Definition of Collapsed lung:

A collapsed lung, or pneumothorax, is the collection of air in the space around the lungs. This buildup of air puts pressure on the lung, so it cannot expand as much as it normally does when you take a breath.

Causes, incidence, and risk factors:

A collapsed lung may result from chest trauma, such as gunshot or knife wounds, rib fracture, or after certain medical procedures.

In some cases, a collapsed lung occurs without any cause. This is called a spontaneous pneumothorax. A small area in the lung that is filled with air, called a bleb, ruptures, and the air leaks into the space around the lung.

Certain activities may lead to a collapsed lung. These include scuba diving, smoking marijuana or cigarettes, high altitude hiking, and flying.

Tall, thin people are more likely to a collapsed lung.

Lung diseases such as COPD, asthma, cystic fibrosis, tuberculosis, and whooping cough also increase your risk for a collapsed lung.