Following exposure to control air, healthy individuals (A) and asthmatics (B) evidenced significant differences in oxylipin levels on a fatty acid class-specific basis for linoleates (LA; p = 0.004), arachidonates (AA; p = 0.008), docosahexaenoates (DHA; p = 0.045), dihomo-γ-linolenates (DGLA; p = 0.007), α-linolenates (α-LA; p = 0.035) and eicosapentaenoates (EPA; p = 0.045). Following exposure to subway air, only LA (p = 0.022) and AA (p = 0.013) were significantly different between healthy individuals (C) and asthmatics (D). No significant changes were observed in healthy individuals or asthmatics following exposure to subway air, relative to exposure to control air; (A) vs (C) and (B) vs (D), respectively. The unlabeled fatty acids (DGLA, α-LA, EPA and DHA) are all present at <5% and are presumably more representative of a lack of coverage in the analytical method rather than potential biological differences in relative abundance.