A pneumothorax occurs when air leaks into the space between the lung and the chest wall, causing the lung to collapse. This can happen due to injury, such as a broken rib, or spontaneously without any obvious cause. Symptoms often include sudden chest pain and difficulty breathing, which can be alarming. Treatment for a pneumothorax may involve inserting a needle or chest tube to remove the trapped air and allow the lung to re-expand. In some cases, especially if the pneumothorax is small, doctors may simply monitor the situation. It's important to seek medical attention if you suspect a pneumothorax, as it can lead to serious complications.