Pollutionwatch: Olympic athletes vulnerable to bad air quality

Final of the Men's 1500 Metres
Olympic athletes are vulnerable to pollution, here Sebastian Coe of Great Britain leads team mates Steve Cram and Steve Ovett in the final of the 1500 metres at the 1980 Olympic Games. Photograph: Tony Duffy/Getty Images

The effects of air pollution on athletes came to the fore during the 1984 Los Angeles Olympics, where Steve Ovett collapsed with respiratory problems after the 800 metres final, citing air pollution as a major trigger for his exercise induced asthma. In 2008, images of smog shrouding Beijing's bird's nest stadium were shown around the world and this summer the spotlight will be on London.

Westerly winds normally export the UK's air pollution to the continent but when this is reversed we can receive polluted air that has passed over many European countries. Strong summer sun can then drive atmospheric chemical reactions to produce ground-level ozone and particle pollution characteristic of summertime smog. This happened during May's warm weather causing moderate ground level ozone over the whole UK. The first high ozone of the year was measured near Dartmoor on 26 May and at Sevenoaks, Kent on the 28th.

Last year's cycle trial event showed how road closures can effectively reduce local traffic pollution but endurance athletes are especially vulnerable to ground-level ozone because of their accumulated pollution dose during long events. Ground level ozone forms over several days from combined pollution from many countries and London can do little to manage this on its own. However ozone concentrations peak in the mid to late afternoon meaning that careful scheduling of endurance events can significantly reduce athletes' exposure.