Greenness surrounding schools and adiposity in children and adolescents: Findings from a national population-based study in China

Environmental impacts on childhood rhinitis: The role of green spaces, air pollutants, and indoor microbial communities in Taiyuan, a city in Northern China

Rhinitis is one of the most common respiratory diseases, influenced by various environmental factors such as green space, air pollution and indoor microbiomes. However, their interactions and combined effects have not been reported. We recruited 1121 preschool children from day care centers in a northern city of China. Health and demographic data were collected through questionnaires answered by the children's parents. Surrounding green space was assessed by Normalized Difference Vegetation Index (NDVI), Enhanced Vegetation Index (EVI) and land cover data of grassland proportion within 1500/3000 m. Ambient air pollution was estimated using the inverse distance weighted (IDW), and the indoor microbiome in classroom vacuum dust was profiled by bacterial 16S rRNA and fungal ITS amplicon sequencing. Mixed-effect logistic regression revealed the proportion of natural grassland, grassland leaf-off and total grassland was negatively associated with current rhinitis. Stratified analysis indicated that greater green space exposure was associated with a reduced current rhinitis in children at high levels of air pollution. Additionally, grassland also protects children against environmental tobacco smoke at home. Indoor microbiome analysis showed Haemophilus and Dolosigranulum were enriched in low-rhinitis day care centers, while Amaricoccus, Blautia and Mycosphaerella were enriched in high-rhinitis day care centers. Mediation analysis indicated that the indoor microbiome did not have significant mediating effects on the relationship between green space and children's current rhinitis. This is the first study to reveal interactions of green space, air pollution and indoor microbiome on rhinitis, providing new insights into how environmental factors collectively influence respiratory health in children.

Determinants of childhood obesity in China

Over the past four decades, China has witnessed an important nutritional transition, characterised by a heightened overnutrition burden among children. The country now has the largest population of children with obesity globally. In this paper, we review the epidemiology of childhood obesity in China, its determinants, and risk factors, with a particular focus on school-aged children. Evidence unveils substantial variations across age, gender, and region. We describe multilevel obesogenic determinants, including macro-level social, cultural, and environmental factors; meso-level factors related to schools and communities; and micro-level factors tied to families and individuals from the perinatal-infant stage to childhood and adolescence. The primary drivers of childhood obesity appear to be rooted in the broader macro-level social, economic, and technological environment; obesogenic factors, which have affected school, community, and family environments; and accelerated unhealthy behaviour uptake. Identifying and characterising the catalysts behind the rise in childhood obesity in China is imperative for the development of scalable, effective, and tailored prevention, control, and intervention strategies.

Association of the external environmental exposome and obesity: A comprehensive nationwide study in 2019 among Chinese children and adolescents

OBJECTIVE

Children and adolescents are particularly vulnerable to the effects of various environmental factors, which could disrupt growth processes and potentially lead to obesity. Currently, comprehensive and systematic assessments of these environmental exposures during developmental periods are lacking. Therefore, this study aims to evaluate the association between external environmental exposures and the incidence of obesity in children and adolescents.

METHODS

Data was collected from the 2019 Chinese National Survey on Students' Constitution and Health, including 214,659 Han children aged 7 to 19. Body Mass Index (BMI) and BMI-for-age z-score (zBMI) were the metrics used to assess overweight and obesity prevalence. The study assessed 18 environmental factors, including air pollutants, natural space, land cover, meteorological conditions, built environment, road conditions, and artificial light at night. Exposome-wide association study (ExWAS) to analyze individual exposures' associations with health outcomes, and Weighted Quantile Sum (WQS) to assess cumulative exposure effects.

RESULTS

Among the children and adolescents, there were 24.2 % participants classified as overweight or obesity. Notably, 17 out of 18 environmental factors exhibited significant associations with zBMI and overweight/obesity. Seven air pollutants, road conditions, and built density were positively correlated with higher zBMI and obesity risk, while NDVI, forests, and meteorological factors showed negative correlations. Co-exposure analysis highlighted that SO2, ALAN, PM10, and trunk road density significantly increased zBMI, whereas rainfall, grassland, and forest exposure reduced it. Theoretically reduction in the number and prevalence of cases was calculated, indicating potential reductions in prevalence of up to 4.51 % for positive exposures and 5.09 % for negative exposures. Notably, substantial reductions were observed in regions with high pollution levels.

CONCLUSION

This large-scale investigation, encompassing various environmental exposures in schools, highlights the significant impact of air pollution, road characteristics, rainfall, and forest coverage on childhood obesity.

Urban greenspaces and child blood pressure in China: Evidence from a large population-based cohort study

BACKGROUND

With the world's population steadily shifting toward urban living, children's engagement with the natural environment seems to be diminishing. This raises significant concerns about the influence of urban greenspaces on the cardiovascular health of children.

OBJECTIVE

To assess the association between urban greenspaces exposure and blood pressure (BP) in Chinese primary schoolchildren.

METHODS

This prospective cohort study used data from the Children's growth environment, lifestyle, physical, and mental health development (COHERENCE) project in Guangzhou, China. Participants included 164,853 primary schoolchildren starting from 2016/17 to 2019/20 academic year. We assessed the surrounding greenspaces at home and school by using Sentinel-2 satellite data on the normalized difference vegetation index. Prehypertension and hypertension status were defined with BP above 90th to less than the 95th percentile, at or above the 95th percentile, respectively. The association of surrounding greenness with children's BP levels and risk of prehypertension/hypertension were examined using linear mixed-effects models and Cox proportional hazards model.

RESULTS

Among 164,853 eligible children aged 7.21 (0.74) years, 89,190 (54.1%) were boys. Our results showed that average systolic and diastolic BP increased by 0.48 and 0.42 standard deviations, respectively, over the 3-year follow-up. We identified 23,225 new cases of prehypertension and 35,067 of hypertension status. An interquartile range increase both in home-, school- and home-school NDVI100m was significantly associated with a reduction of 0.018-0.037 in BP z-scores and a 2.7%-7.6% lower risk of hypertension. Additionally, family socioeconomic status modified the impact of home-school greenness on BP levels. Air pollution exhibited mediating effects solely in school-greenness-BP associations, while physical activity and children's BMI mainly mediated the relationships between home-greenness and BP.

