Fig. 4.
Estimated joint effects of NOS2 H1 haplotype, iNOS methylation and 7-day average PM2.5 exposure across the selected quantiles of FeNO distribution and its mean by race. In each panel, data are presented by number of H1 haplotype copy. The X-axis shows the combination of levels in methylation (first number in the bracket) and short-term PM2.5 exposure (second number in the bracket). Selected methylation levels are population average, 5% and 10% lower than averages, which are indexed by 0,-5 and −10, respectively. Selected PM2.5 exposure levels are population average, 5 μg/m3 and 10 μg/m3 higher PM2.5 exposure levels than average, which are indexed by 0, 5 and 10, respectively. The estimated joint effects when methylation levels are at population average, 5% and 10% lower than average are represented by black, red and green lines, respectively. a Non-Hispanic White Group b Hispanic White Group