How much pollution are London's cycle commuters exposed to when travelling into central London each day? Ben Barratt spoke to ITN news this month about what effect route choice has on 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% 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 center of the city. They and also tend to be higher during morning rush hour, which coincides with most cycle Journeys into London.

Ben and Martin 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 Martin's office near King's Cross. Martin took a more direct but more polluted route through Brixton, while Ben 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 Ben 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, Martin was exposed to around three times as much particulate pollution as Ben. Significant parts of Martin'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 spoke to our college Dr Rossa Brugha on the health impacts of pollution at his lab at Queen Mary Hospital. Rossa 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 your exposure to pollution by taking quieter cycling routes is the best option.

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Item date 06/02/2014