Beta estimates are presented per interquartile range increase for the continuous exposures (IQR, 6.7 μg/m3 for NO2, 4.0 μg/m3 for PM2.5, 2.5 μg/m3 for PM2.5 – 10, 4.9 μg/m3 for PM10, 0.4 × 10−5 m−1 for PM2.5 absorbance, and 442.2 m for distance to a major road, in the total data). For the models which include distance to a major road as a dichotomized variable, the coefficients reported represent an increase in bone turnover marker concentrations for children living close to a major road, compared to those living >350 m away from a major road. All results are presented as regression coefficients with corresponding 95% confidence intervals (CI). P-values below 0.05 were used to indicate statistical significance.