Elsevier

Environmental Research

Volume 158, October 2017, Pages 301-317
Environmental Research

Exploring pathways linking greenspace to health: Theoretical and methodological guidance

https://doi.org/10.1016/j.envres.2017.06.028Get rights and content

Highlights

  • Although it appears that greenspace benefits health, the pathways are unclear.

  • We have organized pathways into three domains that emphasize greenspace functions.

  • Pathways likely intertwine and vary by context, populations and health outcomes.

  • We identify diverse challenges in measurement and analysis that require attention.

  • Research guided by our discussion will better efforts to enable greenspace-related health benefits.

Abstract

Background

In a rapidly urbanizing world, many people have little contact with natural environments, which may affect health and well-being. Existing reviews generally conclude that residential greenspace is beneficial to health. However, the processes generating these benefits and how they can be best promoted remain unclear.

Objectives

During an Expert Workshop held in September 2016, the evidence linking greenspace and health was reviewed from a transdisciplinary standpoint, with a particular focus on potential underlying biopsychosocial pathways and how these can be explored and organized to support policy-relevant population health research.

Discussions

Potential pathways linking greenspace to health are here presented in three domains, which emphasize three general functions of greenspace: reducing harm (e.g. reducing exposure to air pollution, noise and heat), restoring capacities (e.g. attention restoration and physiological stress recovery) and building capacities (e.g. encouraging physical activity and facilitating social cohesion). Interrelations between among the three domains are also noted. Among several recommendations, future studies should: use greenspace and behavioural measures that are relevant to hypothesized pathways; include assessment of presence, access and use of greenspace; use longitudinal, interventional and (quasi)experimental study designs to assess causation; and include low and middle income countries given their absence in the existing literature. Cultural, climatic, geographic and other contextual factors also need further consideration.

Conclusions

While the existing evidence affirms beneficial impacts of greenspace on health, much remains to be learned about the specific pathways and functional form of such relationships, and how these may vary by context, population groups and health outcomes. This Report provides guidance for further epidemiological research with the goal of creating new evidence upon which to develop policy recommendations.

Introduction

Overall, 54% of the world's population now lives in urban settings, a term which can encompass relatively small towns of less than 500,000 inhabitants to megacities of more than 10 million inhabitants (United Nations, 2014). This percentage is projected to reach 66% by 2050 (United Nations, 2014). Urbanization is an important current and future challenge and it entails change in how people interact with the environment (Zenghelis and Stern, 2016, Nieuwenhuijsen et al., 2017). This includes quantitatively and qualitatively diminished contact with natural environments. Consequently, the extent to which population exposure to natural environments may be causally related to beneficial health outcomes has become the focus of an emerging field in environmental epidemiology during the past few decades.

The existing reviews and meta-analyses that have considered this question conclude that various measures of exposure to residential greenness (i.e. vegetation level) or green spaces such as parks, gardens and forests (hereon referred to generically only as “greenspace” when both greenness and green spaces are meant; Taylor and Hochuli, 2017) are beneficial for multiple measures of health for urban populations in relatively high-income countries (e.g. Hartig et al., 2014; James et al., 2015; van den Berg et al., 2015; Gascon et al., 2015, Gascon et al., 2016b; Dzhambov et al., 2014; de Keijzer et al., 2016). In particular, beneficial associations with greenspace have been observed for outcomes such as general health (e.g. Dadvand et al., 2016; Sugiyama et al., 2008), mental health (e.g. de Vries et al., 2013; McEachan et al., 2016), obesity (e.g. Ellaway et al., 2005; Lovasi et al., 2013b), birth weight (e.g. Hystad et al., 2014; Markevych et al., 2014a), childhood behavioural development (e.g. Balseviciene et al., 2014; Amoly et al., 2014) and mortality (e.g. Mitchell and Popham, 2008; Villeneuve et al., 2012; Donovan et al., 2013). However, not all studies find evidence of a beneficial association between greenspace and the health outcomes considered (e.g., Flouri et al., 2014; Mowafi et al., 2012; Potestio et al., 2009; Markevych et al., 2016b) and some even report associations opposite to those expected (Cummins and Fagg, 2012, Pereira et al., 2012, Prince et al., 2011, Richardson et al., 2012). An interesting example comes from the allergy field, where increasing greenness was positively associated with childhood allergies in one German study area but inversely associated with the same outcomes in a second German study area, despite the use of identical epidemiological methods (Fuertes et al., 2014). This lack of a consistent relationship was replicated in seven birth cohorts from five countries two years later (Fuertes et al., 2016). Similarly, Casey et al. (2016) reported no association between greenness and term birth weight among ~ 13000 newborns in Pennsylvania, despite the fact that this association is among the most consistent and widely replicated (Dzhambov et al., 2014). More “conflicting” results are likely and therefore, more specific and process-oriented research should be encouraged to improve our understanding of the complexities underlying associations between greenspace and health outcomes.

