Risk factors

In general, men are far more likely to have a pneumothorax than women are. The type of pneumothorax caused by ruptured air blisters is most likely to occur in people between 20 and 40 years old, especially if the person is very tall and underweight.

Underlying lung disease or mechanical ventilation can be a cause or a risk factor for a pneumothorax. Other risk factors include:

• Smoking. The risk increases with the length of time and the number of cigarettes smoked, even without emphysema.
• Genetics. Certain types of pneumothorax appear to run in families.
• Previous pneumothorax. Anyone who has had one pneumothorax is at increased risk of another.