Health benefits of green spaces in the living environment: A systematic review of epidemiological studies

Objectives: The objective was to systematically review the literature examining the relationship between quantity and quality of green spaces in the living environment and three health outcomes: perceived general health, perceived mental health, and (all-cause) mortality. Methods: An online search was followed by a selection process applying eligibility criteria. Three levels of evidence were defined based on the number and quality of the studies, and the consistency of the findings. Fourteen studies on perceived general health, 19 on mental health and seven on all-cause mortality were included in the review. Results: The evidence synthesis showed strong evidence for significant positive associations between the quantity of green space (objectively measured around the residence) and perceived mental health and all-cause mortality, and moderate evidence for an association with perceived general health. There were insufficient studies on the quality of green spaces to conduct an evidence synthesis. A few studies provided indications that associations depend on subgroups such as gender, age groups and groups with different social economic status, but the findings were mixed. Conclusions: Further research should focus on exploring relationships between more detailed characteristics of green space and more specific health outcomes in different population subgroups and in different countries. To strengthen the evidence-base, studies with more sophisticated designs, e.g. natural experiments, are needed. (C) 2015 Elsevier GmbH. All rights reserved.