CONCLUSION

The findings of this large cohort study suggest that surrounding greenspaces are associated with lower BP levels and a decreased risk of prehypertension and hypertension in Chinese schoolchildren.

Urban greenspace and visual acuity in schoolchildren: a large prospective cohort study in China

BACKGROUND

Greenspace is known to have a positive impact on human health and well-being, but its potential effects on visual acuity have not been extensively studied.

OBJECTIVES

Our aim was to examine the relationship between long-term greenspace exposure and visual acuity in children, while also exploring the potential mechanisms in this association.

METHODS

We conducted this prospective cohort study based on the Children's growth environment, lifestyle, physical, and mental health development project (COHERENCE), which screened 286,801 schoolchildren in Guangzhou, China, starting in the 2016/17 academic year and followed them up for three academic years (2017/18-2019/20). Visual acuity was measured using a standardized logarithmic chart, and visual impairment was defined as visual acuity worse than 0.0 logarithm of the minimum angle of resolution (LogMAR) units in the better eye. We used the Normalized Difference Vegetation Index (NDVI), the Soil-Adjusted Vegetation Index (SAVI), and the Enhanced Vegetation Index (EVI) to assess the greenspace surrounding child's geocoded home and school at each visit.

RESULTS

Our analysis indicated that higher greenspace exposure was associated with greater visual acuity z-score at baseline and with slower decline in visual acuity z-score during the 3-year follow-up. An interquartile range increase in home-school-based NDVI 300m was associated with a 7% decrease [hazard ratios (HRs): 0.93, 95% confidence interval (CI): 0.92, 0.94] in the risk of visual impairment. We also found that air pollution, physical activity, outdoor time, and recreational screen time partially mediated the greenspace-visual acuity association.

CONCLUSION

Our findings suggest that increasing greenspace exposure could benefit children's visual acuity development and reduce the risk of visual impairment by reducing air pollution and recreational screen time while increasing physical activity and outdoor time. All results could have potential policy implications, given the individual and societal burdens associated with visual impairment.

Association of greenness surrounding school with aggression among adolescents: A multi-site study in China

Association of greenness surrounding school with aggression among adolescents was not well understood. This study aimed to investigate the associations of greenness surrounding school with adolescents' total and sub-types of aggression and explore potential mediators underlying these associations. A multi-site study of 15,301 adolescents aged 11-20 years were recruited through a multistage, random cluster sampling across 5 representative provinces in mainland China. Satellite-derived Normalized Difference Vegetation Index (NDVI) values within circular buffers of 100 m, 500 m, and 1000 m surrounding school were used to indicate the adolescents' greenness exposure. We used the Chinese version of Buss and Warren's Aggression Questionnaire to assess total and sub-types of aggression. Daily concentrations of PM2.5, and NO2 were obtained from the China High Air Pollutants datasets. Per IQR increment of NDVI 100 m and 500 m surrounding school was associated with lower odds of total aggression; odds ratio [OR] with 95% CI was 0.958 (0.926-0.990) for the 100 m buffer and 0.963 (0.932-0.996) for the 500 m buffer, respectively. Similar associations can be observed in two sub-types of aggression, including verbal (NDVI 100 m: 0.960 (0.925-0.995); NDVI500m: 0.964 (0.930-0.999)) and indirect aggression (NDVI 100 m: 0.956 (0.924-0.990); NDVI500m: 0.953 (0.921-0.986)). There were no sex and age differences in the associations of school surrounding greenness with aggression, except that the beneficial associations of greenness exposure with total aggression (0.933(0.895-0.975) vs.1.005(0.956-1.056)), physical aggression (0.971(0.925-1.019) vs.1.098(1.043-1.156)), and hostility (0.942(0.901-0.986) vs.1.016(0.965-1.069)) were greater among participants aged ≥16 years than those aged<16 years. PM2.5 (proportion mediated estimates: 0.21; 95% CI: 0.08, 0.94) and NO2 (-0.78, 95% CI: -3.22, -0.37) mediated the association of NDVI 500 m surrounding school with total aggression. Our data indicated that exposure to greenness in school surroundings was associated with reduced aggression, particularly in verbal and indirect aggression. The presence of PM2.5 and NO2 partially mediated these associations.

Exposure to ambient air pollution with depressive symptoms and anxiety symptoms among adolescents: A national population-based study in China

BACKGROUND

Air pollution threatens adolescents' physical health and adversely affects adolescents' mental health. Previous studies mostly focused on the effects of air pollution on physical health, but there were few studies on the effects of air pollution on mental health.

METHODS

We collected scores of depressive symptoms and anxiety symptoms from 15,331 adolescents from 43 schools in eleven provinces in September and November 2017. The data on air pollution comes from the China High Air Pollutants dataset, which included concentrations of particulate matter with diameters of ≤1.0 μm (PM₁), diameters of ≤2.5 μm (PM_2.5), and diameters of ≤10 μm (PM₁₀), as well as nitrogen dioxide (NO₂). The associations between air pollution and depressive and anxiety symptoms among adolescents were estimated using generalized linear mixed models.

RESULTS

Depressive and anxiety symptoms among Chinese adolescents were 16% and 32%, respectively. In the adjusted model, an interquartile range (IQR) increase from PM_2.5 was associated with the odds of anxiety symptoms [odds ratio (OR) = 1.01; 95% confidence interval (CI): 1.00, 1.01, P = 0.002]. Also, an IQR increase in PM₁₀ was significantly associated with the odds of anxiety symptoms (OR = 1.01; 95% CI: 1.00, 1.01, P = 0.029). Compared with the lowest quartile, the adjusted OR of anxiety symptoms for the highest quartile of PM_2.5 and PM₁₀ were 1.29 (1.15, 1.44) and 1.23 (1.06, 1.42), respectively. In addition, the association between PM_2.5 and depressive symptoms was significant. The robustness of the results was also confirmed by stratification and sensitivity analyses.

