When the lung is compared to a tree, the air taken during respiration is carried to the alveoli, which are the most extreme points in the airways, and ensures that the carbon dioxide-rich blood, known as dirty blood, is re-oxygenated and oxygenated to the blood circulation in the body. Respiration and oxygenation process in the lung takes place in a closed environment. If there is a leak site due to any reason in the lung tissue, the inhaled air accumulates between the lung tissue and the chest wall.

Pneumothorax is the accumulation of air in the chest cavity as a result of a rupture in the lung. Accumulated air impairs the comfortable expansion of the lungs, making it difficult to breathe. Especially in smokers, air sacs called bullae form in the lungs, and when these burst, pneumothorax occurs. However, pneumothorax may occur not only due to the bursting of the bulla, that is, due to a disease in the lung (such as pneumonia, cancer, cyst) tearing the lung or perforation of the lung as a result of trauma.

The most common cause is trauma. In addition, it can also be seen as a result of spontaneous explosion of air sacs developed due to age and/or chronic diseases.