Green and blue space exposure and non-communicable disease related hospitalizations: A systematic review

The global increase in non-communicable diseases (NCDs) presents a critical public health concern. Emerging evidence suggests that exposure to natural environments may reduce the risk of developing NCDs through multiple pathways. The present systematic review aims to synthesize and evaluate the observational evidence regarding associations between exposure to green and blue spaces and hospital admissions related to NCDs. A comprehensive literature search strategy was conducted in Embase (Ovid), PubMed, and Web of Science. The risk of bias and quality of the evidence were assessed using The Navigation Guide methodology, an approach specifically designed for environmental health research. Of 3060 search results, 17 articles were included. Notably, the majority of the studies (n = 14; 82.4%) were published from 2020 onwards. Most studies were conducted in the United States (n = 6; 35.3%) and China (n = 4; 23.5%). Exposure to green spaces was assessed through all studies, while only three included blue spaces. In terms of study design, cohort design was employed in nearly half of the studies (n = 8; 47.1%), followed by case-crossover design (n = 3, 17.6%). Over 75% of the included studies (n = 13) had a high or probably high rating in the risk of bias assessment. The studies encompassed diverse NCD outcome domains; cardiovascular diseases (CVDs) (n = 10), respiratory diseases (RSDs) (n = 2), heat-related diseases (n = 1), metabolic diseases (n = 2), cancer (n = 1), neurodegenerative diseases (NDDs) (n = 2), and mental health disorders (n = 2). The present review suggests that a clear link between blue space exposure and NCD hospital admissions is not evident. However, exposure to green spaces appears to predominantly have a protective effect, although the direction of the association varies across different outcome domains. The heterogeneity among the outcome domains together with the limited number of studies, emphasizes the need for more robust evidence.

Does exposure to greenness improve children's neuropsychological development and mental health? A Navigation Guide systematic review of observational evidence for associations

BACKGROUND

Contact with nature may have a key role in child brain development. Recent observational studies have reported improvements in children's neuropsychological development and mental health associated with greenness exposure. In a rapidly urbanizing word, researchers, policymakers, healthcare workers and urban planners need to work together to elaborate evidence-based policies and interventions to increase the availability of quality green space with the potential to enhance childhood development.

OBJECTIVE

To review the observational evidence assessing the effect of exposure to greenness on children's neuropsychological development and mental health.

METHODS

The protocol for the review was preregistered at PROSPERO (CRD42020213838). The Navigation Guide systematic review methodology was followed. Search strategies were formulated and adapted to each database. Searches were performed in PubMed, Scopus, Web of Science and EBSCO's GreenFILE on October 5, 2021. Additional articles were further identified by hand-searching reference lists of included papers.

RESULTS

A systematic search of 4 databases identified 621 studies, of which 34 were included in the review. The studies included investigated diverse domains within neuropsychological development and mental health, such as attention, working memory, intelligence, cognitive development, academic performance, well-being, attention-deficit/hyperactivity disorder symptoms, and behavior. Most of the studies were rated as having high or probably high risk of bias in the assessment.

DISCUSSION

Although nearly all studies showed a positive association between greenness exposure and the outcomes studied, the heterogeneity in the methods used to assess exposure and the diversity of domains within each main outcome has made it difficult to draw clear conclusions. Future studies should adopt a longitudinal design to confirm the causality of the associations and include measures to determine which characteristics of greenness have the greatest influence on each domain. Researchers should also try to explore pathways linking exposure to greenness with the neuropsychological development and mental health, by implementing mechanistic studies.