Long-term exposure to ambient air pollution and metabolic syndrome in children and adolescents: A national cross-sectional study in China

•Few studies have explored the effects of air pollution on metabolic syndrome (MetS) in children.•We studied 9,897 Chinese children in a national cross-sectional study.•Long-term exposures to PM2.5, PM10, and NO2 were positively associated with MetS.•PM1 and NO2 were related to elevated risk of fasting blood glucose and abdominal obesity.