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The health risks and benefits of cycling in urban environments compared with car use: health impact assessment study

BMJ 2011; 343 doi: (Published 04 August 2011) Cite this as: BMJ 2011;343:d4521
  1. David Rojas-Rueda, predoctoral researcher123,
  2. Audrey de Nazelle, researcher123,
  3. Marko Tainio, researcher4,
  4. Mark J Nieuwenhuijsen, research professor123
  1. 1Center for Research in Environmental Epidemiology, C Doctor Aiguader, 88, 08003 Barcelona, Spain
  2. 2Municipal Institute of Medical Research (IMIM-Hospital del Mar) Barcelona
  3. 3CIBER Epidemiology and Public Health (CIBERESP) Madrid, Spain
  4. 4Systems Research Institute, Polish Academy of Sciences, Newelska 6, 01-447 Warsaw, Poland, and Department of Environmental Health, National Institute for Health and Welfare, Kuopio, Finland
  1. Correspondence to: D Rojas-Rueda drojas{at}
  • Accepted 13 June 2011


Objective To estimate the risks and benefits to health of travel by bicycle, using a bicycle sharing scheme, compared with travel by car in an urban environment.

Design Health impact assessment study.

Setting Public bicycle sharing initiative, Bicing, in Barcelona, Spain.

Participants 181 982 Bicing subscribers.

Main outcomes measures The primary outcome measure was all cause mortality for the three domains of physical activity, air pollution (exposure to particulate matter <2.5 µm), and road traffic incidents. The secondary outcome was change in levels of carbon dioxide emissions.

Results Compared with car users the estimated annual change in mortality of the Barcelona residents using Bicing (n=181 982) was 0.03 deaths from road traffic incidents and 0.13 deaths from air pollution. As a result of physical activity, 12.46 deaths were avoided (benefit:risk ratio 77). The annual number of deaths avoided was 12.28. As a result of journeys by Bicing, annual carbon dioxide emissions were reduced by an estimated 9 062 344 kg.

Conclusions Public bicycle sharing initiatives such as Bicing in Barcelona have greater benefits than risks to health and reduce carbon dioxide emissions.


  • Contributors: AdeN and MJN conceived and designed the study. DR-R and AdeN collected the data. All authors analysed and interpreted the data, wrote the manuscript, and edited and approved the final version for submission. AdeN and MJN are guarantors.

  • Funding: This work is part of the European wide project Transportation Air pollution and Physical ActivitieS: an integrated health risk assessment progamme of climate change and urban policies (TAPAS), which has partners in Barcelona, Basel, Copenhagen, Paris, Prague, and Warsaw. TAPAS is a four year project funded by the Coca-Cola Foundation, AGAUR, and CREAL.

  • Competing interests: All authors have completed the ICMJE uniform disclosure form at (available on request from the corresponding author) and declare: no support from any organisation for the submitted work; no financial relationships with any organisations that might have an interest in the submitted work in the previous three years; no other relationships or activities that could appear to have influenced the submitted work.

  • Ethical approval: Not required.

  • Data sharing: No additional data available.

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