The paradox of high greenness and poor health in rural Central Appalachia.

While many studies have found positive correlations between greenness and human health, rural Central Appalachia is an exception. The region has high greenness levels but poor health. The purpose of this commentary is to provide a possible explanation for this paradox: three sets of factors overwhelming or attenuating the health benefits of greenness. These include environmental (e.g., steep typography and limited access to green space used for outdoor recreation), social (e.g., chronic poverty, declining coal industry, and limited access to healthcare), and psychological and behavioral factors (e.g., perceptions about health behaviors, healthcare, and greenness). The influence of these factors on the expected health benefits of greenness should be considered as working hypotheses for future research. Policymakers and public health officials need to ensure that greenness-based interventions account for contextual factors and other determinants of health to ensure these interventions have the expected health benefits.

Nature connectedness connects the visibility of trees through windows and mental wellbeing: a study on the "3 visible trees" component of the 3-30-300 rule.

To examine the mediatory role of nature connectedness between tree visibility through windows and mental wellbeing, we conducted a questionnaire survey and examined the mediation effect using both cross-sectional and semi-longitudinal mediation models. We evaluated nature connectedness using the Inclusion of Nature in Self (INS) scale and the Connectedness to Nature Scale (CNS) and measured mental wellbeing using the WHO-5 wellbeing index. Our results showed that participants who could see at least three trees through their windows reported higher levels of both nature connectedness and mental wellbeing compared to those without such visibility. Nature connectedness significantly mediated the relationship between the visibility of trees through windows and mental wellbeing, albeit with a somewhat limited effect. More broadly, this study provides additional evidence in support of the "3" component of the 3-30-300 "rule" for equitable access to greenspace in cities.

Spatiotemporal non-stationarity in green space and stress relationships: Recent evidence from South Korea.

A growing body of literature has linked exposure to "green space" (vegetation-rich areas) and other forms of nature to mental health. Exposure-outcome associations at regional or national scales can overlook local associations that define how geographically distinct populations may experience nature differently. Large-scale results might downplay the importance of lived experiences and heterogeneity of human-nature relationships at local scales. The current study examines three types of vegetative cover and identifies how they are associated with perceived stress in South Korea during and before the COVID-19 pandemic. We find forest cover is consistently negatively associated with perceived stress at nationwide scales. In contrast, grass cover and the normalized difference vegetation index (NDVI) show mixed associations with perceived stress at nationwide scales. Models accounting for spatial and temporal variability demonstrate that associations of forest cover, grass cover, and NDVI with perceived stress varies across the country and the study's four-year time horizon. Local governments may need divergent urban greening strategies for health promotion that respond to their specific sociodemographic and pre-existing environmental conditions.

Is indoor and outdoor greenery associated with fewer depressive symptoms during COVID-19 lockdowns? A mechanistic study in Shanghai, China.

Increasing numbers of studies have observed that indoor and outdoor greenery are associated with fewer depressive symptoms during COVID-19 lockdowns. However, most of these studies examined direct associations without sufficient attention to underlying pathways. Furthermore, few studies have combined different types of indoor and outdoor greenery to examine their effects on the alleviation of depressive symptoms. The present study hypothesized that indoor and outdoor exposure to greenery increased the perceived restorativeness of home environments, which, in turn, reduced loneliness, COVID-related fears, and, ultimately, depressive symptoms. To test our hypotheses, we conducted an online survey with 386 respondents in Shanghai, China, from April to May 2022, which corresponded to strict citywide lockdowns that resulted from the outbreak of the Omicron variant. Indoor greenery measures included the number of house plants, gardening activities, and digital nature exposure as well as semantic image segmentation applied to photographs from the most viewed windows to quantify indoor exposure to outdoor trees and grass. Outdoor greenery measures included total vegetative cover (normalized difference vegetation index [NDVI]) within a 300 m radius from the home and perceived quality of the community's greenery. Associations between greenery and depressive symptoms/clinical levels of depression, as measured by the Patient Health Questionnaire-9 (PHQ-9), were examined using generalized linear and logistic regression models. Structural equation modeling (SEM) was used to test pathways between greenery exposure, restorativeness, loneliness, fear of COVID-19, and depressive symptoms. The results showed that: 1) indoor and outdoor greenery were associated with fewer depressive symptoms; 2) greenery could increase the restorativeness of the home environment, which, in turn, was associated with fewer COVID-related mental stressors (i.e., loneliness and fear of COVID-19), and ultimately depressive symptoms; and 3) gender, education, and income did not modify associations between greenery and depressive symptoms. These findings are among the first to combine objective and subjective measures of greenery within and outside of the home and document their effects on mental health during lockdowns. Comprehensive enhancements of greenery in living environments could be nature-based solutions for mitigating COVID-19 related mental stressors.