CONCLUSIONS

Exposure values for airborne particulate matter were associated with depressive symptoms and anxiety symptoms in adolescents, particularly for PM_2.5 and PM₁₀ with anxiety symptoms among adolescents.

Residential greenness and air pollution concerning excessive gestational weight gain during pregnancy: A cross-sectional study in Wuhan, China

BACKGROUND

Previous studies have indicated that exposure to residential greenness may benefit the health status of pregnant women, and air pollution may exert a mediating effect. Gestational weight gain (GWG) is an important indicator of pregnant women and fetuses' health and nutrition status. However, evidence concerning the impact of residential greenness on excessive gestational weight gain (EGWG) is scarce, and to what extent air pollution in urban settings mediates this relationship remains unclear.

OBJECTIVE

This study aims to explore the association of residential greenness with EGWG, consider the mediating effect of air pollution, and estimate the combined impact of residential greenness and air pollution exposures on EGWG.

METHOD

This population-based cross-sectional study involved 51,507 pregnant women with individual-level data on residential addresses in the Wuhan Maternal and Child Health Management Information System. Two spectral indexes, the normalized difference vegetation index (NDVI) and soil-adjusted vegetation index (SAVI), were used to proxy residential greenness. The air pollution data included six indicators (PM_2.5, PM₁₀, SO₂, CO, NO₂, O₃) and used the Ordinary Kriging interpolation method to estimate overall pregnancy exposure to air pollutants. Generalized linear mixed regression models were utilized to explore the relationship between residential greenness and EGWG. Restricted cubic spline (RCS) models were developed to examine the dose-response relationships. Mediation analyses explored the potential mediating role of air pollution in the residential greenness-EGWG associations. Finally, the weighted-quantile-sum (WQS) regression model was used to investigate the association between residential greenness-air pollutants co-exposure and EGWG.

RESULT

Among all participants, 26,442 had EGWG. In the adjusted model, the negative association was found significant for NDVI_100-m, NDVI_200-m, and NDVI_500-m with EGWG. For example, each IQR increase in NDVI_100-m was associated with 2.8% (95% CI: 0.6-5.0) lower odds for EGWG. The result of WQS regression showed that, when considering the six air pollutants and NDVI_-100m together, both positive and negative WQS indices were significantly associated with EGWG, PM₁₀, PM_2.5, with SO₂ having significant weights in the positive effect direction and CO, O₃, NO₂, and NDVI_100-m having a negative effect. Our results also suggested that SO₂, NO₂, PM₁₀, PM_2.5, and CO significantly mediated the association between NDVI_-100m and EGWG, and our estimates were generally robust in the sensitivity analysis.

CONCLUSION

Exposure to a higher level of residential greenness is associated with a reduced risk of EGWG, in which air pollution may exert a mediating effect. Pregnant women might benefit more in gaining healthy gestational weight when greenness levels increase from low to medium than from medium to high. Given the current cross-sectional study design, large-sale prospective cohort studies are needed to confirm our findings further.

The role of residential greenness levels, green land cover types and diversity in overweight/obesity among older adults: A cohort study

BACKGROUND

Few studies have investigated the effects of greenness exposure, green land cover types and diversity and their interaction with particulate matter (PM) to adiposity.

METHOD

Cohort data were collected from the Chinese Longitudinal Healthy Longevity Survey (CLHLS). Baseline data on greenness levels, green land cover types and diversity were assessed by the Normalized Difference Vegetation Index (NDVI), three greenery types (trees, shrublands and grassland) and Shannon's diversity index, respectively. Body mass index (BMI) and waist circumference (WC) were separately used as dependent variables and represented for peripheral overweight/obesity and central obesity, respectively. The mixed Cox model with random intercept was used to estimate the effects of greenness levels, types and diversity on overweight/obesity using single and multiple exposure models. We also examined the interaction of PM and the aforementioned indicators on overweight/obesity on both additive and multiplicative scales.

RESULTS

Single exposure models showed that higher levels of residential greenness, tree coverage and ratio of trees to shrublands/grassland were inversely associated with peripheral overweight/obesity and central obesity. An increase in shrublands, grassland and diversity of green was related to lower odds of peripheral overweight/obesity. Multiple exposure models confirmed the association between greenness levels and peripheral overweight/obesity. Males, educated participants and elderly who lived in southern regions and areas with cleaner air environments acquired more benefits from greenspace exposure. Single and multiple exposure models indicated that an antagonistic effect of increasing PM and decreasing greenness levels on peripheral overweight/obesity and central obesity. Single exposure models showed the potential interaction of tree coverage, ratio of trees to grassland and PM_2.5 exposures on the risk of peripheral overweight/obesity.

CONCLUSION

Increasing residential greenness and diversity of green were associated with healthy weight status. The relationship between greenery and overweight/obesity varied, and the effects of greenspace exposure on overweight/obesity were associated with air pollution.

Associations between greenspace surrounding schools and lipid levels in Chinese children and teenagers

Little evidence exists concerning the associations of greenspace with childhood lipid profiles and dyslipidemias, especially in developing countries and regions. We aimed to investigate the associations of greenspace surrounding schools with lipid levels and dyslipidemia prevalence among Chinese children and teenagers. We obtained baseline information and health data of 10,408 children and teenagers (aged 6-18 years) who studied from 94 schools in China. We measured levels of four blood lipids: triglycerides (TG), total cholesterol (TC), high-density lipoprotein cholesterol (HDL-C) and low-density lipoprotein cholesterol (LDL-C). Dyslipidemias were defined using standard recommendations. Greenness surrounding schools were assessed using two satellite-based greenness indices, Normalized Difference Vegetation Index (NDVI) and Soil Adjusted Vegetation Index (SAVI) at 300-, 500-, and 1000-m circular buffers based on each school's latitude and longitude. We used random forest model combined with meteorological and remote sensing data to estimate air pollution levels surrounding each school. We used generalized linear mixed models to estimate the associations of greenness with lipid levels and dyslipidemias prevalence. We also performed sub-group and mediation analyses. An interquartile range (IQR) increase in NDVI_500m was significantly associated with a 0.064 mmol/L (95% confidence interval [CI]: 0.083, -0.045) and 0.049 mmol/L (95% CI: 0.065, -0.033) decreased TC and LDL-C levels, respectively, as well as a 0.13-fold (95% CI: 0.01, 0.23) and 0.17-fold (95% CI: 0.01, 0.30) decreased odds of hypercholesterolemia and hyperbetalipoproteinemia, respectively. Associations were stronger in students aged ≤12 years and born to parents having lower education levels compared to their counterparts. Particle with aerodynamic diameter ≤2.5 μm (PM_2.5) mediated 61.5% and 16.7% of the association of greenness with TG and LDL-C levels, respectively. In summary, higher school-based greenness exposure was beneficially associated with lipid levels among Chinese children and adolescents, and part of the association can be explained by lowed PM_2.5 levels.

