Blue spaces support human health through physical activity, restoration, and environmental factorsScientific research has established that blue spaces, such as oceans, lakes, and rivers, contribute to human health. However, researchers have not established the specific mechanisms by which blue spaces impact people’s health in positive ways. This systematic literature review and meta-analysis summarized the existing scientific evidence and statistically evaluated four potential pathways through which blue spaces might improve health outcomes: physical activity, restoration, social interaction, and environmental factors. According to the authors, no other literature review has synthesized or evaluated the evidence for these four mechanisms, or pathways. Therefore, this research synthesis could be useful for city planners who are trying to create sustainable and healthy urban environments.
This literature review followed guidelines for a systematic review of relevant quantitative studies published in major scientific databases. The authors, based in the UK, systematically selected relevant studies and used a standard template to collect key information from each study, including its population, age, sample size, design, main results, measures, and confounding variables. Researchers then evaluated the quality and potential bias of individual studies using a standardized tool and then conducted meta-analyses of studies with blue space exposure measures and health outcomes that were appropriate to combine and test statistically. This procedure enabled them to evaluate the effects of 3 of the 4 proposed pathways statistically—the physical activity, restoration, and social interaction mechanisms. The researchers did not identify enough appropriate studies of environmental factors to conduct a statistical meta-analysis of that potential pathway.
This systematic review process yielded 50 quantitative studies of blue spaces’ effects on human health measures—27 of which were appropriate for statistical meta-analyses. Of those, 18 articles examined associations between blue space exposure and physical activity. These studies generally linked living closer to blue spaces with more physical activity; however, a few studies noted negative associations or non-statistically significant relations between blue space exposure and physical activity. Meta-analyses calculated the effects of distance from blue spaces and size of blue spaces on physical activity: both living closer to blue spaces and larger amounts of blue spaces were associated with low but statistically significant increases in physical activity. Twenty-one articles examined associations between blue space exposure and restoration, including 18 which reported positive associations and 3 which reported no associations. Meta-analyses of these restoration studies linked increases in the amount of blue space to small-to-moderate increases in restoration; living closer to blue spaces was not associated with more restoration, but more contact with blue spaces was associated with restoration. Seven studies examined social interaction as a pathway through which blue space exposure might improve health. With a few exceptions, these studies linked exposure to blue space to increased social interaction, including increased time with family or friends, social cohesion, sense of community, and neighborhood attachment. At the same time, meta-analysis of the three appropriate social interaction studies found that living closer to blue space was not associated with increased social interaction. Fourteen articles investigated relationships between blue space exposure and environmental factors. These studies generally found positive relationships between blue space exposure and environmental factors, such as lower heat indices and temperatures and higher air quality around water sources; however, individual articles reported negative effects, such as increased air pollution and disease transmission, near some water sources studied.
Overall, this review synthesized existing evidence which largely indicates that blue space exposure increases physical health, enhances restoration, and improves environmental factors. Therefore, three of the four hypothesized pathways are supported by empirical evidence. Blue spaces also may have beneficial effects on social interaction; however, the empirical evidence is mixed, and this hypothesized pathway was not supported by the statistical meta-analysis. Empirical studies mostly linked more blue space exposure to better environmental indicators, but this existing literature did not lend itself to statistical meta-analysis. Based on this evidence, the researchers contend that blue spaces can address public health concerns faced by a growing urban population. That is, creating more blue spaces and promoting more engagement with blue spaces could counteract many negative effects of urban living and restore human health.
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