Do sex and gender modify the association between green space and physical health? A systematic review.

A growing literature shows that green space can have protective effects on human health. As a marginalized group, women often have worse life outcomes than men, including disparities in some health outcomes. Given their marginalization, women might have "more to gain" than men from living near green spaces. Yet, limited research has deliberately studied whether green space-health associations are stronger for women or men. We conducted a systematic review to synthesize empirical evidence on whether sex or gender modifies the protective associations between green space and seven physical health outcomes (cardiovascular disease, cancer, diabetes, general physical health, non-malignant respiratory disease, mortality, and obesity-related health outcomes). After searching five databases, we identified 62 articles (including 81 relevant analyses) examining whether such effect modification existed. We classified analyses based on whether green space-health were stronger for women, no sex/gender differences were detected, or such associations were stronger for men. Most analyses found that green space-physical health associations were stronger for women than for men when considering study results across all selected health outcomes. Also, women showed stronger protective associations with green space than men for obesity-related outcomes and mortality. Additionally, the protective green space-health associations were slightly stronger among women for green land cover (greenness, NDVI) than for public green space (parks), and women were also favored over men when green space was measured very close to one's home (0-500 m). Further, the green space-health associations were stronger for women than for men in Europe and North America, but not in other continents. As many government agencies and nongovernmental organizations worldwide work to advance gender equity, our review shows that green space could help reduce some gender-based health disparities. More robust empirical studies (e.g., experimental) are needed to contribute to this body of evidence.

Natural and built environments and blood pressure of Alpine schoolchildren.

BACKGROUND: Early life environments may influence children's blood pressure (BP), but evidence on the combined effects of natural and built environment exposures is scarce. The present study investigates the associations of natural and built environment indicators, traffic noise, and air pollution with BP in children living in Alpine valleys. METHODS: In 2004/2005, 1251 school children (8-12 years old) were sampled for a cross-sectional survey in several Austrian and Italian mountain valleys. Children's mothers completed a questionnaire. The outcomes of interest were systolic and diastolic BP measured with a calibrated oscillometric device. Indicators of land cover assigned to the residential and school coordinates within 100 and 1000 m included normalized difference vegetation index (NDVI), tree canopy cover, and a broader naturalness indicator titled distance to nature (D2N). The presence of a home garden was also measured via self-report. Imperviousness density served as a proxy for the built environment. Residential air pollution (NO2) and noise (Lden) from traffic were calculated using bespoke modeling. NO2, Lden, physical activity, and body mass index (BMI) were treated as mediating pathways. RESULTS: Higher NDVI and tree cover levels in residential and school surroundings and home gardens were consistently associated with lower BP. The built environment was associated with higher BP. Counterintuitive inverse associations between NO2 and Lden and BP were also found. Structural equation modeling showed that higher levels of greenspace and presence of a home garden were weakly associated with more outdoor play spaces, and in turn with lower BMI, and ultimately with lower BP. CONCLUSIONS: Exposure to natural environments may help maintain normal BP in children, while built environment may increase children's BP. Outdoor play and less adiposity in greener areas may mediate some of these associations. Evidence on air pollution and noise remains controversial and difficult to explain.

Associations of greenness surrounding schools with blood pressure and hypertension: A nationwide cross-sectional study of 61,229 children and adolescents in China.

