The association between modeled NO2 and asthma prevalence was significant for carriers of the most common genotypes of NQO1 rs2917666 [odds ratio (OR) = 1.54; 95% confidence interval (CI), 1.10–2.24], TNFA rs2844484 (OR = 2.02; 95% CI, 1.30–3.27). This evidence concerns the gene TNF and asthma.