Pulmonary fibrosis

Pulmonary fibrosis, in pulmonary medicine, is a irreversible and progressive disease in which the air sacs of the lungs become stiff and hard to fill, making breathing increasingly more difficult until death ensues. A number of forms of the disease come from industrial exposure to coal dust or sand blasting; other cases are due to drug reactions, and sometimes the cause is never known.

Formally, it is a "process in which normal lung tissues are progressively replaced by fibroblasts and collagen causing an irreversible loss of the ability to transfer oxygen into the bloodstream via pulmonary alveoli. Patients show progressive dyspnea finally resulting in death."