We natural log transformed NOx and markers of inflammation to
limit the influence of high concentrations and normalize distributions.
We computed unadjusted p-values and adjusted p-values for multiple
testing (q values) by controlling the false discovery rate (FDR) at 5%.
We used penalized splines (P-spline) in the generalized additive
mixed-model (GAMM) framework to assess potential non-linearity of
the relationships between inflammatory markers and exposure.