Air pollution, greenness and risk of overweight among middle-aged and older adults: A cohort study in China

BACKGROUND

Exposure to air pollution may increase the risk of obesity, but living in greener space may reduce this risk. Epidemiological evidence, however, is inconsistent.

METHODS

Using data from the China Health and Retirement Longitudinal Study (2011-2015), we conducted a nationwide cohort study of 7424 adults. We measured overweight/obesity according to body mass index. We used annual average ground-level air pollutants, including ozone (O3), nitrogen dioxide (NO2), and particulate matter with aerodynamic diameters ≤2.5 μm (PM2.5), to demonstrate air pollution levels. We used the Normalized difference vegetation index (NDVI) to measure greenness exposure. We used time-varying Cox proportional hazard regression models to analyze the connections among air pollution, greenness, and the development of overweight/obesity in middle-aged and older adults in China. We also conducted mediation analyses to examine the mediating effects of air pollution.

RESULTS

We found that lower risk of overweight/obesity was associated with more greenness exposure and lower levels of air pollution. We identified that an interquartile increment in NDVI was correlated with a lower hazard ratio (HR) of becoming overweight or obese (HR = 0.806, 95% confidence interval [CI]: 0.754-0.862). Although a 10 μg/m3 increase in PM2.5 and NO2 was correlated with higher risks (HR = 1.049, 95% CI = 1.022-1.075, HR = 1.376, 95% CI = 1.264-1.499). Effects of PM2.5 on being overweight or obese were stronger in men than in women. According to the mediation analysis, PM2.5 and NO2 mediated 8.85% and 19.22% of the association between greenness and being overweight or obese.

CONCLUSIONS

An increased risk of being overweight or obese in middle-aged and older adults in China was associated with long-term exposure to higher levels of PM2.5 and NO2. This risk was reduced through NDVI exposure, and the associations were partially mediated by air pollutants. To verify these findings, fine-scale studies are needed.

Associations of ambient temperature with mortality for ischemic and hemorrhagic stroke and the modification effects of greenness in Shandong Province, China

BACKGROUND

Evidence is scant on the relative and attributable contributions of ambient temperature on stroke subtypes mortality. Few studies have examined modification effects of multiple greenness indicators on such contributions, especially in China. We quantified the associations between ambient temperature and overall, ischemic, and hemorrhagic stroke mortality; further examined whether the associations were modified by greenness.

METHODS

We conducted a multicenter time-series analysis from January 1, 2013 to December 31, 2019. we adopted a distributed lag non-linear model to evaluate county-specific temperature-stroke mortality associations. We then applied a random-effects meta-analysis to pool county-specific effects. Attributable mortality was calculated for cold and heat, defined as temperatures below and above the minimum mortality temperature (MMT). Finally, We conducted a multivariate meta-regression to determine associations between greenness and stroke mortality risks for cold and heat, using normalized difference vegetation index (NDVI), soil adjusted vegetation index (SAVI), and enhanced vegetation index (EVI) as quantitative indicators of greenness exposure.

RESULTS

In the study period, 138,749 deaths from total stroke were reported: 86,873 ischemic and 51,876 hemorrhagic stroke. We observed significant W-shaped relationships between temperature and stroke mortality, with substantial differences among counties and regions. With MMT as the temperature threshold, 17.16 % (95 % empirical CI, 13.38 %-19.75 %) of overall, 20.05 % (95 % eCI, 16.46 %-22.70 %) of ischemic, and 12.55 % (95 % eCI, 5.59 %-16.24 %) of hemorrhagic stroke mortality were attributable to non-optimum temperature (combining cold and heat), more mortality was caused by cold (14.94 %; 95 % eCI, 11.57 %-17.34 %) than by heat (2.22 %; 95 % eCI, 1.54 %-2.72 %). Higher levels of NDVI, SAVI and EVI were related to mitigated effects of non-optimum temperatures-especially heat.

CONCLUSIONS

Exposure to non-optimum temperatures aggravated stroke mortality risks; increasing greenness could alleviate that risks. This evidence has important implications for local communities in developing adaptive strategies to minimize the health consequences of adverse temperatures.

Greenspace and health outcomes in children and adolescents: A systematic review

An increasing body of evidence has linked greenspace and various health outcomes in children and adolescents, but the conclusions were inconsistent. For this review, we comprehensively summarized the measurement methods of greenspace, resultant health outcomes, and potential mechanisms from epidemiological studies in children and adolescents (aged ≤19 years). We searched for studies published and indexed in MEDLINE and EMBASE (via Ovid) up to April 11, 2022. There were a total of 9,291 studies identified with 140 articles from 28 countries finally assessed and included in this systematic review. Over 70% of the studies were conducted in highly urbanised countries/regions, but very limited research has been done in low-and middle-income countries and none in Africa. Measures of greenspace varied. Various health outcomes were reported, including protective effects of greenspace exposure on aspects of obesity/overweight, myopia, lung health, circulatory health, cognitive function, and general health in children and adolescents. The associations between greenspace exposure and other health outcomes were inconsistent, especially for respiratory health studies. We pooled odds ratios (OR) using random-effects meta-analysis for health outcomes of asthma (OR = 0.94, 95%CI: 0.84 to 1.06), allergic rhinitis (OR = 0.95; 95% CI: 0.73 to 1.25), and obesity/overweight (OR = 0.91, 95%CI: 0.84 to 0.98) with per 0.1 unit increase in normalized difference in vegetation index (NDVI). These associations have important implications for the assessment and management of urban environment and health in children and adolescents.

