Benefits of cycling and walking 'outweigh air pollution risk' in cities

Study finds only 1% of cities in world have such high levels of pollution that the activities could prove detrimental to health

The health benefits of cycling and walking outweigh the harm from inhaling air loaded with traffic fumes in all but the world's most polluted cities, according to a study.

An international team of researchers who have modelled the effects say only 1% of cities in the world have such high levels of air pollution that cycling or walking could make a person's health worse.