Exposure to blue space surroundings and depressive symptoms in young Chinese adults: The mediating role of sleep

OBJECTIVE

Existing evidence suggests that the natural environment can influence mental health. However, limited research has focused on the relationship between blue space and depressive symptoms in young adults. To investigate the association between blue space surroundings and depressive symptoms in young adults in China and explore the underlying mechanisms.

METHODS

The study was conducted between September and November 2019, including 2,743 young adults from China. We assessed the exposure to blue space around participants' living environments during June, July, and August 2019 using the Modified Normalized Difference Water Index (MNDWI). Blue indexes were calculated for 300 m, 1000 m, and 3000 m circular buffer zones near residential environments. Logistic regression models were employed to explore the associations between blue space exposures (quartiles) and depressive symptoms, exploring potential mechanisms through structural equation modeling (SEM), while accounting for potential confounders. Stratification analysis was used to identify sensitive populations.

RESULTS

Depressive symptoms were found in 148 (5.3%) of the 2,743 young adults in the study. We observed a negative correlation between depressive symptoms and average MNDWIs at participants' addresses (OR: 0.84; 95%CI: 0.72-0.98), within 300m (OR: 0.81; 95%CI: 0.70-0.95), 1000m (OR: 0.80; 95%CI: 0.69-0.93), and 3000m (OR:0.77; 95%CI: 0.66-0.89) buffer zones. Within the 1000m buffer zone, sleep was found to mediate 21% of the relationship between the presence of blue space and depressive symptoms. The stratified analysis revealed a stronger association between low MNDWI levels within the 1000m buffer zone and depressive symptoms in females (P < 0.05). Additionally, average MNDWI levels within the 3000m buffer zone were associated with depressive symptoms in both females and males.

CONCLUSIONS

Blue space could improve depressive symptoms, particularly in females, with sleep playing a mediating role. Incorporating blue spaces into environmental planning is important for improving mental health.

The impact of outdoor blue spaces on the health of the elderly: A systematic review

Research on natural health has identified the potential benefit of outdoor blue spaces for human health and wellbeing. However, the existing evidence has relatively limited attention to the elderly. This study aims to review the available evidence on outdoor blue spaces and health outcomes among older individuals and identify knowledge gaps. In accordance with the PRISMA guidelines, specific keywords were used to search for articles published in English from inception to October 2023. Five databases (Scopus, PubMed, Web of Science, CINAHL, and PsycINFO) were searched, and 22 studies were identified in this review. We classified articles based on elderly health as general health (e.g., self-reported, perceived health and wellbeing), physical health (e.g., physical activity, physical function index), and mental health and wellbeing (e.g., depression). The findings indicated a positive correlation between outdoor blue space and the health of the elderly. In terms of the characteristics of exposure to outdoor blue spaces, direct contact (e.g., sensory-based) has not been well documented compared to indirect contact (e.g., distance, percentage, region-based). Although encouraging, the available body of evidence is limited and lacks consistency. Future research is needed to provide complementary evidence between outdoor blue spaces and elderly health.

Amount of and proximity to blue spaces and general health among older Chinese adults in private and public housing: A national population study

A growing body of research indicates that exposure to outdoor blue spaces is associated with better physical and mental health. However, few studies have explored the associations between different blue space indicators (e.g., amount of and proximity to freshwater and seawater) and general health. Moreover, research has rarely attempted to address the residential selection bias associated with the salutogenic effect of access to blue spaces. Therefore, this study explores the associations between the amount (percentage of blue space within a 1 km circular buffer) of and proximity (Euclidean distance to the edge of the nearest blue space) to blue space and older adults' general health across the entire country of China using the micro-data sample of one-percent national population sample survey in 2015. It adds to the existing literature by taking into account the neighbourhood selection mechanism for different housing tenures and examining the salutogenic effect of blue spaces separately for public housing residents and private housing residents. The results indicated that greater neighbourhood seawater coverage and living near a coastline were associated with better general health among older adults in both private and public housing, while the percentage of freshwater blue spaces within neighbourhoods and the distance to freshwater blue spaces were associated with better general health among private housing residents only. The blue spaces-general health associations were stronger among urban participants, participants in deprived neighbourhoods, males, participants aged under 80 years, and low- and medium-educated participants. Our findings indicated that living near the coast was beneficial to older adults' health, and residential selection bias confounded the association between freshwater blue spaces and health.