Associations of greenness surrounding schools and self-reported depressive and anxiety symptoms in Chinese adolescents

BACKGROUND

The effect of school-based greenness exposure on mental health among adolescents remains unclear. The study aimed to estimate the associations between school-based greenness and depressive and anxiety symptoms among adolescents and explore potential modifier and mediator between the associations.

METHODS

A cross-sectional survey involving 15,559 adolescents was conducted in China. The Chinese version of the Center for Epidemiologic Studies Depression 9-Item Scale and the Generalized Anxiety Disorder 7-Item Scale were used to assess the depressive and anxiety symptoms among adolescents. The Normalized Difference Vegetation Index within a 400 m and 800 m zone surrounding schools was used to indicate the adolescents' exposure to greenness. We estimated daily concentrations of PM_1.0, PM_2.5, and NO₂ from the China High Air Pollutants dataset. Multiple logistic regression models were used.

RESULTS

Higher exposure to greenness surrounding schools was negatively associated with depressive (OR: 0.774, 95%CI: 0.685-0.875) and anxiety symptoms (0.740, 0.669-0.818). We observed stronger associations between greenness and depressive and anxiety symptoms among girls, lower age group (11-15 years), and adolescents born to parents with lower education levels. PM_1.0 (proportion mediated estimates: 14.3 %; 95 % CI: 4.2 %, 24.5 %) and PM_2.5 (10.5 %; 95 % CI: 3.0 %, 17.9 %) mediated the associations between greenness exposure and depressive symptoms. The number of days adolescents attended physical education classes per week mediated -22.8 % (95 % CI: -38.5 %, -7.1 %) and -9.7 % (95 % CI: -15.5 %, -3.8 %) of the effects of greenness on depressive and anxiety symptoms.

CONCLUSIONS

Increasing the greenness and improving the environment surrounding schools is effective in promoting the mental health of adolescents.

Association of decreases in PM2.5 levels due to the implementation of environmental protection policies with the incidence of obesity in adolescents: A prospective cohort study

AIMS

To explore the association between decreased levels of particulate matter (≤2.5 µm; PM2.5) due to the implementation of environmental protection policies and the incidence of obesity in adolescents in Chongqing, China through a prospective cohort study.

METHODS

A total of 2105 children (52.02% male; aged 7.33 ± 0.60 years at baseline) were enrolled from the Chongqing Children's Health Cohort. A mixed linear regression model was used to analyse the relationships of PM2.5 levels with obesity indicators after adjusting for covariates. Additionally, a Poisson regression model was used to determine the relationship between PM2.5 exposure and the incidence of overweight/obesity.

RESULTS

The average PM2.5 exposure levels from participant conception to 2014, from 2015 to 2017, and from 2018 to 2019 were 66.64 ± 5.33 μg/m3, 55.49 ± 3.78 μg/m3, and 42.50 ± 1.87 μg/m3, respectively; these levels significantly decreased over time (P < 0.001). Throughout the entire follow-up period, the incidence of overweight/obesity after a ≥ 25 μg/m3 decrease in the PM2.5 level was 4.57% among females; this incidence was the lowest among females who experienced remarkable decreases in PM2.5 exposure. A 1-µg/m3 decrease in the PM2.5 level significantly decreased the body mass index (BMI), BMI z score (BMIz), and weight of adolescents (all P < 0.001). Compared with a < 20-μg/m3 decrease in the PM2.5 level, a ≥ 25-μg/m3 decrease protected against increased BMI (net difference= -0.93; 95% confidence interval [CI]: (-1.23,-0.63) kg/m2), BMIz (-0.28 (-0.39, -0.17)), weight (-1.59 (-2.44, -0.74) kg), and incidence of overweight/obesity (0.48 (0.37, 0.62), P < 0.001). Moreover, compared with a < 20-μg/m3 decrease in the PM2.5 level, a ≥ 25-μg/m3 decrease resulted in significant absolute differences in BMI (-1.26 (-1.56, -0.96) kg/m2), BMIz (-0.53 (-0.65, -0.40)) and weight (-3.01 (-3.8, -2.19) kg) (all P < 0.001).

CONCLUSIONS

This study showed the etiological relevance of declining PM2.5 concentrations for the incidence of obesity in children and adolescents, suggesting that controlling ambient air pollutants may prevent the development of obesity in this age group. Continuous implementation of environmental protection policies in China has led to substantial health benefits.

Associations of residential greenness with obesity and BMI level among Chinese rural population: findings from the Henan Rural Cohort Study

In recent years, increasing evidence supports the notion that obesity risk is affected by residential greenness. However, limited studies have been established in low- and middle-income countries, especially in China. The study aimed to evaluate the associations of residential greenness with obesity and body mass index (BMI) level in Chinese rural-dwelling adults. A total of 39,259 adults from the Henan Rural Cohort Study (HRCS) were included in the analyses. According to the guideline for prevention and control of overweight and obesity in Chinese adults, obesity was defined as BMI ≥ 28 kg/m². Residential greenness was measured by satellite-based normalized difference vegetation index (NDVI) and enhanced vegetation index (EVI). Generalized linear mixed models were used to study the associations between exposure to residential greenness with obesity and BMI level. Higher residential greenness was significantly correlated with lower odds of obesity and BMI level. For example, in the full-adjusted analyses, an interquartile range (IQR) increase in EVI_500-m was linked with reduced odds of obesity (OR = 0.77, 95%CI 0.72-0.82) and BMI level (β =  - 0.41 kg/m², 95%CI - 0.48 to - 0.33 kg/m²). Mediation analyses showed air pollution and physical activity could be potential mediators in these associations. Besides, we found that the association of NDVI_500-m with BMI was stronger in females and low-income populations. Higher residential greenness was associated with a lower prevalence of obesity and BMI level, particularly among females and the low-income population. These relationships were partially mediated by reducing air pollution and increasing physical activity.

