Air pollution cancels out benefits of exercise

Henrietta Brewer
December 7, 2017

A new United Kingdom study examined how even short-term exposure to tiny particles of soot or dust in traffic fumes can affect the arteries and lungs - and the research is likely applicable to Australia, says one expert.

"However, this should not be seen as a barrier to many older people for whom walking is the only exercise they do. We suggest that, where possible, older adults walk in parks or other green spaces away from busy roads". "In the United Kingdom physical inactivity is the fourth largest cause of disease and mortality and contributes to around 37,000 premature deaths in England every year". Air pollution is responsible for around 5.5 million premature deaths worldwide each year.

On the other hand, people who walked for two hours in a large city park - away from direct exposure to street-side traffic fumes - reduced arterial stiffness by more than 24% in healthy and COPD volunteers and more than 19% in heart disease patients. All participants had abstained from smoking for the past 12 months, and continued any medications as usual throughout the study.

Participants were asked to walk for two hours in two London settings at midday; either in a quiet part of green and leafy Hyde Park or along a busy section of Oxford Street - which has regularly breached the air quality limits set by the World Health Organisation.

Three to eight weeks later, the participants swapped routes.

In healthy participants the walk in Hyde Park led to a 7.5 per cent improvement in the amount of air they could expel in one breath and improvements in blood flow which persisted up to 26 hours after exercise. By contrast, lung capacity improved only slightly during the Oxford Street walk - and did not last. They were either healthy, had stable chronic obstructive pulmonary disease (COPD), or stable ischemic heart disease.

Jonathan Grigg, professor of paediatric respiratory and environmental medicine at Queen Mary University of London, said: "Children in London and other large urban areas are now inhaling traffic-derived pollutants that increase the risk of pneumonia and asthma, and stunt lung growth".

The researchers also note that stress from the increased noise and activity of Oxford Street may have had an effect on the study's results.

Walking is often recommended for older people, but the study from Imperial College London and Duke University in the US suggests that the over-60s and those with lung and heart problems should steer clear of urban areas with heavy traffic.

"Exercise is crucial in reducing the risk of a heart attack or stroke, but it seems risky levels of air pollution could be erasing these benefits in older adults".

"Our study provides a clear message to improve the quality of the air we all share", the authors conclude.

"Since the vast majority of the most toxic vehicles on our roads are diesel cars and vans, the UK Government must introduce a national "remove and replace" diesel vehicle policy to protect the health of children - both born and to be born".

Dr Gayan Bowatte, from the Melbourne School of Population and Global Health at The University of Melbourne, says the findings are relevant to Australia.

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 highest recoded mean annual NO2 in our studies was 23 ppb, which was a relatively low level compared to South East Asian countries". The findings were published in the Lancet medical journal.

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