Pulmonary fibrosis is a condition that causes lung scarring and stiffness. It develops when the alveoli, tiny air sacs that transfer oxygen to the blood, become damaged and inflamed. Body tries to heal the damage with scars, but these scars collapse the alveoli and make the lungs less elastic. Changes in the lungs can also increase the blood pressure in the pulmonary artery. This condition, called pulmonary hypertension, makes the heart work harder and it may fail. It can result from many different lung diseases including sarcoidosis, drug reactions, autoimmune diseases, environmental allergies such as Farmer's lung, and exposure to toxic dusts and gases.
In Australia statistical analysis on pulmonary fibrosis given result as the three different methodologies of epidemiological studies were most commonly used, namely: 1) national registry databases, 2) questionnaire-based studies, and 3) analysis of the health care system’s own registry databases. The overall prevalence and incidence of IPF varied in these studies between 0.5–27.9/100,000 and 0.22–8.8/100,000, respectively. According to four studies the mortality and incidence of IPF are rising.