In September 2016, a workshop entitled “Exploring Potential Pathways Linking Greenness and Green Spaces to Health” took place in Munich-Herrsching, Germany. The attendees included experts from various complementary disciplines, covering environmental and social epidemiology, exposure science, environmental psychology, forestry, geography, remote sensing and city planning. This Report summarizes the discussions that took place, beginning with the primary aim of the Workshop, which was to consider the evidence linking greenspace and health from a transdisciplinary standpoint, while focusing on potential underlying pathways (Section 2, Fig. 1). In addition, recommendations for future research, in terms of study designs, exposure assessment and analytical approaches (Section 3, Table 1, Table 2), as well as policy implications (Section 4), were identified. In line with the aims of the Workshop, the objective of this Report is to provide guidance for further research based on the experiences of interdisciplinary researchers interested in greenspace-health relationships. It is not intended to be an exhaustive review of the literature.

Section snippets

Potentially beneficial influences of greenspace on health

A variety of biopsychosocial pathways have been proposed to explain the health benefits of greenspace (e.g., Hartig et al., 2014; Kuo, 2015). These can be parsimoniously organized into three domains that emphasize different general functions of greenspace (Fig. 1).

This organizational approach is novel but not without foundations. Each of the domains maps onto a widely applied perspective on ways to modify the environment in order to support adaptation and promote health (Hartig, 2008, Hartig et

Study designs

Cross-sectional designs are commonly used and help to identify potential greenspace-health associations. However, their methodological limitations are well recognized, in particular, their inability to establish causality and their vulnerability to residential self-selection (e.g. healthier people will tend to choose to live in greener places (Toftager et al., 2011)). Instead, longitudinal, intervention and (quasi)experimental research designs should be employed whenever possible. Longitudinal

Policy implications

Actors outside of academia may question the need for research on greenspace and health, as it can be viewed as “common sense”. One could argue that we should simply green our cities and the health improvements will follow. But city planners, politicians and other practitioners involved in urban greening often rightfully require hard evidence demonstrating the public health benefits of different quantity, quality and accessibility scenarios. Indeed, without acknowledging the many likely nuances,

Conclusion

In this Report, we provide a framework in which the many potential pathways by which greenspace can benefit health are organized into three domains that emphasize three general functions of greenspace: reducing harm, restoring capacities and building capacities.

This Report also provides guidance for further epidemiological research, upon which policy recommendations can be developed. As the percentage of people living in urban environments continues to rise, there is an urgent need to better

Funding

The Expert Workshop was funded by the European Cooperation in Science and Technology (COST; BM1201 - Developmental Origins of Chronic Lung Disease), the European Union's Horizon 2020 Research and Innovation programme (ALEC Study, #633212) and the Institute for Occupational, Social, and Environmental Medicine, Ludwig-Maximilians-University of Munich. Elaine Fuertes is supported by a Marie Skłodowska-Curie Individual Fellowship (H2020-MSCA-IF-2015; 704268). ISGlobal is a member of CERCA Programme

Conflicts of interests

The authors declare that they have no conflicts of interest.

Acknowledgement

We would like to thank two anonymous Reviewers for their insightful comments which helped us to improve the manuscript greatly.

References (277)

  • M. van den Berg et al.

    Visiting green space is associated with mental health and vitality: a cross-sectional study in four European cities

    Health Place

    (2016)
  • P. Cariñanos et al.

    Urban green zones and related pollen allergy: a review. Some guidelines for designing spaces with low allergy impact

    Landsc. Urban Plan.

    (2011)
  • J.S. Christensen et al.

    Pregnancy and childhood exposure to residential traffic noise and overweight at 7 years of age

    Environ. Int.

    (2016)
  • P. Dadvand et al.

    Green space, health inequality and pregnancy

    Environ. Int.

    (2012)
  • P. Dadvand et al.

    Inequality, green spaces, and pregnant women: roles of ethnicity and individual and neighbourhood socioeconomic status

    Environ. Int.

    (2014)
  • P. Dadvand et al.

    The association between greenness and traffic-related air pollution at schools

    Sci. Total Environ.

    (2015)
  • P. Dadvand et al.

    Green spaces and general health: roles of mental health status, social support, and physical activity

    Environ. Int.

    (2016)
  • A.M. Dalton et al.

    Neighbourhood green space is associated with a slower decline in physical activity in older adults: a prospective cohort study

    SSM - Popul. Health

    (2016)
  • A.Y. Davis et al.

    Combined vegetation volume and "greenness" affect urban air temperature

    Appl. Geogr.

    (2016)
  • G.H. Donovan et al.

    Trees in the city: valuing street trees in Portland, Oregon

    Landsc. Urban Plan.

    (2010)
  • G.H. Donovan et al.

    The relationship between trees and human health: evidence from the spread of the emerald ash borer

    Am. J. Prev. Med

    (2013)
  • A. Dzhambov et al.

