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Cycle commuting and pollution exposure study with ITV

How much pollution are London's cycle commuters exposed to when travelling into central London each day? 

Dr Ben Barratt, Lecturer in Air Quality Science at King’s College London, spoke to ITV news this month about what effect route choice has on a cyclist’s exposure in London, measuring black carbon and particulates on two routes using personal sampling monitors. 

Cycling has increased in popularity over the last 10 years, with the number of trips rising by 173 per cent since 2001. The highest growth in cycling trips has been seen in central London with the majority either starting and ending or passing through the centre. Pollution levels in London are highest in the centre of the city. They also tend to be higher during morning rush hour, which coincides with most cycle Journeys into London. 

Dr Barratt and Martin Stew – the ITV presenter – set off from Martin's house in south London, taking two contrasting routes chosen by King's & City of London's new City Air App, to Mr Stew's office near King's Cross. Mr Stew took a more direct but more polluted route through Brixton, while Dr Barratt took back roads through the Clapham area. 

Both wore personal PM2.5 particulate and black carbon monitors. These monitors give a good indication of exposure to traffic emissions and specifically diesel pollutants. 

Although though Dr Barratt cycled further, there was less traffic on his route and as a result they both arrived at King's Cross at the same time. Analysis of the monitors showed that despite it being an overcast January morning, Mr Stew was exposed to around three times as much particulate pollution as Dr Barratt. 

Significant parts of Mr Stew's journey were also above the World Health Organisation limit annual of 25 ug/m3 for PM2.5. Pollution levels in London have led many cyclists to question whether increased exposure to pollution by cycling outweighs the health benefits of the exercise. 

ITV also spoke to Dr Rossa Brugha, Queen Mary University, on the impact of pollution on health at his lab at Queen Mary Hospital.  Dr Brugha explained how fine particles affect lung growth and increase the risks of heart attacks and strokes over the long-term but, citing studies performed Barcelona, suggested that the cardiovascular health benefits of cycling still outweigh the effect of increased pollution exposure. Decreasing exposure to pollution by taking quieter cycling routes is the best option.