 days in North Yorkshire, 101 in Devon and the South-West and 103 in Sussex. (The highest figure, 123 days, was recorded in the Scottish Highlands, but this is distorted because the monitoring station is high on a mountain, where ozone levels are elevated.)
Ozone - one of the factors in the asthma epidemic which currently affects one in every seven British children - is now being implicated in an alarming sickness sweeping through the country's woods and hedgerows. By one official measurement, more than half of Britain's trees are seriously or moderately affected - nearly three times as many as seven years ago.
For the second year running, trees throughout Britain have begun changing colour from mid-August. This "early autumn" is a classic sign of the sickness; another, bare or sparsely foliated treetops, has been even more widespread in the past few summers.
Last year the Forestry Commission acknowledged that "early autumn" was taking place, but blamed drought - in what proved to be an exceptionally wet summer. This year it denies it is happening: "There is some yellowing of leaves, but no early autumn."
At the Department of the Environment a senior official did admit: "As a member of the public I feel that autumn has started early. But there has not been a systematic survey that would tell us that this is true."
A DOE review group, which six years ago dismissed suggestions that pollution might be damaging trees, has also admitted, in its latest report, that "the available evidence suggests that ozone is likely to adversely affect tree health in parts of Britain". …