BACKGROUND: Greenness exposure may lower blood pressure. However, few studies of this relationship have been conducted with children and adolescents, especially in low and middle-income countries. OBJECTIVES: To evaluate associations between greenness around schools and blood pressure among children and adolescents across China. METHODS: We recruited 61,229 Chinese citizens aged 6-18 years from 94 schools in a nationwide cross-sectional study in seven Chinese provinces/province-level municipalities. Participants' blood pressures and hypertension were assessed with standardized protocols. Greenness levels within 500 m and 1,000 m of each school were estimated with three satellite-based indices: vegetation continuous fields (VCF), normalized difference vegetation index (NDVI), and soil adjusted vegetation index (SAVI). Generalized linear mixed models were used to evaluate associations between greenness and blood pressure, greenness and prevalent hypertension, using coefficient and odds ratio respectively. Stratified analyses and mediation analyses were also performed. RESULTS: One interquartile range increase in greenness was associated with a 17%-20% reduced prevalence of hypertension for all measures of greenness (odds ratios for VCF500m = 20% (95% CI:18%, 23%); for NDVI500m = 17% (95% CI:13%, 21%); and for SAVI500m = 17% (95% CI: 13%, 20%). Increases in greenness were also associated with reductions in systolic blood pressure (0.48-0.58 mmHg) and diastolic blood pressure (0.26-0.52 mmHg). Older participants, boys, and urban dwellers showed stronger associations than their counterparts. No evidence of mediation was observed for air pollution (i.e., NO2 and PM2.5) and body mass index. CONCLUSION: Higher greenness around schools may lower blood pressure levels and prevalent hypertension among Chinese children and adolescents, particularly in older subjects, boys, and those living in urban districts. Further studies, preferably longitudinal, are needed to examine causality.

Greenspace and park use associated with less emotional distress among college students in the United States during the COVID-19 pandemic.

The COVID-19 pandemic has negatively affected many people's psychological health. Impacts may be particularly severe among socially vulnerable populations such as college students, a group predisposed to mental health problems. Outdoor recreation and visits to greenspaces such as parks offer promising pathways for addressing the mental health challenges associated with COVID-19. During the early stages of the pandemic (March-May 2020), we surveyed 1280 college students at four large public universities across the United States (U.S.) to assess how, and why, outdoor recreation and park use changed since the emergence of COVID-19. We also measured students' self-reported levels of emotional distress (a proxy for psychological health) and assessed potential demographic and contextual correlates of distress, including county-level per capita park area and greenness, using generalized linear models. We found that 67% of students reported limiting outdoor activities and 54% reported reducing park use during the pandemic. Students who reduced their use of outdoor spaces cited structural reasons (e.g., lockdowns), concerns about viral transmission, and negative emotions that obstructed active lifestyles. Students who maintained pre-pandemic park use levels expressed a desire to be outdoors in nature, often with the explicit goal of improving mental and physical health. Emotional distress among students was widespread. Models showed higher levels of emotional distress were associated with reducing park use during the pandemic and residing in counties with a smaller area of parks per capita. This study of U.S. college students supports the value of park-based recreation as a health promotion strategy for diverse populations of young adults during a time of crisis.

"Messy transitions": Students' perspectives on the impacts of the COVID-19 pandemic on higher education.

The COVID-19 pandemic affected every area of students' lives, especially their education. Limited research has explored students' experiences during the pandemic. This study documents how students across seven United States universities viewed the impact of the COVID-19 pandemic on their educational experiences and how these students reacted to these impacts. We present qualitative data from an online survey conducted between March and May 2020 that resulted in 1267 respondents with relevant data. Conventional content analysis with an inductive approach was used to analyze open-ended responses to the question, "We are interested in the ways that the coronavirus (COVID-19) pandemic has changed how you feel and behave. What are the first three ways that come to mind?" Six categories emerged from the data: changes in instruction delivery mode, changes in schedule and everyday life, increased technology use, decreased academic opportunities and resources, negative reaction to the changes in higher education, and positive reactions to changes in higher education. Among our recommendations for practice are personalized approaches to material delivery and evaluation, synchronous classes and opportunities to connect with professors and students, and convenient support services.

