Air pollution in parts of central London is so bad it cancels out the benefits of doing exercise outdoors, according to new research by a charity.
The British Heart Foundation says the cardiovascular benefits of a brisk walk along Oxford Street are completely negated by exposure to air pollution for the over 60s.
The research, published in the Lancet and carried out by Imperial College London and Duke University in North Carolina, compared the benefits of exercising in Oxford Street and Hyde Park in people aged 60 and over.
The researchers found levels of pollution - including fine particulate matter, black carbon and nitrogen dioxide - were significantly higher on Oxford Street compared to Hyde Park.
Volunteers who took a walk in Hyde Park experienced a decrease in the stiffness of their arteries, a benefit normally seen after exercise. In contrast, volunteers who walked on Oxford Street had a “worrying increase” in artery stiffness following exercise.
The results suggest that poor air quality can cancel out exercise benefits and demonstrate the health impacts of even short-term exposure to air pollution.
The research also showed that medications for heart disease, such as statins, might protect against some of the damage caused by air pollution.
Simon Gillespie, chief executive at the British Heart Foundation, 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.”
Previous BHF research has shown that long-term exposure to air pollution leads to inflammation in the blood vessels, including those supplying the heart, and promotes the build-up of fatty plaques in the linings of blood vessels, which can eventually lead to a heart attack or stroke.
“Combined with evidence from other recent studies, our findings underscore that we can’t really tolerate the levels of air pollution that we currently find on our busy streets,” said Fan Chung, professor of respiratory medicine and head of experimental studies medicine at Imperial College’s National Heart and Lung Institute.
London Mayor Sadiq Khan has pledged to make reducing air pollution one of his top priorities and announced a global network to tackle the issue while on a trip to Delhi this week.
With support from the network of cities, he will set up a trial million-pound street-by-street air monitoring system to analyse pollution in over 1,000 hotspots including in schools, hospitals, construction sites and busy roads.
The government, which wants to completely phase out petrol and diesel cars by 2040, is under pressure to do more to bring down harmful levels of toxic fumes faster.
“Our hope is that this study will add to the evidence city leaders need to contribute to policies that will encourage preservation of green spaces,” said Jim Zhang, professor of global and environmental health at the US’s Duke University.
“As economic growth and urbanisation happen around the world, lots of cities are left with very little green space.
“People like outdoor exercise. We should provide them with spaces to enable that instead of giving them no choice but to walk and cycle through busy, polluted streets.”