Recent research, reported as part of the BBC's So I Can Breathe series, has found that exposure to fine particulate matter on Bath’s London Road is greater for a taxi driver than for a cyclist. The full report is currently available on the iPlayer.
For ten days, a cyclist and a taxi driver were asked to carry air quality monitors while travelling around the city.
While high nitrogen dioxide levels were experienced by the cyclist, levels of small particulate matter from diesel fumes – associated with respiratory and cardiovascular conditions – were consistently higher for the taxi driver.
During one journey, the pollution in the taxi was as high as in Beijing.
For six of the ten days, the taxi driver involved in the experiment was exposed to pollution in excess of World Health Organisation’s (WHO) recommended limits. In contrast, the cyclist’s exposure always remained below.
Professor Gavin Shaddick of the University of Bath explained: “Being in a car is not like being in a sealed box.
“Winding up your windows may give you the perception that the air isn’t coming through the windows and that you might have reduced your exposure to air pollution, but the intakes for the car’s air system are at the front of the car. And the problem is, they’re generally at the level of the exhaust pipe of the car in front of you.”
He added: "The advantages of cycling, of course, are that you are getting health benefits from actually having exercise and it’s been shown that that would outweigh the harm that would be caused by breathing in bad air.”
Last year scientists at the University of Cambridge and the University of East Anglia modelled the risks and benefits of walking and cycling in varying levels of air pollution around the world. They found that only in the worst one per cent of polluted cities would the ill effects of poor air quality outweigh the benefits of exercise.
The exception was bike messengers where the health benefits of cycling could be cancelled out by the long periods spent in areas of poor air quality.
Also last year, a team of 50 cycle couriers from London same-day courier service Gophr were equipped with carbon monoxide monitors to map the capital's pollution. The project, run by former Labour minister Paul Drayson's firm Drayson Technologies, aims to create "the world's most advanced air pollution map".