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.

Greenness-air pollution-physical activity-hypertension association among middle-aged and older adults: Evidence from urban and rural China.

BACKGROUND: Although some evidence suggests that residential greenness may prevent hypertension in urban areas, limited attention has been paid to urban-rural disparities in the association of greenness with hypertension in rapidly urbanizing developing countries. OBJECTIVES: The current study investigated the association between the amount of neighbourhood greenness and hypertension among middle and older aged people in Chinese urban and rural areas. It further examined whether PM2.5 (particulate matter ≤2.5 µm in aerodynamic diameter) concentrations, physical activity, and body mass index (BMI) mediated the association of greenness with hypertension. METHODS: We used data from 11 486 adults aged 50 years or above within the first wave of the Study on Global Ageing and Adult Health in China during 2007-2010. Hypertension was assessed by criterion-based measures of blood pressure. Residential greenness was characterized by satellite-derived Normalized Difference Vegetation Index. We employed multilevel generalized structural equation models to estimate the association between neighbourhood greenness and hypertension in urban and rural areas. Serial mediation models have been performed to test potential pathways linking greenness to hypertension. RESULTS: In rural areas, a greater amount of residential greenness was directly associated with a decrease in the odds of hypertension (odds ratio = 0.51, 95% confidence interval 0.29-0.89). No direct association was observed in urban areas (odds ratio = 1.33, 95% confidence interval 0.94-1.89). Serial mediation models showed that the association of greenness with hypertension was completely mediated by PM2.5 concentrations in urban areas, while the association of greenness with hypertension was only partially mediated by PM2.5 concentrations and serial PM2.5 concentrations-physical activity path in rural areas. There was no evidence that physical activity, air pollution-BMI path, air pollution-physical activity-BMI path, and physical activity-BMI path mediated the association in both urban and rural areas. CONCLUSIONS: Higher neighbourhood greenness was directly associated with a lower prevalence of hypertension among middle and older aged adults in rural China but not in urban areas. The association of greenness with hypertension was completely mediated by air pollution (without any mediation effect of physical activity and BMI) in urban areas. In contrast, the association was partly mediated by air pollution, physical activity, and other unobservables in rural areas. Further longitudinal studies are warranted to prove a cause-and-effect association, which may help policymakers and practitioners to conduce effective interventions to prevent and control the prevalence of hypertension and the attendant disease burden.

Establishing associations between residential greenness and markers of adiposity among middle-aged and older Chinese adults through multilevel structural equation models.

OBJECTIVES: Residential greenness may prevent overweight/obesity, but the matter has not been investigated among middle-aged and older adults in China. This study 1) assessed associations between residential greenness and markers of adiposity among middle-aged and older Chinese adults and 2) investigated physical activity, sedentary behaviours, particulate matter (PM) with a diameter of <2.5 µm (PM2.5) concentrations, and perennial mean temperature as mediators of the associations. METHODS: We used data from the World Health Organization's Study on Global Ageing and Adult Health (SAGE) between 2007 and 2010. Overweight/obesity and abdominal obesity were measured by body mass index and waist circumference. Exposure to neighbourhood greenness was measured by the normalized difference vegetation index (NDVI). Multilevel structural equation models were fitted to investigate the associations between neighbourhood greenness, the four potential mediators, and the prevalence of overweight/obesity and central obesity. RESULTS: The results showed that greenness was inversely associated with the odds of overweight/obesity (odds = 0.73, 95% confidence interval (CI) 0.58-0.92) and abdominal adiposity (odds = 0.55, 95% CI 0.33-0.91). The greenness-overweight/obesity association varied significantly by sex and age, and the greenness-central obesity varied significantly by sex, age, and education. We found some indication that PM2.5 concentrations had a suppressive effect on the greenness-adiposity associations. There was no evidence that physical activity, sedentary behaviours, and perennial mean temperature mediated the associations between neighbourhood greenness and markers of adiposity. CONCLUSIONS: Exposure to higher levels of residential greenness was associated with lower odds of overweight/obesity and abdominal obesity among middle-aged and older Chinese adults. However, underlying mechanisms explaining these associations remain unclear requiring longitudinal studies and natural experiments.

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.

Exploring the linkage between greenness exposure and depression among Chinese people: Mediating roles of physical activity, stress and social cohesion and moderating role of urbanicity.

Although a plethora of studies have investigated the association between green exposure and mental health in developed countries, it is only recently that academics and policymakers have paid attention to how this association works in rapidly urbanizing and developing countries. This study aims to explore biopsychosocial pathways linking residential greenness exposure to depression in the Chinese context using data from the 2016 wave of China Labour-force Dynamics Survey. Results from multilevel models along with mediation analysis show that exposure to residential greenness is negatively associated with depression, and that physical activity, stress and neighbourhood social cohesion altogether have a complete mediation effect on this association. Results from moderation analysis suggest that urbanicity moderates the relationship between greenness exposure and depression, and that the relationship is strongest at the upper level of urbanicity. Our findings suggest the necessity of increasing the provision of recreational green spaces and improving the quality of green spaces in Chinese less urbanized areas.

Exploring the association between urbanisation and self-rated health of older adults in China: evidence from a national population sample survey.

OBJECTIVES: This study investigated the association between urbanisation and self-rated health of older adults in China, particularly how different dimensions, rate and level of urbanisation are related to older people's health. Additionally, it examined the moderating effect of education on the association between each of the four dimensions of urbanisation and older people's health. DESIGN: The study uses a cross-sectional survey design. PARTICIPANTS: This study analysed 236 030 individuals (aged 60-79 years) nested within 267 prefecture-level cities from 2005 China's 1% population sample survey. OUTCOME MEASURES: Self-rated health was the outcome variable. Four groups of predictors assessed prefectures' level and rate of urbanisation: land-use conversion, economic growth, population concentration and health services. Multilevel logistic regression was used to examine the association between self-rated health and the level and rate of urbanisation, after adjusting for individual-level covariates. Multiplicative interactions explored variations by education. RESULTS: The odd of reporting fair or poor health was negatively associated with the level and rate of population concentration (OR 0.93,95%CI 0.87 to 0.99 and 0.74,95%CI 0.59 to 0.93, respectively) and positively associated with the level of health services (OR 1.12, 95% CI 1.06 to 1.19). Land-use conversion, economic growth and health service improvements (the forms of rate of urbanisation) were not significantly associated with self-rated health. Education had a moderating effect on the association between urbanisation and self-rated health. CONCLUSIONS: Older people living in more densely populated areas and areas undergoing rapid population concentration were less likely to report fair or poor health. This result supports healthy migration and 'salmon bias' hypotheses. No urban health penalty was observed for the older adults in China; therefore, the following pathways linking urbanisation to health are unclear: lifestyle changes, environmental pollution and cultivated land reduction.