Association of greenness surrounding schools and homes with adiposity levels in children and adolescents

Wenzhong HUANG; Shuli XU; Qiuling FANG; Guanghui DONG

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Association of greenness surrounding schools and homes with adiposity levels in children and adolescents

VernacularTitle:家庭或学校植被水平与儿童青少年肥胖水平间的关联
Author: Wenzhong HUANG ¹ ; Shuli XU ² ; Qiuling FANG ² ; Guanghui DONG ²
Author Information

1. Department of Epidemiology and Preventive Medicine, School of Public Health and Preventive Medicine, Monash University, Melbourne, VIC 3004, Australia.
2. Department of Occupational and Environmental Health, School of Public Health, Sun Yat-sen University, Guangzhou, Guangdong 510080, China.
Publication Type:Specialcolumn:Forest,greenspace,andpopulationhealth
Keywords: greenness; normalized difference vegetation index; vegetation continuous field; children and adolescents; body mass index z-score; overweight
From: Journal of Environmental and Occupational Medicine 2022;39(1):23-29
CountryChina
Language:Chinese
Abstract: Background Evidence on the association between greenness and adiposity in children and adolescents is inconsistent and mostly from developed countries. Relatively limited evidence is from China. Objective To assess the association between greenness and adiposity in children and adolescents based on satellite remote sensing data. Methods From 2016 to 2018, a cross-sectional study was conducted among 52316 children and adolescents aged 5-18 years in three cities in the Pearl River Delta region of China. Basic sociological and demographic characteristics of the population and adiposity levels were collected through questionnaires. Land Remote-Sensing Satellite (Landsat) data and moderate-resolution imaging spectroradiometer (MODIS) products were used to quantify the greenness around the schools and homes, including normalized difference vegetation index (NDVI), vegetation continuous field (VCF), soil-adjusted vegetation index (SAVI), and enhanced vegetation index (EVI) calculated within 500 m and 1000 m buffers centered around the participants' homes or schools. A restricted cubic spline function was used to assess the exposure-response relationship. After categorizing greenness levels into quartiles with the first quartile as the reference, two-level generalized linear models were applied to assess the change in body mass index z-scores (zBMI) and the risk of overweight of children and adolescents in higher quartiles relative to the lowest quartile. In addition, counterfactual framework modelling was applied to assess the potential mediation effects of PM_2.5 and NO₂, and physical activity levels on the associations between greenness and adiposity levels. Results Of the 52316 children included, 8406 (16.1%) were overweight. A non-linear negative association of the level of greenness around the homes or schools and zBMI was found, with a significant lower zBMI in children and adolescents when a certain level of greenness was reached. After adjusting for confounders, the participants in the highest quartile had a significantly lower level of zBMI and a significantly lower risk of overweight compared with those in the lowest quartile of NDVI_{500 m} and VCF_{500 m}. The estimate change (\begin{document}$b$\end{document}) for zBMI was −0.07 (95%CI: −0.10-−0.04) and the odds ratio (OR) for overweight was 0.92 (95%CI: 0.85-0.99) for the students in the highest NDVI_{500 m} quartile based on home address compared to those in the lowest quartile. Significant negative associations were also observed when 1000 m buffer, SAVI, and EVI were used. The mediation analysis showed that PM_2.5 and NO₂ partially mediated the negative association of NDVI_{500 m} with zBMI , and the proportions of mediation were 50% (95%CI: 20%-80%) and 90% (95%CI: 50%-160%), respectively while no significant mediation effect was observed for physical activity level. Conclusion Higher levels of greenness surrounding homes or schools may be associated with a reduced risk of overweight and decreased zBMI in children and adolescents, and such associations may be partially mediated by reducing air pollutant concentrations.