Simulated nature and positive body image: A comparison of the impact of exposure to images of blue and green spaces

Previous research has shown that exposure to simulated natural environments, such as still images and film, promotes more positive state body image. However, this body of work has not distinguished between different types of natural environment, with the distinction between blue and green spaces being notable. Here, we asked a sample of 168 university students from the United Kingdom to complete a measure of state body appreciation before and after being randomly assigned to one of three groups in which they viewed images of blue spaces, green spaces, or built environments, respectively. A mixed analysis of variance showed that exposure to images of the natural environments, but not the built environments, significantly elevated state body appreciation. In addition, exposure to images of blue spaces had a stronger effect on state body appreciation than exposure to images of green spaces. These results replicate previous work showing that exposure to simulated natural environments promotes more positive state body image, but additionally shows that blue spaces may be more effective than green spaces. Implications of the present findings for the development of imagery-based interventions aimed at promoting healthier body image are discussed.

Hotel attributes and overall customer satisfaction: What did COVID-19 change?

The effect of hotel attributes on customer satisfaction has been well studied in hospitality literature. However, the importance of hotel attributes for customer satisfaction may change due to the prevailing global pandemic given (1) the negative health consequences of the disease, (2) the guidelines and advisories issued by health agencies, and (3) wide media coverage of the pandemic. These factors can affect the importance that customers attach to different attributes. To date, there have been no studies analyzing these changes, and this study fills the gap by conducting a structural topic modeling-based analysis of hotel reviews before and during the pandemic. The results contribute to the literature by identifying new attributes and providing concrete evidence that attribute prevalence has changed in response to the pandemic. The results also lead to practical recommendations for increasing customer satisfaction in the hospitality industry during the prevailing disaster.

Perceived and objective availability of green and blue spaces and quality of life in people with dementia: results from the IDEAL programme

PURPOSE

The aim of this study was to investigate the associations between quality of life and both perceived and objective availability of local green and blue spaces in people with dementia, including potential variation across rural/urban settings and those with/without opportunities to go outdoors.

METHODS

This study was based on 1540 community-dwelling people with dementia in the Improving the experience of Dementia and Enhancing Active Life (IDEAL) programme. Quality of life was measured by the Quality of Life in Alzheimer's Disease (QoL-AD) scale. A list of 12 types of green and blue spaces was used to measure perceived availability while objective availability was estimated using geographic information system data. Regression modelling was employed to investigate the associations of quality of life with perceived and objective availability of green and blue spaces, adjusting for individual factors and deprivation level. Interaction terms with rural/urban areas or opportunities to go outdoors were fitted to test whether the associations differed across these subgroups.

RESULTS

Higher QoL-AD scores were associated with higher perceived availability of local green and blue spaces (0.82; 95% CI 0.06, 1.58) but not objective availability. The positive association between perceived availability and quality of life was stronger for urban (1.50; 95% CI 0.52, 2.48) than rural residents but did not differ between participants with and without opportunities to go outdoors.

CONCLUSIONS

Only perceived availability was related to quality of life in people with dementia. Future research may investigate how people with dementia utilise green and blue spaces and improve dementia-friendliness of these spaces.

Blue space, health and well-being: A narrative overview and synthesis of potential benefits

Research into the potential health and well-being benefits from exposure to green spaces such as parks and woodlands has led to the development of several frameworks linking the different strands of evidence. The current paper builds on these to provide a model of how exposure to aquatic environments, or blue spaces such as rivers, lakes and the coast, in particular, may benefit health and well-being. Although green and blue spaces share many commonalities, there are also important differences. Given the breadth of the research, spanning multiple disciplines and research methodologies, a narrative review approach was adopted which aimed to highlight key issues and processes rather than provide a definitive balance of evidence summary. Novel aspects of our framework included the inclusion of outcomes that are only indirectly good for health through being good for the environment, the addition of nature connectedness as both a trait and state, and feedback loops where actions/interventions to increase exposure are implemented. Limitations of the review and areas for future work, including the need to integrate potential benefits with potential risks, are discussed.

