Figure 2.

Percent change in club cell secretory protein levels from ages 6 to 32 years in association with an interquartile range increase in nitrogen dioxide (NO₂) exposure at birth, by race/ethnicity. All models include random effects for subject, fixed effects for visit, child’s sex and maternal smoking at enrollment, and an interaction term for child’s race/ethnicity and NO₂ exposure at birth. Participant counts include those with complete covariate, exposure, and outcome data. Percent change was calculated from the β coefficients according to methods for log-transformed outcome variables (24). CC16 = club cell secretory protein; CI = confidence interval.