The primary purpose of this study was to examine associations between NO2, PM2.5, PM2.5 – 10, PM10 and PM2.5 absorbance and the distance to a major road from a child's home address, as approximations of ambient air pollution exposure, and two bone turnover markers (osteocalcin and CTx, as surrogates of bone formation and resorption, respectively) in 10-year old children.