Cancer, stroke and heart disease, diabetes, obesity and changes related to dementia have been linked to air pollution – but a new study says that the benefits of walking and cycling outside outweigh these effects.
A University of Cambridge study, published in Preventative Medicine, has found that the benefits of regular exercise can often be so high that they even outweigh the negative impact of air pollution.
Air pollution has a major impact on health, with the Royal College of Physicians estimating that health problems from exposure to air pollution could cost as much as £20 billion a year. Nearly 10,000 deaths a year in London are blamed on air pollution, and EU pollution levels are frequently breached.
Many people engage in what the researchers call "active travel" such as cycling or walking, which can provide health benefits. But this kind of activity can also expose people to air pollution.
Researchers used a computer simulation to collate the levels of active travel and air pollution in locations across the world; they say it is the "first to model the risks and benefits of walking and cycling across a range of air pollution concentrations around the world".
Results from the simulation suggest that "air pollution will not negate the health benefits of active travel" in the majority of urban areas.
"Our model indicates that in London health benefits of active travel always outweigh the risk from pollution," said lead author Marko Tainio. "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."