Research provides considerable evidence of nature-related health benefits for humans. Still scarce in the research are studies investigating the effects of greenness -- especially school-based greenness -- on childhood obesity. This study addressed this gap in the literature by exploring the association between school-based greenness and adiposity in children and adolescents in China.
The study involved 94 schools and 56,620 students in 7 provinces in China. All participating children were between the ages of 6 and 18. Trained nurses collected child data on three different occasions consisting of height, weight and hip and waist circumference. The average of the three measures were used in the analysis of the data for this study. Two different satellite-generated measures of school-based greenness were used: the Normalized Difference Vegetation Index (NDVI) and the Soil Adjusted Vegetation Index (SAVI). The average of these two values in 100-, 500-, and 1,000-meter buffers around each school's location was used in the data analysis. Self-reported student data included socio-demographic and lifestyle information, including information about levels of physical activity. Additional data for this study focused on children's estimated exposure to air pollution while at school.
Over 15% of the children were overweight; over 9% obese. Boys were more likely to be overweight/obese than girls. Children who were obese generally engaged in less physical activity and tended to live in the northern parts of China. School-based greenness indicators varied significantly across different schools in China. Children with healthier weight were more likely to attend greener schools than overweight/obese children. The associations were stronger among boys, older students, city-dwellers, and children whose parents had lower levels of education. Air pollutants seemed to partially mediate the effects of exposure to greenness on childhood obesity. Physical activity levels did not.
While this study provides some indications that greenness around schools is associated with healthier weight for children and adolescents, further research is needed to confirm the results.