Pulmonary fibrosis is scarring of the lungs. The information here can be helpful to anyone facing one of the many types of pulmonary fibrosis, including the most commonly diagnosed, idiopathic pulmonary fibrosis (IPF). Some cases of pulmonary fibrosis occur without known cause (this is called idiopathic pulmonary fibrosis). Other cases are caused by exposure to environmental hazards (such as asbestos) and autoimmune diseases (such as rheumatoid arthritis). Some patients’ pulmonary fibrosis may result from lung damage caused by medications (such as chemotherapy). In other rare cases, genetics may predispose some patients to develop the disorder.