The study followed eight cycle couriers working in London for six weeks, regularly testing how effectively their lungs were delivering oxygen to the body.

The levels of particulate pollution (PM) were, at the time, below the World Health Organisation’s recommended safe maximum of 50mg per cubic metre but, nevertheless, were shown to significantly impair lung function.

The calculated ‘pollution load’ delivered to the couriers’ lungs varied over the six-week testing period, but the study found that when the load was low, lung function improved by almost 5%.

When the load was high, lung performance dropped by a similar per cent, suggesting acute inflamation of the lungs.

“Previously, these sort of changes in lung function have only been observed in people with asthma, or at much higher levels of particulate air pollution”, said Prof Alison McConnell from the Centre for Sports Medicine & Human Performance at Brunel University.

“Unfortunately the lungs are a very good conduit, a very good route for getting all sorts of materials into the body, It takes less than 10 seconds for the ‘hit’ from a cigarette to reach the brain, which provides a very good illustration of how rapidly material can pass from the lungs and into the body.”

Professor McConnell added that cyclists are especially vulnerable to the effects of particulate matter, not only are they closer to the source of the pollution, but their higher breathing rate increases the amount of pollution they inhale.

“The problem for the urban cyclist is that exercise magnifies the amount of pollution that they inhale,” she said.

“The deposition of some particles can be as much as 16 times higher during exercise. This means a 30-minute cycle ride can equate to eight hours of sitting by the roadside.”

David Gibbs

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