GSTP1 and asthma: A total of 2,743 children had complete data on asthma, wheeze, potential confounders, NO2, ozone, PM2.5, PM2.5 absorbance, and at least one SNP of interest (n = 2,367 with GSTP1 rs1138272; n = 2,559 with GSTP1 rs1695; n = 2,318 with TNF rs1800629).