Could greenness modify the effects of physical activity and air pollutants on overweight and obesity among children and adolescents?

Greenness could theoretically increase the impact of physical activity (PA) and reduce the adverse effects of air pollution on overweight/obesity. However, no evidence systematically compares these two pathways, especially in longitudinal studies of children and adolescent's cohort. Greenness, PA, and air pollution were assessed by Normalized Difference Vegetation Index (NDVI), International Physical Activity Short Form, and 7 pollutants (PM₁, PM_2.5, PM₁₀, SO₂, NO₂, CO, and O₃). Each exposure was divided into low-/high-level groups based on the 50% quantile. Proportional hazards and logistic regression model were used to assess the associations of greenness, PA, pollutants with overweight/obesity. The incidence of overweight/obesity was 1.98% in the national survey, and the cumulative incidence and incidence density were 12.76% and 3.43 per 100 person-year in the dynamic cohort, separately. An increase of 0.1 units in NDVI was associated with a 12% lower risk of overweight/obesity, but no significant link between PA and incidence was observed. The HRs of the high-level of PM₁, PM_2.5, PM₁₀, SO₂, NO₂, CO, and O₃ on the risk of overweight/obesity were 2.21, 2.63, 1.88, 2.38, 1.33, 2.43, and 1.33 in the low-level of greenness, which was higher than those in the high-level of greenness. The AFs of PM₁, PM_2.5, PM₁₀, SO₂, NO₂, CO, and O₃ were 25.58%, 44.37%, 22.96%, 29.15%, 11.55%, 29.50%, and 10.92% in the low-level of greenness, which simultaneously was higher than those in the high-level of greenness. Moreover, the risk of overweight/obesity associated with high-level of greenness in the high-level of PM₁₀, SO₂, CO were 0.83, 0.81, and 0.83 respectively. Our findings confirmed that greenness has a moderating effect on the effects of air pollutants on childhood overweight/obesity especially in heavy-industry areas where PM₁₀, SO₂, and CO are the major pollutants, although it did not influence the association between PA and overweight/obesity risks.

Living near greenness is associated with higher bone strength: A large cross-sectional epidemiological study in China

BACKGROUND

Living near green spaces may benefit various health outcomes. However, no studies have investigated the greenness-bone linkage in the general population. Moreover, to which extent ambient air pollution (AAP), physical activity (PA), and body mass index (BMI) mediate this relationship remains unclear. We aimed to explore the association between greenness and bone strength and the potential mediating roles of AAP, PA, and BMI in Chinese adults.

METHODS

This cross-sectional analysis enrolled 66,053 adults from the China Multi-Ethnic Cohort in 2018-2019. The normalized difference vegetation index (NDVI) and enhanced vegetation index (EVI) were employed to define residential greenness. The calcaneus quantitative ultrasound index (QUI) was used to indicate bone strength. Multiple linear regression models and mediation analyses were used to estimate the residential greenness-bone strength association and potential pathways operating through AAP (represented by PM_2.5 [particulate matter <2.5 μm in diameter]), PA, and BMI. Stratification analyses were performed to identify susceptible populations.

RESULTS

Higher residential exposure to greenness was significantly associated with an increase in QUI, with changes (95% confidence interval) of 3.28 (3.05, 3.50), 3.57 (3.34, 3.80), 2.68 (2.46, 2.90), and 2.93 (2.71, 3.15) for every interquartile range increase in NDVI_500m, NDVI_1000m, EVI_500m, and EVI_1000m, respectively. Sex, urbanicity, annual family income, smoking, and drinking significantly modified the association of greenness-bone strength, with more remarkable associations in males, urban residents, subjects from wealthier families, smokers, and drinkers. For the NDVI_500m/EVI_500m-QUI relationship, the positive mediating roles of PM_2.5 and PA were 6.70%/8.50 and 2.43%/2.69%, respectively, whereas those negative for BMI and PA-BMI were 0.88%/1.06% and 0.05%/0.05%, respectively.

CONCLUSION

Living in a greener area may predict higher bone strength, particularly among males, urban residents, wealthier people, smokers, and drinkers. AAP, PA, BMI, and other factors may partially mediate the positive association. Our findings underscore the importance of optimizing greenness planning and management policies.

Association between built environments and weight status: evidence from longitudinal data of 9589 Australian children

Background

No studies appear to examine potential associations between changes in built environments across childhood and the developmental trajectories of child weight status.

Objective

Examine the developmental trajectories of child weight status with respect to changes in childhood exposure to the built environments.

Methods

This study used data of 9589 children with biennial follow-up (2004–2016), retrieved from the Longitudinal Study of Australian Children. Changes in objectively-measured child weight status (i.e., body mass index-BMI, waist circumference) were investigated in relation to changes in seven built environments (i.e., neighbourhood safety; green space quality; footpaths and street conditions; public transport; shopping facilities; basic services; and local traffic) subjectively reported by caregivers. Group-based discrete trajectory mixture models were used to classify children according to their developmental trajectories of built environments and weight status. Multilevel multinomial logistic regression was employed to examine associations between built environments and child weight status adjusted for confounding.

Results

Two, four, and six trajectory groups were developed for built environment variables. Three groups namely “moderate”, “high”, and “extreme increase” were generated for each BMI and waist circumference. Findings from multilevel analyses indicated that growing up in neighbourhoods that are considered highly safe, with better quality of green space nearby, and in areas with low local traffic over time are protective against unhealthy weight increase in childhood. Meanwhile, living with better access to shopping facilities and basic services was associated with an unhealthy increase in BMI and/or waist circumference. No clear associations appeared between the quality of footpath and street conditions, access to public transport, and child weight status.

Conclusions

Built environments might act either as a risk or protective factor of an unhealthy increase in child weight status. Enabling health-promoting neighbourhoods (i.e., highly safe, quality green space nearby, low local traffic) is important to support a healthy weight trajectory across childhood.