Physical and mental health effects of repeated short walks in a blue space environment: A randomised crossover study

INTRODUCTION

Blue spaces may benefit mental health and promote physical activity, although the evidence is still scarce. And benefits on physical health are less consistent. The objective of this randomized crossover study was to assess psychological and cardiovascular responses to blue spaces' exposure.

METHODS

A sample of 59 healthy adult office workers was randomly assigned to a different environment (i.e. blue space, urban space, and control site) on 4 days each week, for 3 weeks. For 20 min per day, they either walked along a blue or an urban space or rested at a control site. Before, during and/or after the exposure, we measured self-reported well-being and mood, blood pressure, and heart rate variability parameters. For well-being, we also assessed the duration of these potential effects over time (at least 4 h after exposure).

RESULTS

We found significantly improved well-being and mood responses immediately after walking in the blue space compared with walking in the urban space or when resting in the control site. Cardiovascular responses showed increased activity of the sympathetic nervous system, both during and after walking along the blue and urban spaces. However, cardiovascular responses measured after the walks, showed no statistically significant differences between the blue and the urban space environments.

CONCLUSIONS

Short walks in blue spaces can benefit both well-being and mood. However, we did not observe a positive effect of blue spaces for any of the cardiovascular outcomes assessed in this study.

Residential exposure to natural outdoor environments and general health among older adults in Shanghai, China

Background

Exposure to natural outdoor environments (NOE) has been shown to be beneficial to older adults’ health and functioning, yet this assertion has rarely been tested in China. We investigated the relationships between exposure to NOE and older adults’ self-rated health in Shanghai, China and examined whether these relationships varied by sex, age, education and hukou status.

Method

This cross-sectional study used micro-data sample of the 2010 Shanghai population census, including 7962 older adults nested within 3345 neighbourhoods. Self-rated health was the outcome variable. Four NOE exposure indicators were calculated for each neighbourhood: the amount of surrounding greenness/blueness and proximity to large green/blue spaces. Multilevel logistic regression was employed to explore the association between natural outdoor environment exposure and self-rated health, adjusting for individual-level and neighbourhood-level covariates. Stratified analyses were used to examine variations by sex, age, education and hukou status.

Results

Older adults living in neighbourhoods with higher surrounding greenness and higher proximity to both green spaces and blue spaces were more likely to report good health. Residential surrounding blueness was not significantly related to self-rated health. Females, those aged 60–69 years, those who had elementary school or junior high school education and those with non-local hukou benefit more from residential surrounding greenness, and those aged 70–79 years and who had elementary school or junior high school education benefit more from residential proximity to blue spaces.

Conclusions

Higher residential greenness and proximity to both green spaces and blue spaces were associated with better self-rated health, particularly for females, younger older adults, the low educated and non-local hukou holders. Our findings suggest that urban green spaces and urban blue spaces have different effects on health among Chinese older adults and that the assessment of exposure matters to the investigation of NOE-health relationships.

Long-term exposure to residential green and blue spaces and anxiety and depression in adults: A cross-sectional study

BACKGROUND

Although exposure to natural outdoor environments has been consistently associated with improved perceived general health, available evidence on a protective association between this exposure and specific mental health disorders such as depression and anxiety is still limited.

OBJECTIVE

The aim of this study was to evaluate the effects of long-term exposure to residential green and blue spaces on anxiety and depression and intake of related medication. Additionally, we aimed to explore potential mediators and effect modifiers of this association.

