So says Canadian engineer Alexander Bigazzi from the University of British Columbia. He used a series of equtions to calculate the speed that walkers, joggers or cyclists need to travel to minimise the pollution they breathe in. He applied these to a theoretical population of 10,000 people, both male and female, of varying ages.
He found that this speed happens to be the level at which most cyclists would normally travel, about 3-8km an hour walking, 8-13km an hour jogging, and 12-20km an hour cycling on flat ground. Going above these speeds, according to his model, increases the potential harm caused by air pollution, which contributes towards 40,000 deaths a year in the UK.
However, other studies have argued that the health benefits of cycling outweigh any pollution-related risks, unless you live in an area with extreme pollution.