Here, we evaluated the direct effects of benzo[a]pyrene (BaP), a representative PAH, on the methylation status of the 5 ́-flanking region and gene expression of IFNγ and IL4 in Jurkat T cells and two adenocarcinoma cell lines (A549 and H1793) as in vitro models of epigenetic responses of immune or airway cells to PAH exposure. Here, IFNG is linked to pulmonary arterial hypertension.