Impacts of green space interventions in educational settings on children and young people's mental wellbeing: a systematic review

In the context of a recent decline in mental wellbeing in children and young people, there is increasing policy and practice interest in the benefits of childrens engagement with the natural environment to improve mental wellbeing. Although there is a growing evidence base linking health outcomes across populations with exposure to nature, the evidence base for the health, wellbeing and educational attainment benefits of green space interventions in children and adolescents is of lower quality. The aim of this systematic review was to assess whether the current evidence enables us to draw conclusions about the relationship between different educational green space intervention types and different categories of mental wellbeing outcome. The review adopted an approach to mental wellbeing grounded in the field of positive psychology, which sees wellbeing as a positive resource, composed of emotional, psychological and social domains. A number of outcomes was grouped in each domain, for example attention and executive function skills were grouped in the psychological wellbeing domain. Green space interventions were categorised into five sub-types: environmental education, break-time or play in a green environment, school gardening, learning in nature and nature pre-school/forest school. Extensive searches of seven databases, updated in March 2024, identified 36 quantitative studies, including quantitative components of mixed-methods studies. Study quality was assessed using the EPHPP tool. Due to study heterogeneity, meta-analysis was not feasible; instead, a Synthesis Without Meta-analysis (SWiM) based on effect direction was performed; additionally, a narrative synthesis summarising the effect direction at study level was conducted where an outcome was only measured within a single study within the same intervention category. Out of 37 reports of 36 studies, two had a strong overall rating, ten had a moderate quality rating and 25 had a weak overall rating. Based on generally very low certainty of evidence, there was some evidence for the positive effects of environmental education and breaks in green spaces on emotional wellbeing outcomes; for beneficial effects of breaks in green spaces on social wellbeing outcomes; and for improved outcomes in particular categories of psychological wellbeing associated with breaks in green spaces, learning in nature and forest school. Weaknesses identified in studies were often linked to specific features in study design, such as intervention dilution, as well as to lack of sensitivity of measurement instruments. This is the first comprehensive systematic review aiming to assess the effects of green space interventions in educational settings on outcomes across all three dimensions of mental wellbeing in children and young people aged 0-18. Recommendations are made on how study design can be improved in order to generate a stronger evidence base, including by having separate control groups, using a larger exposure dose and duration, extending the length of follow-up, and designing more nuanced interventions.