The health benefits of urban green spaces: a review of the evidence.

BACKGROUND: Urban development projects can be costly and have health impacts. An evidence-based approach to urban planning is therefore essential. However, the evidence for physical and non-physical health benefits of urban green space is unclear.
METHODS: A literature search of academic and grey literature was conducted for studies and reviews of the health effects of green space. Articles found were appraised for their relevance, critically reviewed and graded accordingly. Their findings were then thematically categorized.
RESULTS: There is weak evidence for the links between physical, mental health and well-being, and urban green space. Environmental factors such as the quality and accessibility of green space affects its use for physical activity. User determinants, such as age, gender, ethnicity and the perception of safety, are also important. However, many studies were limited by poor study design, failure to exclude confounding, bias or reverse causality and weak statistical associations.
CONCLUSION: Most studies reported findings that generally supported the view that green space have a beneficial health effect. Establishing a causal relationship is difficult, as the relationship is complex. Simplistic urban interventions may therefore fail to address the underlying determinants of urban health that are not remediable by landscape redesign.