Allergic symptoms in association with naturalness, greenness, and greyness: A cross-sectional study in schoolchildren in the Alps.

BACKGROUND: Greenness may protect from or contribute to allergy risk by influencing air pollution and human-microbe interactions. However, existing research on the issue is heterogeneous and produced conflicting results. Less in known about the effects of greyness. This study investigated the association between different characteristics of residential and school environment and allergic symptoms in schoolchildren. METHODS: The present cross-sectional survey was undertaken in 2004/2005 among 1251 schoolchildren (8-12 years old) in several alpine valleys in Austria and Italy. Children's mothers completed a questionnaire that asked about allergic symptoms (International Study of Asthma and Allergies in Childhood questionnaire), sociodemographic information, lifestyle, perinatal data, and housing conditions. We constructed four aggregate outcome variables: current asthma symptoms, ever asthma symptoms, ever allergic rhinitis (AR) symptoms, and ever eczema symptoms. We employed well-known greenness and greyness exposure indicators (Normalized Difference Vegetation Index, tree canopy cover, agricultural cover, imperviousness cover, and industrial cover), as well as an alternative naturalness index (Distance to Nature, D2N). Adjusted logistic regressions were used to explore associations between each exposure-outcome pair. Air pollution (NO2), traffic noise and time spent outdoors were tested as potential mediators in causal mediation analysis. RESULTS: Decrease in naturalness in a 500-m buffer around the home was associated with higher prevalence of AR symptoms. Associations with asthma symptoms were in the same direction but marginally significant. Residential NDVI and tree cover were marginally associated with lower prevalence of asthma and AR symptoms. Having a domestic garden was associated with lower prevalence of asthma symptoms. School greenness in a 100-m buffer was associated with lower prevalence of AR symptoms. Residential greyness was associated with higher prevalence of AR and asthma symptoms. We observed stronger associations for greenness and greyness in non-movers and in children without a family history of allergies. Mediation by NO2 and time spent outdoors was present in some of the exposure-outcome pairs. CONCLUSIONS: Schoolchildren residing in places with lower naturalness and higher greyness may be more likely to have allergic rhinitis and possibly asthma. Considering more comprehensive indicators than greenness and greyness and conducting research in children without a family history of allergic diseases may be key to better understanding who can profit from natural landscapes.

Does greenery experienced indoors and outdoors provide an escape and support mental health during the COVID-19 quarantine?

BACKGROUND: The COVID-19 pandemic has profoundly changed people's ability to recreate in public green spaces, which is likely to exacerbate the psychological impacts of the pandemic. In the current study, we seek to understand whether greenery can support mental health even with insufficient outdoor exposure in times of physical isolation from the outdoor environment. METHODS: Between 17 May and 10 June, 2020, we conducted an online survey among 323 students (21.99 ± 3.10 years; 31% male) in health-related programs from two universities in the city of Plovdiv, Bulgaria. Severities of depressive and anxiety symptoms over the past two weeks were measured with the Patient Health Questionnaire 9-item and the Generalized Anxiety Disorder 7-item scale. We employed two self-reported measures of greenery experienced indoors (number of houseplants in the home and proportion of exterior greenery visible from inside the home) and two measures of greenery experienced outdoors (presence/absence of a domestic garden and availability of neighborhood greenery). Restorative quality of the home (the "being away" dimension of the Perceived Restorativeness Scale; PRS) and the neighborhood (the "being away" and "fascination" dimensions of the PRS), engagement with outdoor greenery (frequency of different types of interaction) and perceived social support were treated as mediators. Associations between greenery and mental health were tested using generalized linear regression and logistic regression. Structural equation modelling (SEM) techniques were used to test the theoretically-indicated relations among the variables. RESULTS: Clinically-meaningful symptoms of moderate depression and anxiety were reported by approximately 33% and 20% of the students, respectively. The relative abundance of greenery visible from the home or in the neighborhood was associated with reduced depressive/anxiety symptoms and lower depression/anxiety rates. Having more houseplants or a garden was also associated with some of these markers of mental health. As hypothesized, the mental health-supportive effects of indoor greenery were largely explained by increased feelings of being away while at home. Neighborhood greenery contributed to neighborhood restorative quality, which in turn facilitated social support and more frequent engagement with greenery, and that led to better mental health. CONCLUSIONS: Students who spent most of their time at home during the COVID-19 epidemic experienced better mental health when exposed to more greenery. Our findings support the idea that exposure to greenery may be a valuable resource during social isolation in the home. However, causal interpretation of these associations is not straightforward.

