Links between green space and public health: a bibliometric review of global research trends and future prospects from 1901 to 2019

Considerable specific cross-sectional and review studies have linked exposure to green spaces to improving public health, but there is no bibliometric review attempting to systemically and retrospectively analyze these existing articles. Here we aim to uncover global research status, trends, and future prospects in green spaces and health (G-H) research then propose a framework for the underlying mechanisms and pathways that link green space to public health. We obtained 18 961 G-H research publications from the core Web of Science collection from 1901 to 2019, analyzing the characteristics of publication outputs, key scientific disciplines, and differences in performance between countries and institutions. Besides, content analysis was conducted to analyze the keywords, including keyword co-occurrence analysis and keyword clustering analysis. We found: (1) a steady quantitative increase in publications, active journals, and involved countries and institutions since the 1990s; (2) a significant increase and changes in G-H related interdisciplinary categories, with environment-related disciplines becoming the mainstream; (3) research focus and trends that were identified based on the analysis of high-frequency co-occurring keywords; (4) three main knowledge domains, namely, green spaces and physical health, mental health, and ecosystem health, that were identified and visualized based on keyword clustering analysis; (5) a framework of underlying mechanisms and pathways linking green space to public health that is proposed based on visualization of the three main knowledge domains. We suggest that the main challenge of G-H research is to further clarify in-depth the underlying mechanisms and pathways from multiple perspectives, including multiple nations, disciplines, and study designs. The lack of co-occurring keywords and clustering information related to social well-being suggests that research related to ‘social health’ is lacking. Based on a clear understanding of the quantity, quality, and characteristics of green space for public health, a health-based environmental plan should be proposed in the future.