The influence of freshwater blue spaces on human health and well-being:A systematic review based on assessment method

An increasing number of studies have explored the positive effects of blue spaces on human health, much of which involves the impacts of various blue space exposures on human health indicators, recognizing that the diversity in assessment methods may influence the final results. However, there are currently few systematic reviews that comprehensively synthesize this evidence. Additionally, current reviews in this field predominantly focus on coastal environments, while Freshwater Blue Spaces(FBS)receive less attention. Given that more than 50% of the global population lives within 3 km of freshwater bodies, it is crucial to understand the health impacts of these unique environments. Therefore, this study aims to systematically review the existing literature on the effects of FBS on human health and identify knowledge gaps. We systematically reviewed 34 articles following the PRISMA protocol. The results showed six main FBS exposure assessment methods and ten related health indicators. Additionally, we identified 74 health indicators and their relation to FBS exposure assessments. Our findings revealed: (i) FBS exposure assessment methods are becoming more diverse and refined, but challenges and limitations persist in their application; (ii) the studies employed a range of health indicators to explore different dimensions of human health, yet significant differences exist in their focus and methodologies; (iii) The results on the association between FBS and health exhibit heterogeneity, which not only depends on the health focus and indicators of each study but is also related to the exposure assessment methods used, the characteristics of FBS, sample differences, and the rigor of bias evaluation and control of confounding factors. Based on our findings, we propose a series of recommendations to further investigate the intrinsic connections between FBS and human health, providing opportunities to enhance human health and well-being.