City air pollution can cancel out the beneficial effects of exercise in older adults, say scientists.
A London study found that short-term exposure to traffic fumes greatly reduced the positive impact of walking on the heart and lungs.
Previous research has shown that breathing in polluted air, especially fine particles from diesel engines, increases the risk of heart disease and death.
For the new study 119 volunteers over the age of 60 were asked to walk for two hours in a relatively quiet part of Hyde Park and along a busy section of Oxford Street.
All the participants, recruited through London’s Royal Brompton Hospital, were either healthy or had a stable lung condition or non-progressing heart disease.
The study showed that all the volunteers benefitted from a stroll in the park, with lung capacity improving within the first hour, arteries becoming significantly less stiff and blood flow increasing and lowering in pressure. In contrast, walking along busy Oxford Street had little impact on arterial stiffness and led to only a small increase in lung capacity.
These are issues that mean we really need to reduce pollution by controlling traffic
Fan Chung, a professor from Imperial College London, who led the research reported in The Lancet journal, said: “These findings are important as for many people, such as the elderly or those with chronic disease, very often the only exercise they can do is to walk.
“Our research suggests that we might advise older adults to walk in green spaces, away from built-up areas and pollution from traffic.
“It is possible that studies such as this could support new air quality limits, it shows that we can’t really tolerate the levels of air pollution that we currently find on our busy streets.
“These are issues that mean we really need to reduce pollution by controlling traffic.”
The study was funded by the British Heart Foundation, whose chief executive Simon Gillespie said: “Air pollution contributes to around 40,000 premature deaths in the UK every year, and the extent of its damage to our cardiovascular health is becoming clearer all of the time.
“Exercise is crucial in reducing the risk of a heart attack or stroke, but it seems dangerous levels of air pollution could be erasing these benefits in older adults.
“When exercising it’s best to avoid highly-polluted areas, swapping them for green spaces or even back streets where pollution is lower. This will ensure you can experience the full benefits of exercise.
“However, telling joggers to avoid polluted streets is not a solution to the problem. The government must put forward bold measures to make all areas safer for our hearts and clean up the UK’s toxic air.”
The research was carried out in collaboration with US colleagues from Duke University.