Air pollution kills 12,500 a year

About 12,500 people a year die in Britain from pollution caused by traffic and industry and the toll is likely toincrease, says a leading environmental scientist.

The amount of low-level ozone has almost doubled in the last century and now stands at about 50 parts per billion, Professor Roy Harrison told the British Association Annual Science Festival at Leicester University.

In the past decade, scientists have suggested there is evidence of a link between atmospheric ozone and asthma. Pollution warnings from the Department of Environment advise asthmatics to use extra medication or stay indoors when ozone levels are high - they are at their worst during hot summer days.

Measures to lessen pollution, such as the Clean Air Act, had dramatically reduced some substances in the air such as sulphur dioxide, said Professor Harrison. But nitrogen oxides and other secondary pollutants, such as nitrates, had not been effectively controlled. While peak concentrations of ozone had fallen across western Europe in general over the past decade, the average concentration had increased and was expected to go on increasing, added Professor Harrison.

By the end of the century, concentrations could have risen to 80 parts per billion. Although Britain is reducing emissions that cause ozone pollution, other countries, such as India and China, are not.

Levels of ozone are, therefore, rising across the northern hemisphere "at quite a worrying rate", said Professor Harrison.

Most deaths were caused to the infirm, particularly those with respiratory illnesses. Children who do regular outdoor exercise, and therefore breathe in more ozone pollution, are also vulnerable.