Nature exposure and mental health during the COVID-19 pandemic: A Navigation Guide systematic review with meta-analysis

Abstract

Previous reviews concluded that nature contact was an important coping strategy against poor mental health during the COVID-19 pandemic. However, the quality of evidence in these reviews was not sufficiently documented in terms of the risk of bias in reviewed studies. We attempted to fill this gap with a Navigation Guide systematic review and meta-analyses on the associations between nature exposure and mental health during the pandemic. Searches in PubMed, Web of Science, Scopus, CINAHL, and PsycInfo retrieved relevant articles published between January 1, 2020, and April 30, 2022. Included studies reported observational findings from human participants with indoor or outdoor nature exposure and measures of mental health. We used the Navigation Guide methodology to assess the risk of bias and quality of evidence across the body of evidence for each mental health outcome. A total of 4,464 articles were initially identified. After the screening, 59 were ultimately included. Studies reported diverse variables of nature availability, green space visit frequency, green space accessibility, and green space type (e.g., indoor vs. outdoor) with 12 mental health outcomes. Meta-analyses found access to gardens was associated with lower odds of depression (OR=0.71, 95% CI=0.61-0.82, I2=0%, n=3) and anxiety (OR=0.73, 95% CI=0.63-0.84, I2=0%, n=2). Higher frequency of visits to greenspace during the COVID-19 pandemic was associated with improved mental well-being (OR=0.10, 95% CI=0.07-0.14, I2=0%, n=2) and general mental health (OR=0.11, 95% CI=0.03-0.38, I2=82%, n=2). The quality of evidence was “very low” for all outcomes, and high levels of bias and between-study heterogeneity were observed in the studies of nature exposure and mental health (41% of studies had high, 24% probably high, and 35% had a low risk of bias). Nonetheless, given trends observed in the results, nature-based infrastructure that emphasizes exposure to nearby nature may have promoted psychological resilience during this public health crisis.