Background

Childhood obesity is a global health issue, and limited evidence suggests that air pollution may be a contributing factor. This study aims to examine whether exposure to fine particulate matter (PM_2.5 ) is associated with obesity status in a nationally representative sample of schoolchildren in China.

Methods

The study population consisted of 41,439 schoolchildren of 6-17 years old, recruited from 30 provinces in China using a multi-stage stratified sampling method. Weights and heights were measured for all the participants, and sociodemographic information was collected using a questionnaire. The obesity status was classified following the Chinese national standards. The PM_2.5 exposure was estimated as the 5-year average concentration at the school location for each participant. The association between obesity status and PM_2.5 exposure was examined using weighted logistic regressions adjusted for potential confounders.

Results

The prevalence of normal weight, overweight, and obesity were 78.5%, 12.4%, and 9.0%, respectively. PM_2.5 exposure averaged 59.8 ± 17.6 μg/m³ with a range of 30.5-115.2 μg/m³ among all the participants. The risk of obesity increased by 10.0% (95% confidence interval: 3.0-16.0%) per 10 μg/m³ increase in PM_2.5 exposure. The PM_2.5 -associated risk was significantly elevated in older age groups and children living in urban areas (interaction p-values < 0.05).

Conclusions

This national survey revealed that approximately 1 in 5 Chinese schoolchildren were overweight or obese. Exposure to PM_2.5 in the ambient air was significantly associated with childhood obesity. The findings suggest the need for further research to uncover the roles of PM_2.5 exposure in childhood obesity development.