Pneumothorax is a painful lung disease that is also known as a collapsed lung. The lungs contact the chest walls of a safe body. As air occupies the pleural space between the lung and the chest wall, the lung collapses partly or completely, resulting in a pneumothorax. Air enters the pleural area as a result of an illness or a lung leak. This collapsing of the lungs will put pressure on the heart, obstructing oxygenation and ventilation. Pneumothorax can be life-threatening at times.