Where are we exposed to the most air pollution?

Where is air pollution exposure at its highest?

BBC South's environment correspondent, Jon Cuthill, has been doing the mileage to find out.

He has teamed up with experts at the University of Portsmouth to test the air pollution on his commute to and from work.

John cycled nine miles (14km) every day for a week, using various equipment to monitor air pollution and the results were surprising.