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

BMJ. 2011 Aug 4;343:d4521. doi: 10.1136/bmj.d4521.


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.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Accidents, Traffic / mortality*
  • Adolescent
  • Adult
  • Air Pollutants / adverse effects
  • Air Pollutants / analysis
  • Automobile Driving / statistics & numerical data*
  • Bicycling / physiology*
  • Bicycling / statistics & numerical data
  • Carbon Dioxide / analysis
  • Cause of Death
  • Environmental Exposure / adverse effects*
  • Environmental Exposure / analysis
  • Exercise / physiology*
  • Health Promotion
  • Humans
  • Middle Aged
  • Particulate Matter / adverse effects
  • Particulate Matter / analysis
  • Risk Assessment
  • Risk Factors
  • Spain / epidemiology
  • Survival Rate
  • Urban Health
  • Young Adult


  • Air Pollutants
  • Particulate Matter
  • Carbon Dioxide