AHRR expression induced by carcinogenic polycyclic aromatic hydrocarbons, which are increased in the lung tissue of smokers,22 associates with AHRR DNA methylation in blood,14,23 lung tissue,24 and BAL cells.16 Some of the identified BS-DMPs in MS BAL cells were also found significantly associated with smoking in blood from MS patients.14 Interestingly, smoking exerted a stronger impact in BAL cells compared to blood at most overlapping DMPs, for example, at AHRR/EXOC3 locus. Here, EXOC3 is linked to myeloid sarcoma.