If you or a friend or loved one has recently been diagnosed with pulmonary fibrosis (PF), you probably have a lot of questions. Very little is known about this chronic lung condition, despite the fact that approximately five million people suffer from it worldwide. We’ve put together a list of important facts about pulmonary fibrosis using information from the Pulmonary Fibrosis Foundation and gbhealthwatch.com.

Pulmonary fibrosis is a scarring of the lungs. 

Pulmonary fibrosis is scarring on the walls of the air sacs within the lungs. As this scarring builds up, it becomes more difficult for oxygen to reach the blood and results in respiratory failure.

MORE: 6 Less Common Symptoms of Idiopathic Pulmonary Fibrosis