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Air pollution: how big a problem is it for cyclists?

Air Pollution in London

Air pollution in London. Photograph: Peter Macdiarmid/Getty Images


Powered by Guardian.co.ukThis article titled “Air pollution: how big a problem is it for cyclists?” was written by Peter Walker, for theguardian.com on Thursday 20th February 2014 06.00 UTC

It’s a scenario familiar to any urban cyclist: you’re stuck behind a fume-belching bus or taxi, a choking diesel aroma wafting through your lungs. You think: is this really the healthy option?

The good, if simple, answer from pollution experts is: yes. Cycling does remain many, many times better for your health than not cycling, even factoring in exposure to pollution and the risk of accident. What’s more surprising is that on two wheels you might even be exposed to less of the smelly stuff than those using other forms of transport.

The more full answer is, inevitably, slightly mixed. Air pollution is a very real danger, with even conservative estimates gauging it prematurely kills almost 30,000 Britons a year, making it the most deadly public health hazard apart from smoking.

And yet, experts say, there are a range of measures cyclists can take to limit their exposure, from taking quieter back routes, to cycling at particular times of the day. There’s even an argument that pollution masks, once common in cities like London but little seen these days, might help. But more of that later.

Gary Fuller, an expert on air quality at King’s College London, notes that the villain behind most of the peril in urban areas is the diesel engine. While petrol vehicles have somewhat cleaned up their emissions in recent years, diesels still emit lots of particulate nasties like black carbon, and are increasingly common in new cars. He says:

People should be worrying about diesel traffic and particle exposure, and also about nitrogen dioxide. The thing about these is they haven’t really improved in urban areas for the last decade or so. We’ve managed to clean up air pollution emissions in terms of nitrogen dioxide from petrol cars.

Buy a petrol car today and it will emit about four-tenths as much in oxides as a car you bought 10 or 12 years ago. But for diesels, despite the fact we have ever-tighter emissions standards the conditions in which the emissions test is performed doesn’t really reflect the real world.

It is, Fuller adds, a national issue:

It’s not just a London problem. You can go out into apparently rural areas with an A-road travelling through a small village and you can find EU limits being exceeded.

That said, the way people are exposed to airborne pollution is not as straightforward as you might think. Fuller’s KCL colleague, Ben Barratt, carried out a test in which a group of Londoners – an ambulance driver, a cycle courier, a toddler, a pensioner, an office worker and a school pupil – spent the same 24-hour period fitted with GPS trackers and an instrument to measure their exposure to black carbon.

Barrett stresses this was no more than an illustrative demonstration study, but the graph of cumulative exposure is nonetheless interesting, with the cycle courier encountering the second-least amount of less black carbon overall, and being exposed to less than the ambulance driver during work hours as a proportion of the total day.

Cumulative Black Carbon Exposure

A graph produced by Ben Barratt of King’s College London shows the cumulative exposure to black carbon. Photograph: King’s College London


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