Importantly, log2 fold change values of individual linked genes including AHRR, CYP1A1, CYP1A2, CYP1B1, IL6, UGT1A3, and UGT1A4 demonstrate similar expression levels across seasonal PMs (Fig. 3G/5A), suggesting universal effects on xenobiotic metabolism due to PM exposure with or without subsequent infection with influenza. The gene discussed is UGT1A4; the disease is influenza.