The Association between Greenness and Urbanization Level with Weight Status among Adolescents: New Evidence from the HBSC 2018 Italian Survey

Recent studies have examined how the environment can influence obesity in young people. The research findings are conflicting: in some studies, green spaces have shown a protective association with obesity and urbanization has turned out to worsen this condition, while other studies contradicted these results. The aim of the study was to examine the relationships between greenness, urbanization, and weight status among Italian adolescents. Student data (11-13 years old) on weight and height, physical activity (PA), and demographic characteristics were extracted from the 2018 Health Behaviour in School-aged Children (HBSC) survey in Piedmont, Northwest of Italy. Data on Normalized Difference Vegetation Index (NDVI) and urbanization were obtained from satellite images and the National Institute of Statistics (ISTAT). A multilevel regression model was used to assess the association between NDVI, urbanization, and obesity, controlling for PA. Students living in greener areas reported a lower likelihood of being obese [OR = 0.11, 95% CI 0.02-0.56, p = 0.007], while students living in areas with a higher level of urbanization showed a significantly increased risk of obesity [OR = 2.3, 95% CI:1.14-4.6, p = 0.02]. Living surrounded by higher amounts of greenness and lower levels of urbanization may positively influence health status through lower risk of obesity among youth.

Association between greenspace and blood pressure: A systematic review and meta-analysis

Many studies have investigated the association between greenspaces and blood pressure (BP), but the results remain mixed. We conducted a systematic review and meta-analysis to comprehensively evaluate the evidence concerning greenspaces with BP levels and prevalent hypertension. Systematic literature searches were performed in Web of Science, PubMed, and Embase up to 25 April 2021. Combined effect estimates were calculated using random-effect models for each greenspace exposure assessment method that had been examined in ≥3 studies. Sensitivity analysis, subgroup analysis, and publication bias were also conducted. Of 38 articles (including 52 analyses, 5.2 million participants in total) examining the effects of normalized difference vegetation index (NDVI) (n = 23), proportion of greenspace (n = 11), distance to greenspace (n = 9), and others (n = 9) were identified. Most studies (65%) reported beneficial associations between greenspaces and BP levels/hypertension. Our results of meta-analyses showed that higher NDVI_500m was significantly associated with lower levels of systolic blood pressure (SBP = -0.77 mmHg, 95%CI: -1.23 to -0.32) and diastolic blood pressure (DBP = -0.32 mmHg, 95%CI: -0.57 to -0.07). We also found that NDVI in different buffers and the proportion of greenspaces were significantly associated with lower odds (1-9%) of hypertension. However, no significant effect was found for distance to greenspaces. In summary, our results indicate the beneficial effects of greenspace exposure on BP and hypertension. However, future better-designed studies, preferably longitudinal, are needed to confirm and better quantify the observed benefits in BP and/or hypertension.

Status of Cardiovascular Health in Chinese Children and Adolescents

Background

The American Heart Association defined “ideal cardiovascular health (CVH)” in pediatric populations to promote primordial prevention in cardiovascular diseases. Little is known about CVH and associated sociodemographic factors among Chinese children and adolescents.

Objectives

This study aimed to evaluate CVH and the associations with sociodemographic characteristics in Chinese children and adolescents.

Methods

This cross-sectional study analyzed baseline data of 15,583 participants aged 7 to 17 years from a Chinese national intervention program against obesity (2013-2014). CVH status was estimated according to 4 health behaviors (nonsmoking, body mass index, physical activity, and diet) and 3 health factors (total cholesterol, blood pressure, and fasting plasma glucose), using revised American Heart Association criteria. Multinomial logistic regression was used to assess the association between sociodemographic characteristics and the number of ideal CVH metrics.

Results

The prevalence of ideal CVH status was 1.7% (males: 1.9%; females: 1.6%) in the study population. The prevalence of ideal CVH behaviors and ideal health factors was 3.1% (males 3.3%; females: 3.0%) and 53.6% (males: 52.4%; females: 54.9%), respectively. Ideal fasting plasma glucose was the most prevalent component (males: 94.4%; females: 97.4%), whereas ideal physical activity (males: 34.6%; females: 23.9%) and diet (males: 28.3%; females: 30.1%) were the least prevalent. Female sex, younger age, undeveloped economy, residence in the southern region, and no family history of cardiovascular diseases were associated with more ideal CVH metrics.

Conclusions

Ideal CVH status in Chinese children and adolescents is alarmingly rare. Physical activity and diet are key to promotion of CVH. Effective interventions are needed to promote CVH and reduce health disparities in early life.

Green CURIOCITY: a study protocol for a European birth cohort study analysing childhood heat-related health impacts and protective effects of urban natural environments

INTRODUCTION

The European climate is getting warmer and the impact on childhood health and development is insufficiently understood. Equally, how heat-related health risks can be reduced through nature-based solutions, such as exposure to urban natural environments, is unknown. Green CURe In Outdoor CITY spaces (Green CURIOCITY) will analyse how heat exposure during pregnancy affects birth outcomes and how long-term heat exposure may influence children's neurodevelopment. We will also investigate if adverse effects can be mitigated by urban natural environments. A final goal is to visualise intraurban patterns of heat vulnerability and assist planning towards healthier cities.

METHODS AND ANALYSIS

We will use existing data from the Human Early-Life Exposure cohort, which includes information on birth outcomes and neurodevelopment from six European birth cohorts. The cohort is linked to data on prenatal heat exposure and impact on birth outcomes will be analysed with logistic regression models, adjusting for air pollution and noise and sociobehavioural covariates. Similarly, impact of cumulative and immediate heat exposure on neurodevelopmental outcomes at age 5 will be assessed. For both analyses, the potentially moderating impact of natural environments will be quantified. For visualisation, Geographical information systems data will be combined to develop vulnerability maps, demonstrating urban 'hot spots' where the risk of negative impacts of heat is aggravated due to sociodemographic and land use patterns. Finally, geospatial and meteorological data will be used for informing GreenUr, an existing software prototype developed by the WHO Regional Office for Europe to quantify health impacts and augment policy tools for urban green space planning.

ETHICS AND DISSEMINATION

The protocol was approved by the Comité Ético de Investigación Clínica Parc de Salut MAR, Spain. Findings will be published in peer-reviewed journals and presented at policy events. Through stakeholder engagement, the results will also reach user groups and practitioners.

