This is a chronic condition that results in inflammation and fibrosis/scarring of the lung. Gradually, the alveoli become replaced by fibrotic tissue. When the scar forms, the tissue becomes thicker causing an irreversible loss of the lung's elasticity and its ability to perform gas exchange. This loss of lung elastance can be measured directly using the EMMS eSpira™ system, pulmonary mechanics, or indirectly using the non-invasive airway mechanics system.