Analytical approaches to testing pathways linking greenspace to health: A scoping review of the empirical literature.

BACKGROUND: Inadequate translation from theoretical to statistical models of the greenspace - health relationship may lead to incorrect conclusions about the importance of some pathways, which in turn may reduce the effectiveness of public health interventions involving urban greening. In this scoping review we aimed to: (1) summarize the general characteristics of approaches to intervening variable inference (mediation analysis) employed in epidemiological research in the field; (2) identify potential threats to the validity of findings; and (3) propose recommendations for planning, conducting, and reporting mediation analyses. METHODS: We conducted a scoping review, searching PubMed, Scopus, and Web of Science for peer-reviewed epidemiological studies published by December 31, 2019. The list of potential studies was continuously updated through other sources until March 2020. Narrative presentation of the results was coupled with descriptive summary of study characteristics. RESULTS: We found 106 studies, most of which were cross-sectional in design. Most studies only had a spatial measure of greenspace. Mental health/well-being was the most commonly studied outcome, and physical activity and air pollution were the most commonly tested intervening variables. Most studies only conducted single mediation analysis, even when multiple potentially intertwined mediators were measured. The analytical approaches used were causal steps, difference-of-coefficients, product-of-coefficients, counterfactual framework, and structural equation modelling (SEM). Bootstrapping was the most commonly used method to construct the 95% CI of the indirect effect. The product-of-coefficients method and SEM as used to investigate serial mediation components were more likely to yield findings of indirect effect. In some cases, the causal steps approach thwarted tests of indirect effect, even though both links in an indirect effect were supported. In most studies, sensitivity analyses and proper methodological discussion of the modelling approach were missing. CONCLUSIONS: We found a persistent pattern of suboptimal conduct and reporting of mediation analysis in epidemiological studies investigating pathways linking greenspace to health; however, recent years have seen improvements in these respects. Better planning, conduct, and reporting of mediation analyses are warranted.

Could nature help children rise out of poverty? Green space and future earnings from a cohort in ten U.S. cities.

BACKGROUND: Growing up in poverty is associated with poor health, and the American Dream of upward mobility is becoming an illusion for many low-income children. But nearby green space can support academic achievement, creativity, and emotional regulation, and these traits might help children rise out of poverty. OBJECTIVES: To examine the relationship between recent incomes of children born into poverty in the ten largest U.S. cities and densities of residential green space during childhood. METHODS: We calculate park proximity, park acreage, new park development, and NDVI greenness for 1980-1990 from Landsat and Trust for Public Land data. We obtain the 2014 income for children born between 1978 and 1982 into families in poverty from The Opportunity Atlas cohort, aggregated at the tract level (n = 5849). RESULTS: Conditional autoregressive (CAR) models of tracts show statistically significant associations between income rank and above-average levels of greenness but not between income rank and park measures, adjusting for individual and neighborhood confounders and spatial autocorrelation. We estimate that, over a 30-year career, children growing up in tracts with the most vegetative cover will earn cumulatively $28,000 more than children growing up in tracts with the least cover, on average. Tracts with lower than average levels of precipitation, higher disadvantage, higher population density, or higher annual temperatures do not show beneficial effects of green space. CONCLUSIONS: Greenness may be weakly associated with children rising out of poverty in wetter, cooler, less-dense, more advantaged census tracts.

Human-Nature Relationships and Normative Beliefs Influence Behaviors that Reduce the Spread of Aquatic Invasive Species.

