FN1 and pulmonary fibrosis: Our main findings provide evidence that exposure to chronic IH worsened BLM-induced lung injury inasmuch as IH: (i) doubled mortality after 21 days in BLM-treated mice; (ii) increased pulmonary inflammation as assessed by neutrophilic alveolitis and pulmonary edema during the first week following BLM treatment; (iii) induced lung cell apoptosis; and (iv) increased the severity of BLM-induced pulmonary fibrosis estimated by histological analysis, collagen and fibronectin mRNA transcript levels, and collagen content in lung homogenates.