Is residential greenness associated with dyslipidemia and lipid levels in Chinese rural-dwelling adults? The Henan rural cohort study

Scarce epidemiologic research examined the associations between residential greenness and dyslipidemia or lipid levels in low/middle-income countries. Baseline statistics (2015-2017) of 39,259 rural-dwelling adults were obtained from a Chinese longitudinal study. The blood lipid level was measured utilizing an enzymatic assay method. According to the 2016 Chinese guidelines on dyslipidemia (revision), patients with dyslipidemia were defined. Participants' exposure to residential greenness was characterized by the satellite-based normalized difference vegetation index (NDVI). Mixed effects logistic regression and mixed effects linear regression were performed to assess the associations of residential greenness with dyslipidemia and lipid levels. The median (interquartile range, IQR) of 3-year average NDVI_1000-m was 0.521 (0.089) units. Each IQR increase in NDVI_1000-m was significantly linked with increased odds of hyperbetalipoproteinemia (OR = 1.33, 95%CI 1.21-1.46). The same increment in NDVI_1000-m was associated with lower total cholesterol (TC) levels and increased low-density lipoprotein cholesterol (LDL-C) and high-density lipoprotein cholesterol (HDL-C) levels. For instance, the %changes in HDL-C levels was 0.71% (95%CI 0.17%-1.26%). The above relationships were partially mediated by reducing air pollution and lowering body mass index (BMI). Interaction effect analysis observed the greenness-lipid association was stronger in males than females (i.e., NDVI_1000-m-TC association). Long-term exposure to residential greenness was associated with odds of dyslipidemia and lipid levels in Chinese rural-dwelling adults, particularly among males. Considering the cross-sectional study design, more longitudinal studies are needed to identify the causal associations.

Nature and Children's Health: A Systematic Review

CONTEXT

Daily outdoor play is encouraged by the American Academy of Pediatrics. Existing evidence is unclear on the independent effect of nature exposures on child health.

OBJECTIVE

We systematically evaluated evidence regarding the relationship between nature contact and children's health.

DATA SOURCES

The database search was conducted by using PubMed, Cumulative Index to Nursing and Allied Health Literature, PsychInfo, ERIC, Scopus, and Web of Science in February 2021.

STUDY SELECTION

We followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. In all searches, the first element included nature terms; the second included child health outcome terms.

DATA EXTRACTION

Of the 10 940 studies identified, 296 were included. Study quality and risk of bias were assessed.

RESULTS

The strongest evidence for type of nature exposure was residential green space studies (n = 147, 50%). The strongest evidence for the beneficial health effects of nature was for physical activity (n = 108, 32%) and cognitive, behavioral, or mental health (n = 85, 25%). Physical activity was objectively measured in 55% of studies, and 41% of the cognitive, behavioral, or mental health studies were experimental in design.

LIMITATIONS

Types of nature exposures and health outcomes and behaviors were heterogenous. Risk of selection bias was moderate to high for all studies. Most studies were cross-sectional (n = 204, 69%), limiting our ability to assess causality.

CONCLUSIONS

Current literature supports a positive relationship between nature contact and children's health, especially for physical activity and mental health, both public health priorities. The evidence supports pediatricians in advocating for equitable nature contact for children in places where they live, play, and learn.

Green Space and Health in Mainland China: A Systematic Review

Non-communicable diseases (NCDs) have become a major cause of premature mortality and disabilities in China due to factors concomitant with rapid economic growth and urbanisation over three decades. Promoting green space might be a valuable strategy to help improve population health in China, as well as a range of co-benefits (e.g., increasing resilience to climate change). No systematic review has so far determined the degree of association between green space and health outcomes in China. This review was conducted to address this gap. Five electronic databases were searched using search terms on green space, health, and China. The review of 83 publications that met eligibility criteria reports associations indicative of various health benefits from more green space, including mental health, general health, healthier weight status and anthropometry, and more favorable cardiometabolic and cerebrovascular outcomes. There was insufficient evidence to draw firm conclusions on mortality, birth outcomes, and cognitive function, and findings on respiratory and infectious outcomes were inconsistent and limited. Future work needs to examine the health benefits of particular types and qualities of green spaces, as well as to take advantage of (quasi-)experimental designs to test greening interventions within the context of China's rapid urbanization and economic growth.

Subjective Proximity to Green Spaces and Blood Pressure in Children and Adolescents: The CASPIAN-V Study

Evidence favoring a beneficial association between greenness and blood pressure (BP) in adults is accumulating. However, children and adolescents have been understudied accordingly. Methodologically, the data on “exposure” to residential green spaces are commonly satellite-derived, including rare existing studies on the relationship between proximity to green spaces and BP in children. Despite perfectly obliterating subjective biases, remote sensing methods of greenness data collection fail to address pragmatic interaction with such settings. This study aimed to assess the relationship between subjective proximity to green spaces and average/elevated BP in children. Through our study, systolic and diastolic BPs of 12,340 schoolchildren living in CASPIAN-V study areas were examined and recorded. We performed surveys to obtain the data on their proximity to green spaces, defined as having access to such spaces within a 15-minute walk from their homes. Linear mixed-effects models with BP as the outcome variable and the measure of exposure to green spaces as fixed-effect predictor were applied. The analysis was adjusted for several covariates. We found that perceived residential proximity to green spaces was associated with −0.08 mmHg (95% confidence intervals (CIs): −0.58, 0.41; p value = 0.72) reduction in systolic BP and −0.09 (95% CIs: −0.49, 0.31; p value = 0.66) reduction in diastolic BP. We also observed statistically nonsignificant odds ratio of 1.03 (95% CIs: 0.76, 1.39), 0.96 (95% CIs: 0.80, 1.16), and 0.98 (95% CIs: 0.82, 1.16) for isolated systolic/diastolic hypertension and hypertension, respectively. Our observations remained consistent after adjustment for height, parental employment, low birth weight, parental obesity, single parent, and breastfeeding. In conclusion, subjective proximity to green spaces might not be associated with a lower mean BP in children. Well-designed studies applying both subjective and objective data should be performed to elaborate on the relationship further.