Boris bikes: health benefits outweigh risks from injury and pollution

The London cycle hire scheme has had a positive overall effect on the health of its users by increasing physical activity within the capital, according to the results of a large-scale modelling study published today in the BMJ. These benefits outweighing the potential negative impacts from injuries and exposure to air pollution, say the authors.

The scheme has been used far more by younger than older adults and by men than women. The research found that men and the relatively few older cyclists (45 and older) who use the scheme achieve the most pronounced benefits, while women and younger riders do not benefit as much.

The study authors suggest that reducing the injury risks cyclists face, as well as encouraging greater use of the scheme among older people, would further amplify the health benefits.

Physical inactivity has been linked previously with a wide range of health problems including heart disease, stroke, diabetes, dementia, depression and many forms of cancer. Research suggests that most people in London would benefit from increasing their activity levels and cycling offers a good opportunity to integrate this activity into everyday life. Public bike sharing schemes, like London's 'Boris bikes', have been implemented in over 600 cities in 49 countries. However, to date there is only limited evidence on the health effect of these schemes.

Senior author Dr Anna Goodman of the London School of Hygiene and Tropical Medicine, in collaboration with experts from the Medical Research Council and UCL, assessed the London cycle hire scheme using a computer model that weighed up changes from physical activity, injuries and exposure to air pollution over one year (April 2011- March 2012). They used data from every journey made on a hire bike during this period, combined with information from surveys of cycle hire users and data on travel, physical activity, road traffic collisions and air pollution in London.

The team compared the effects of the cycle hire scheme against the likely mode of transport (tube, bus, walking, etc) if the cycle hire scheme did not exist. They looked at two scenarios for injury rates - from reported accidents and injuries among cycle hire users, as well as background rates of injuries and deaths among all cyclists in London (including those with their own bikes). They determined health benefits using a measurement called Disability Adjusted Life Years (DALYs) - the number of years of life lost to illness, disability or premature death.

The benefits of the cycle hire scheme substantially outweighed the harms when weighed against observed injury rates for hired bikes. When injury rates for all cycling in central London were used as a comparison, the benefits were smaller and disappeared entirely for women (largely due to higher death rates among female cyclists following collisions with HGVs in London). This difference reflects a trend towards lower injury rates on the cycle hire bikes than for cyclists in general in the area covered by the scheme.

Dr Goodman, NIHR Postdoctoral Fellow, said: "When the cycle hire scheme was introduced, there were widespread concerns that increasing the number of inexperienced cyclists in central London would lead to higher injury rates. Our findings are reassuring, as we found no evidence of this. On the contrary, our findings suggest that the scheme has benefited the health of Londoners and that cycle hire users are certainly not at higher risk than other cyclists."

However the authors caution that the health benefits were not as pronounced in younger adults, particularly the under-30s. One reason for this is that many of the diseases affected by physical activity, such as heart disease, are less common in younger people. Even though older adults might be more at risk of injury than younger adults, the benefits from being active increase much more quickly. They add that reducing road traffic danger is another key factor - if cycling in central London was as safe as in cities in the Netherlands, the health benefits from initiatives like the cycle hire scheme would be far more substantial. The Netherlands manages to achieve high levels of cycling with low risks, not by focusing on helmets and hi-vis, but by providing high quality infrastructure that physically protects cyclists from busy, fast moving traffic.

The research was funded by the Medical Research Council and National Institute for Health Research, and through the UK Clinical Research Collaboration.


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