    Association between residential greenness and birth weight: systematic review and meta-analysis

    Urban For. Urban Green.

    (2014)
  • A.M. Dzhambov et al.

    Green spaces and environmental noise perception

    Urban For. Urban Green.

    (2015)
  • A.M. Dzhambov et al.

    Children's blood pressure and its association with road traffic noise exposure – a systematic review with meta-analysis

    Environ. Res

    (2017)
  • J. Elliott et al.

    Neighbourhood cohesion and mental wellbeing among older adults: a mixed methods approach

    Soc. Sci. Med.

    (2014)
  • D. Faries et al.

    Evaluating the impact of unmeasured confounding with internal validation data: an example cost evaluation in type 2 diabetes

    Value Health

    (2013)
  • E. Flouri et al.

    The role of urban neighbourhood green space in children's emotional and behavioural resilience

    J. Environ. Psychol.

    (2014)
  • U. Fransson et al.

    Leisure home ownership and early death: a longitudinal study in Sweden

    Health Place

    (2010)
  • N. Garg et al.

    A critical review of principal traffic noise models: strategies and implications

    Environ. Impact Assess. Rev.

    (2014)
  • M. Gascon et al.

    Normalized difference vegetation index (NDVI) as a marker of surrounding greenness in epidemiological studies: the case of Barcelona city

    Urban For. Urban Green.

    (2016)
  • M. Gascon et al.

    Residential green spaces and mortality: a systematic review

    Environ. Int

    (2016)
  • A. Gidlöf-Gunnarsson et al.

    Noise and well-being in urban residential environments: the potential role of perceived availability to nearby green areas

    Landsc. Urban Plan.

    (2007)
  • B. Giles-Corti et al.

    Increasing walking: how important is distance to, attractiveness, and size of public open space?

    Am. J. Prev. Med.

    (2005)
  • B. Giles-Corti et al.

    The influence of urban design on neighbourhood walking following residential relocation: longitudinal results from the RESIDE study

    Soc. Sci. Med.

    (2013)
  • R. Grazuleviciene et al.

    Surrounding greenness, proximity to city parks and pregnancy outcomes in Kaunas cohort study

    Int J. Hyg. Environ. Health

    (2015)
  • D.S. Grigsby-Toussaint et al.

    Sleep insufficiency and the natural environment: results from the US Behavioral Risk Factor Surveillance System survey

    Prev. Med.

    (2015)
  • C.J. Gronlund et al.

    Vulnerability to extreme heat by socio-demographic characteristics and area green space among the elderly in Michigan, 1990–2007

    Environ. Res.

    (2015)
  • M. Grundström et al.

    Limited effect of urban tree vegetation on NO2 and O3 concentrations near a traffic route

    Environ. Pollut.

    (2014)
  • K. Agay-Shay et al.

    Green spaces and adverse pregnancy outcomes

    Occup. Environ. Med.

    (2014)
  • E. Amoly et al.

    Green and blue spaces and behavioral development in Barcelona schoolchildren: the BREATHE project

    Environ. Health Perspect.

    (2014)
  • M. Annerstedt et al.

    Green qualities in the neighbourhood and mental health–results from a longitudinal cohort study in Southern Sweden

    BMC Public Health

    (2012)
  • T. Astell-Burt et al.

    Does access to neighbourhood green space promote a healthy duration of sleep? Novel findings from a cross-sectional study of 259 319 Australians

    BMJ Open

    (2013)
  • T. Astell-Burt et al.

    Greener neighborhoods, slimmer people? Evidence from 246,920 Australians

    Int J. Obes.

    (2014)
  • T. Astell-Burt et al.

    Is neighborhood green space associated with a lower risk of type 2 diabetes? Evidence from 267,072 Australians

    Diabetes Care

    (2014)
  • T. Astell-Burt et al.

    Neighbourhood green space and the odds of having skin cancer: multilevel evidence of survey data from 267 072 Australians

    J. Epidemiol. Community Health

    (2014)
  • T. Astell-Burt et al.

    Neighbourhood green space is associated with more frequent walking and moderate to vigorous physical activity (MVPA) in middle-to-older aged adults. Findings from 203,883 Australians in The 45 and Up Study

    Br. J. Sports Med.

    (2014)
  • T. Astell-Burt et al.

    The association between green space and mental health varies across the lifecourse. A longitudinal study

    J. Epidemiol. Community Health

    (2014)
  • T. Astell-Burt et al.

    Do low-income neighbourhoods have the least green space? A cross-sectional study of Australia's most populous cities

    BMC Public Health

    (2014)
  • T. Astell-Burt et al.

    Large-scale investment in green space as an intervention for physical activity, mental and cardiometabolic health: study protocol for a quasi-experimental evaluation of a natural experiment

    BMJ Open

    (2016)
  • D.E. Aylor et al.

    Perception of noise transmitted through barriers

    J. Acoust. Soc. Am.

    (1976)
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