METHODS

The study was based on an existing adult cohort (ALFA - Alzheimer and Families) and includes 958 adult participants from Barcelona recruited in 2013-2014. For each participant residential green and blue exposure indicators [surrounding greenness (NDVI), amount of green (land-cover) and access to major green spaces and blue spaces] were generated for different buffers (100m, 300m and 500m). Participants reported their history of doctor-diagnosed anxiety and depressive disorders and intake of related medication. Logistic regression models were applied to assess the corresponding associations.

RESULTS

Increasing surrounding greenness was associated with reduced odds of self-reported history of benzodiazepines [e.g. Odds ratio - OR (95%CI) = 0.62 (0.43, 0.89) for 1-interquartile range (IQR) increase in NDVI in a 300m buffer] and access to major green spaces was associated with self-reported history of depression [OR (95%CI) = 0.18 (0.06, 0.58)]. No statistically significant associations were observed with blue spaces. Air pollution (between 0.8% and 29.6%) and noise (between 2.2% and 5.3%) mediated a proportion of the associations observed, whereas physical activity and social support played a minor role.

CONCLUSION

Our findings suggest a potential protective role of green spaces on mental health (depression and anxiety) in adults, but further studies, especially longitudinal studies, are needed to provide further evidence of these benefits and of the mediation role of exposures like air pollution and noise.

Residential green spaces and mortality: A systematic review

BACKGROUND

A number of studies have associated natural outdoor environments with reduced mortality but there is no systematic review synthesizing the evidence.

OBJECTIVES

We aimed to systematically review the available evidence on the association between long-term exposure to residential green and blue spaces and mortality in adults, and make recommendations for further research. As a secondary aim, we also conducted meta-analyses to explore the magnitude of and heterogeneity in the risk estimates.

METHODS

Following the PRISMA statement guidelines for reporting systematic reviews and meta-analysis, two independent reviewers searched studies using keywords related to natural outdoor environments and mortality.

DISCUSSION

Our review identified twelve eligible studies conducted in North America, Europe, and Oceania with study populations ranging from 1645 up to more than 43 million individuals. These studies are heterogeneous in design, study population, green space assessment and covariate data.We found that the majority of studies show a reduction of the risk of cardiovascular disease (CVD) mortality in areas with higher residential greenness. Evidence of a reduction of all-cause mortality is more limited, and no benefits of residential greenness on lung cancer mortality are observed. There were no studies on blue spaces.

CONCLUSIONS

This review supports the hypothesis that living in areas with higher amounts of green spaces reduces mortality, mainly CVD. Further studies such as cohort studies with more and better covariate data, improved green space assessment and accounting well for socioeconomic status are needed to provide further and more complete evidence, as well as studies evaluating the benefits of blue spaces.

Natural outdoor environments and mental and physical health: relationships and mechanisms

BACKGROUND

Evidence is growing for the beneficial impacts of natural outdoor environments on health. However, most of the evidence has focused on green spaces and little evidence is available on health benefits of blue spaces and about possible mediators and modifiers of such impacts. We investigated the association between natural outdoor environments (separately for green and blue spaces) and health (general and mental) and its possible mediators and modifiers.

METHODS

Cross-sectional data from adults interviewed in Catalonia (Spain) between 2010 and 2012 as part of the Catalonia Health Survey were used. The collected data included sociodemographic characteristics, self-perceived general health, mental health, physical activity and social support. Indicators of surrounding greenness and access to natural outdoor environments within 300 m of the residence and degree of urbanization were derived for residential addresses. Associations were estimated using logistic regression and negative binominal models.

RESULTS

Green spaces were associated with better self-perceived general health and better mental health, independent of degree of urbanization. The associations were more consistent for surrounding greenness than for access to green spaces. The results were consistent for different buffers, and when stratifying for socioeconomic status. Slightly stronger associations were found for women and residents of non-densely populated areas. No association was found between green spaces and social contacts and physical activity. The results for blue spaces were not conclusive.

CONCLUSION

Green spaces are associated with better general and mental health across strata of urbanization, socioeconomic status, and genders. Mechanisms other than physical activity or social support may explain these associations.