Can you tell me how do lungs collapse and what prevents it?

Trauma or pressure: How do lungs collapse? There are different reasons such as trauma to the chest but also altitude changes mainly during diving. The mechanism has to do with not allowing inhaled air under pressure to come out on the ascent to the surface leading to expansion of the lungs with rupture of alveoli leading to lung collapse. Avoid diving when congested, avoid holding air on ascent for prevention