We don't know exactly why people get idiopathic pulmonary fibrosis, but researchers think it's a combination of genetic and environmental factors that cause the scarring in the lungs.
Doctors understand the causes of some pulmonary fibrosis conditions, such as hypersensitivity pneumonitis and those caused by autoimmune diseases, such as rheumatoid arthritis and systemic sclerosis. But it is not yet clear why some people develop these conditions, while others don't.
In some people, scarring of the lungs develops quickly, while in others it happens over a longer period of time. We don’t yet know why. Currently it is not possible to predict at the time of diagnosis how an individual person’s PF will behave.