Pollution 'no excuse' for avoiding physical activity in the world's major cities

Results of a new study suggest that, in almost every instance, city pollution is no excuse for avoiding physical activity. The study, conducted by researchers at London’s Imperial College, found that, while air pollution is worsening in many cities, the benefits of what it called ‘active travel’ always outweigh pollution’s effects in all but the world’s most polluted cities.

Smog at dawn over New York City.

Smog at dawn over New York City. Image by Charles Smith / CC BY 2.0

Published in the journal Preventive Medecine last week, the study emphasised the health benefits of active travel, namely walking and cycling. Researchers in Brazil, Spain, and Switzerland, and the Universities of Cambridge and Edinburgh, and Imperial College London, in the UK, assessed the risks and benefits of active travel in relation to pollution using computer simulations. They concluded that the benefits of half an hour of cycling outweighed the risks in all but one per cent of the cities on the World Health Organisation’s Ambient Air Pollution Database.

While it didn’t take into account individual factors or the risks of periods of temporarily heightened pollution, the study found, in a city like London, the benefits of exercise always outweigh the risks. This remains the case even in cities that experience extreme levels of pollution. In Delhi, for example, where pollution levels are ten times higher than London’s, “people would need to cycle over five hours per week before the pollution risks outweigh the health benefits,” said the study’s leader, Dr Marko Tainio from the MRC Epidemiology Unit at the University of Cambridge.

Another researcher, Dr Audrey de Nazelle of the centre for environmental policy at London’s Imperial College, said, “Now we know that in 99% of world cities it is always beneficial to your health to cycle as long as you want.” She hopes the research will “encourage walking and cycling and help people lead healthier lives.”

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