Human behaviors that contribute to the spread of aquatic invasive species are influenced by myriad social psychological factors that vary across contexts and populations. Understanding such behavior is crucial for forming successful management strategies that minimize environmental impacts while generating support and cooperation among stakeholders. We identify several reasons why recreational anglers and boaters make decisions that benefit the environment. Specifically, our study addresses the following objectives: (1) examine reported behaviors that minimize the spread of aquatic invasive species, (2) test the effects of social normative beliefs on reported behaviors, and (3) determine the role of human-nature relationships in explaining behavioral patterns. Drawing on a path model of the decisions made by respondents who completed an on-site survey at two nature-based case study sites in Illinois, we observed that reported behavior was positively influenced by normative beliefs about those behaviors and human-nature relationships. Specifically, the Participant in Nature and Partner with Nature orientations were positively and negatively correlated with norms, respectively. In turn, norms positively predicted reported stewardship behaviors. These findings advance research on the human dimensions of aquatic invasive species by providing insights on the role of stable psychological processes that shape behavior, while informing management decisions aimed at minimizing biological invasions in freshwater ecosystems.

Correction to: Human-Nature Relationships and Normative Beliefs Influence Behaviors that Reduce the Spread of Aquatic Invasive Species.

The original article was published with few incorrect contexts.

Can pre-visit exposure to virtual tours of healthcare facilities help reduce child and parent anxiety during outpatient surgical procedures?

AIM: The study aims to evaluate the impact of exposure to a highly realistic virtual facility tour prior to the on-site visit on patients and their parent/care partner's self-reported anxiety and physiological measures on the day of the procedure. BACKGROUND: Preoperative anxiety impacts pediatric surgical outcomes; therefore, it is important for healthcare providers to address and manage preoperative anxiety in pediatric patients to promote better outcomes and overall wellbeing. Providing patients with a preview of the care setting before the actual procedure can be highly beneficial in mitigating preoperative anxiety. METHODOLOGY: In this pilot randomized experimental study, sixteen patient-care partner dyads scheduled to undergo a gastrointestinal procedure either received a virtual tour identical to the places experienced on the day of the procedure (experimental group) or received no virtual tour (control group). Self-reported measures of anxiety were collected from participants before and on the day of the procedure. Physiological measures of heart rate variability and skin conductance were collected on the day of the procedure from both groups. RESULTS: There were no significant differences between the self-reported and physiological measures of anxiety between the child groups. However, parents in the control group reported lower levels of anxiety and demonstrated lower levels of stress based on their physiological measures. CONCLUSION: Exposure to virtual facility tours days before the surgery was not helpful in positively impacting the psychological measures related to preoperative anxiety levels for the participants.

Testing the mediatory role of kinesiophobia in the association between perceived greenspace and physical activity among individuals with chronic low back pain.

To test the mediatory role of kinesiophobia between greenspace and physical activity, we conducted a cross-sectional survey and recruited 801 participants with chronic low back pain. The level of greenspace was assessed using both perceived greenspace and the Normalized Difference Vegetation Index (NDVI). The frequency of walking and moderate and vigorous physical activities was measured using a brief assessment, while kinesiophobia was evaluated using the 11-item Tampa Scale for Kinesiophobia (TSK-11). The results revealed that perceived greenspace was positively associated with all measured physical activities, and was negatively associated with kinesiophobia. Meanwhile, NDVI was only positively associated with moderate and vigorous physical activity. Kinesiophobia played a marginal but significant mediating role in the association of perceived greenspace with walking, moderate physical activity, and vigorous physical activity. In conclusion, our findings offer early evidence of associations and pathways between greenspace and physical activity among individuals with chronic low back pain.

Leveraging and exercising caution with ChatGPT and other generative artificial intelligence tools in environmental psychology research.

