ReviewHealth impact assessment of active transportation: A systematic review
Introduction
Contemporary car-ownership, and the vast network of roadway systems to accommodate it, adversely impact public health through environmental pathways such as air pollution, noise, greenhouse gas emissions, and traffic hazards (Haines and Dora, 2012). The convenience of motorized transportation has reduced dependence on physically-demanding travel while simultaneously increasing sedentary time spent (González-Gross and Meléndez, 2013). Today, globally, more than 30% of all adults are estimated to perform insufficient physical activity (PA) (Hallal et al., 2012). A lack of PA is associated with all-cause mortality, cardiovascular diseases (CVD), type 2 diabetes, cancer and impaired mental health (Physical Activity Guidelines Advisory Committee, 2008), and together with an energy-dense diet, the driving force of the progressing obesity epidemic (Ng et al., 2014).
The promotion of walking and cycling for transportation complemented by public transportation or any other ‘active’ mode, i.e. active transportation (AT), presents a promising strategy to not only address problems of urban traffic strain, environmental pollution and climate change, but also to provide substantial health benefits (de Hartog et al., 2010). Despite associated risks of exposure to traffic and to a lesser extent air pollution (de Nazelle et al., 2011), AT may overcome car dependence and increase PA levels (Lindsay et al., 2011).
In recent years, there has been growing interest in health impact assessment (HIA) as a method to estimate potential health consequences of non-healthcare interventions (Mindell et al., 2003). HIA aims at identifying the direction and magnitude of potential health impacts of these interventions in order to mitigate harms and increase health benefits (Mindell and Joffe, 2003). As until now longitudinal pre-/post-intervention studies in AT are scarce, HIA has to make do with scenarios to study what health effects would be if changes in transportation behavior took place. To our knowledge, despite evidence of AT health benefits (Cavill et al., 2008, Teschke et al., 2012, Xia et al., 2013), a systematic review quantifying health benefits and risks of AT does not yet exist. Therefore, we systematically reviewed studies conducting quantitative HIA of a mode shift to AT.
Section snippets
Methods
This review was performed following the PRISMA guidelines for reporting of systematic reviews (Moher et al., 2009). Systematic database searches of MEDLINE, Web of Science and Transportation Research International Documentation were conducted. Keyword combinations of “health impact assessment”, “active transportation”, “physical activity”, “traffic incidents”, “air pollution” and “noise” were used (Appendix A.1). Limits were English, Spanish, Dutch, French, or German language and abstract
Search results
The literature search produced a list of 3594 articles. Initial title screening identified 333 candidate studies. Abstract screening identified 130 candidate studies and independent full-text reading resulted in 30 eligible studies (Fig. 1).
Study characteristics
The 30 eligible studies were published between September 2001 and January 2015 (Table 1). Interventions that produced a mode shift, and of which health impacts were estimated, included measures which make AT more attractive (e.g. bike-sharing system), or
Discussion
Consistently, the vast majority of the reviewed HIAs estimated substantial net health benefits with a mode shift to active transportation (AT). Estimated benefits were largely due to increases in PA levels, which greatly outweighed associated detrimental effects of traffic incidents and air pollution exposure. Noise impacts were only considered secondary. The large range of benefit–risk and benefit–cost ratios observed may be attributable to distinctive HIA approaches, different assumptions on
Conclusions
We conclude that net health benefits of AT are substantial, irrespective of geographical context. Projected health gains by increases in PA levels exceed detrimental effects of traffic incidents and air pollution exposure. Thus, we encourage the promotion of AT, as associated health risks are minor.
Role of the funding source
This work was supported by the European project Physical Activity through Sustainable Transportation Approaches (PASTA), which has partners in London, Rome, Antwerp, Orebro, Vienna, Zurich, and Barcelona. PASTA (http://www.pastaproject.eu/home/) is a four-year project and funded by the European Union's Seventh Framework Program under EC‐GA No. 602624. The sponsors had no role in the study design; in the collection, analysis, and interpretation of data; in the writing of the report; and in the
Conflict of interest statement
All authors have completed the Preventive Medicine conflict of interest policy form and declare that there are no conflicts of interest.
Acknowledgments
We would like to thank our PASTA partners for helpful discussions and contributions to this review. Moreover, we thank Mireia Gascon for useful contributions on drafting this manuscript.
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