| Idiopathic pulmonary fibrosis (15 to 40 percent) |
| Cryptogenic organizing pneumonia (40 to 70 percent) |
| Inorganic dust diseases |
| Asbestosis |
| Silicosis |
| Cigarette smoking (<10 percent) |
| Pulmonary Langerhans cell histiocytosis (Histiocytosis X) |
| Hypersensitivity pneumonitis (acute) |
| Sarcoidosis (advanced) |
