Green space exposure on depression and anxiety outcomes: A meta-analysis

The development of urbanization has led to emerging mental health issues. Green space was becoming increasingly important for mental health. Previous studies have demonstrated the value of green space for a variety of outcomes connected to mental health. However, uncertainty remains regarding the association between green spaces and the risk of depression and anxiety outcomes. This study aimed to integrate present evidence from observational studies to define the association of exposure to green space with depression and anxiety.A thorough electronic search of PubMed, Web of Science and Embase database was performed. We transformed the odds ratio (OR) of different green increments into per 0.1 unit increase in normalized difference vegetation index (NDVI) and per 10% increase in percentage of green space. Cochrane's Q and I2 statistics were used to assess study heterogeneity, and random-effects models were employed to calculate combined effect estimation OR with 95% confidence intervals (CIs). Pooled analysis was completed using Stata 15.0.According to this meta-analysis, a 10% increase in the proportion of green space was linked to a lower risk of depression (merged OR (95% CI) = 0.963 (0.948, 0.979)) and anxiety (merged OR (95% CI) = 0.938 (0.858, 1.025)) and a 0.1 unit increase in NDVI was linked to a lower risk of depression (merged OR (95% CI) = 0.931 (0.887, 0.977)).Results of this meta-analysis supported improving green space exposure in preventing depression and anxiety. Higher green space exposure might be helpful for depression and anxiety disorders. Therefore, improving or preserving green space should be regarded as a promising intervention for public health.