Generative Artificial Intelligence (GAI) is an emerging and disruptive technology that has attracted considerable interest from researchers and educators across various disciplines. We discuss the relevance and concerns of ChatGPT and other GAI tools in environmental psychology research. We propose three use categories for GAI tools: integrated and contextualized understanding, practical and flexible implementation, and two-way external communication. These categories are exemplified by topics such as the health benefits of green space, theory building, visual simulation, and identifying practical relevance. However, we also highlight the balance of productivity with ethical issues, as well as the need for ethical guidelines, professional training, and changes in the academic performance evaluation systems. We hope this perspective can foster constructive dialogue and responsible practice of GAI tools.

Greenspace and human microbiota: A systematic review.

BACKGROUND: Potential effect of greenspace exposure on human microbiota have been explored by a number of observational and interventional studies, but the results remained mixed. We comprehensively synthesized these studies by performing a systematic review following Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. METHODS: Comprehensive literature searches in three international databases (PubMed, Embase, and Web of Science) and three Chinese databases (China National Knowledge Infrastructure, Wanfang, and China Biology Medicine disc) were conducted from inception to November 1, 2023. Observational and interventional studies that evaluated associations between greenspace exposure and human microbiota at different anatomical sites were included. Studies were assessed using the National Toxicology Program's office of Health Assessment and Translation risk of bias tool and certainty of evidence was assessed using the Grading of Recommendations, Assessment, Development and Evaluation framework. Two authors independently performed study selection, data extraction, and risk of bias assessment, and evidence grading. Study results were synthesized descriptively. RESULTS: Twenty studies, including 11 observational studies and 9 interventional studies, were finally included into the systematic review. The microbiota of the included studies was from gut (n = 13), skin (n = 10), oral cavity (n = 5), nasal cavity (n = 5) and eyes (n = 1). The majority of studies reported the associations of greenspace exposure with increased diversity (e.g., richness and Shannon index) and/or altered overall composition of human gut (n = 12) and skin microbiota (n = 8), with increases in the relative abundance of probiotics (e.g., Ruminococcaceae) and decreases in the relative abundance of pathogens (e.g., Streptococcus and Escherichia/Shigella). Due to limited number of studies, evidence concerning greenspace and oral, nasal, and ocular microbiota were still inconclusive. CONCLUSION: The current evidence suggests that greenspace exposure may diversify gut and skin microbiota and alter their composition to healthier profiles. These findings would be helpful in uncovering the potential mechanisms underlying greenspace and human health and in promoting a healthier profile of human microbiota.

Impact of green space and built environment on metabolic syndrome: A systematic review with meta-analysis.

Metabolic Syndrome presents a significant public health challenge associated with an increased risk of noncommunicable diseases such as cardiovascular conditions. Evidence shows that green spaces and the built environment may influence metabolic syndrome. We conducted a systematic review and meta-analysis of observational studies published through August 30, 2023, examining the association of green space and built environment with metabolic syndrome. A quality assessment of the included studies was conducted using the Office of Health Assessment and Translation (OHAT) tool. The Grading of Recommendations, Assessment, Development, and Evaluations (GRADE) assessment was used to evaluate the overall quality of evidence. Our search retrieved 18 studies that met the inclusion criteria and were included in our review. Most were from China (n = 5) and the USA (n = 5), and most used a cross-sectional study design (n = 8). Nine studies (50 %) reported only green space exposures, seven (39 %) reported only built environment exposures, and two (11 %) reported both built environment and green space exposures. Studies reported diverse definitions of green space and the built environment, such as availability, accessibility, and quality, particularly around participants' homes. The outcomes focused on metabolic syndrome; however, studies applied different definitions of metabolic syndrome. Meta-analysis results showed that an increase in normalized difference vegetation index (NDVI) within a 500-m buffer was associated with a lower risk of metabolic syndrome (odds ratio [OR] = 0.90, 95%CI = 0.87-0.93, I2 = 22.3 %, n = 4). A substantial number of studies detected bias for exposure classification and residual confounding. Overall, the extant literature shows a 'limited' strength of evidence for green space protecting against metabolic syndrome and an 'inadequate' strength of evidence for the built environment associated with metabolic syndrome. Studies with more robust study designs, better controlled confounding factors, and stronger exposure measures are needed to understand better what types of green spaces and built environment features influence metabolic syndrome.