PAH and pulmonary arterial hypertension: The increase in PIG-A MF in the PAH-exposed workers was associated with OH-PAH metabolites of 2-OH-Flu (P = 0.032, r = 0.268), 2-OH-Phe (P = 0.022, r = 0.286), 3-OH-Phe (P = 0.0312, r = 0.270), and 4-OH-Phe (P = 0.018, r = 0.296).