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Air pollution on city streets cancels positive health effects of exercise in over 60s (2017-12-20)

WExposure to air pollution on city streets is enough to counter the beneficial health effects of exercise in older adults, according to new research.

Led by scientists from the MRC-PHE Centre for Environment and Healthopens in new window at Imperial College London and King's College London, the study, published in The Lancet, recruited 119 volunteers over the age of 60 through the Royal Brompton Hospital, who were either healthy, had stable chronic obstructive pulmonary disease (COPD), or stable heart disease.

The volunteers walked for two hours in two London settings at midday: in a relatively quiet part of leafy Hyde Park and along a busy section of Oxford Street, which has regularly breached air quality limits set by the World Health Organization.

Physical measurements were taken before and after the walks to show the effects of the exercise on cardiovascular health, including measurements of lung volume exhaled, blood pressure, and the degree to which their blood vessels could expand.

Analysis revealed that all participants benefitted from a stroll in the park, with lung capacity improving within the first hour and a significant lasting increase for more than 24 hours in many cases.

By comparison, a walk along Oxford Street led to only a small increase in lung capacity in participants, far lower than recorded in the park.

Blood flow also increased after exercise, with decreases in blood pressure and an increase in heart rate.

Arteries became less stiff in those walking in Hyde Park with a maximum change from baseline of more than 24% in healthy and COPD volunteers, and more than 19% in heart disease patients.

This effect was drastically reduced when walking along Oxford Street, however, with a maximum change in arterial stiffness of just 4.6% for healthy volunteers, 16% for those with COPD and 8.6% for heart disease.

Professor Fan Chung, senior author from the MRC-PHE Centre for Environment and Health, and the National Heart & Lung Institute at Imperial College London, 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 study 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.

For people living in the inner city, it may be difficult to find areas where they can go and walk away from pollution, there may be a cost associated as they have to travel further away from where they live or work.

These are issues that mean we really need to reduce pollution by controlling traffic.
That should allow everyone to be able to enjoy the health benefits of physical activity in any urban environment.”

The authors add that it is possible that stress could account for some of the physiological differences seen between the two settings, with the increased noise and activity of Oxford Street having an effect.
They also emphasise that while the study only involved two relatively short walks, the findings suggest that repeated exposures to air pollution would not be beneficial to our respiratory and cardiovascular systems.

For more information
The Lancet
Respiratory and cardiovascular responses to walking down a traffic-polluted road compared with walking in a traffic-free area in participants aged 60 years and older with chronic lung or heart disease and age-matched healthy controls: a randomised, crossover study

The Medical Research Council (MRC)

Imperial College London

King's College London