The effect of place-based nature interventions on human health: A systematic review

Although increasing evidence highlights the health benefits of living near green environments, little research has focused on physical interventions that increase the provision of greenspace. City, park, school, and forest managers are in need of program and practice guidance with health endpoints in mind.

We conducted a systematic review of longitudinal evaluations of place-based greening interventions and their effects on health outcomes or behaviors. Included studies evaluated the effects of changes in outdoor spaces intended to increase the quantity, quality, or accessibility of greenspace on a quantitatively assessed human health outcome or behavior.

We screened 18,831 unique citations for inclusion and included 98 manuscripts. Studies examined interventions including park improvements, garden creation, greenway construction, tree planting, and vacant lot greening. Studies varied widely in quality. Few studies applied randomized designs, and many did not adequately address confounding. Outcomes related to physical activity, body mass index, and dietary quality were frequently examined across studies. However, meta-analysis was not feasible due to high heterogeneity in outcome measurements. Findings suggest that park projects that included community engagement were more likely to improve physical activity than those that did not; school garden projects were inconsistent in improving students' diet; vacant lot greening projects consistently reported reductions in violent crime; new trail and greenway constructions did not appear to improve physical activity levels; and home garden projects tended not to improve dietary quality but did improve food security in some contexts.

While the number of studies and the quality of evidence remains low, there is some support for the value of place-based greenspace interventions for public health. Researchers should coordinate with community stakeholders before starting greening projects to develop evaluation strategies. Improved evaluation work could develop causal evidence to direct cities and community groups in effective greening projects.