Walking is good for you... even in the smog
Walking or cycling is good for you even in polluted cities, researchers have found.
The health benefit of physical activity outweighs the harm caused by chemicals and dust puffed out by traffic and industry, according to Cambridge academics.
Air pollution is a major problem in British cities, and is estimated to contribute to 40,000 early deaths in Britain every year.
People who exercise in polluted areas are thought to put themselves at increased risk, because they take deeper breaths, inhaling more of the toxic pollution and particles that do such damage.
But a new study, published in the journal Preventive Medicine, suggests that the act of exercising outweighs this risk, because physical activity reduces the risk of diseases such as diabetes, heart disease, and several cancers.
Experts at the Centre for Diet and Activity Research - a collaboration between the universities of Cambridge and East Anglia - used computer simulations to compare the risks and benefits of exercising in polluted areas around the world.
Only 1 per cent of cities are so polluted that the risks start to overcome the benefits of physical activity after half an hour of cycling.
Study leader Dr Marko Tainio, of the University of Cambridge, said: ‘Our model indicates that in London health benefits of active travel always outweigh the risk from pollution.
‘Even in Delhi, one of the most polluted cities in the world – with pollution levels ten times those in London – people would need to cycle over five hours per week before the pollution risks outweigh the health benefits.
‘We should remember, though, that a small minority of workers in the most polluted cities, such as bike messengers, may be exposed to levels of air pollution high enough to cancel out the health benefits of physical activity.’
Senior author Dr James Woodcock added: ‘Whilst this research demonstrates the benefits of physical activity in spite of air quality, it is not an argument for inaction in combating pollution.
‘It provides further support for investment in infrastructure to get people out of their cars and onto their feet or their bikes – which can itself reduce pollution levels at the same time as supporting physical activity.’