Pulmonary fibrosis is a disease in which tissue deep in lungs becomes thick and stiff, or scarred, over time. The formation of scar tissue is called fibrosis. As the lung tissue thickens, your lungs can’t properly move oxygen into your bloodstream. As a result, your brain and other organs don’t get the oxygen they need.Sometimes doctors can find out what’s causing fibrosis. But in most cases, they can’t find a cause. They call these cases idiopathic pulmonary fibrosis (IPF). IPF is a serious disease that usually affects middle-aged and older adults. IPF varies from person to person. In some people, fibrosis happens quickly. In others, the process is much slower. In some people, the disease stays the same for years. IPF has no cure yet. Many people live only about 3 to 5 years after diagnosis. The most common cause of death related to IPF is respiratory failure. Other causes of death include pulmonary hypertension, heart failure, pulmonary embolism, pneumonia, and lung cancer.Genetics may play a role in causing IPF. If more than one member of family has IPF, the disease is called familial IPF. (source : NHI ).