Good News for Freedivers: Lung Squeeze Doesn’t Leave a Mark

Elite freediving puts the lungs under intense pressure, sometimes leading to pulmonary barotrauma (PBT), or “lung squeeze”—an acute injury that can cause coughing, discomfort, and even blood in the sputum.  There has been concern that repeated episodes of PBT might also cause lasting damage. However, there is a large gap in our understanding oft he long-term impacts of lung squeeze.

To explore this, researchers performed high-resolution chest CT scans on 14 elite freedivers (13 men, 1 woman), most of whom had experienced symptoms of lung squeeze. The severity of their worst episode was self-reported using a four-point scale: from no symptoms to frank hemoptysis (blood-filled sputum). Their scans were compared to those of 17 healthy, non-divers (14 men, 3 women) matched for age and body size.

Twelve of the 14 divers reported previous symptoms of PBT, with 8 experiencing coughing blood, yet none of them showed pathological changes on imaging. While some scans showed minor, non-specific findings—like small blebs or subpleural lines—these were also present in the control group and considered within normal limits. There were no signs of fibrosis, emphysema, or other structural lung disease.

The results contradicted the researchers’ hypothesis: even in freedivers with a history of significant symptoms, there was no radiologic evidence of long-term lung damage. The authors suggest that this may be due to the lungs' capacity to recover, the elite fitness level of the participants, or limitations of imaging in detecting microscopic damage.

While the study has limitations — such as a small sample size and lack of lung function tests — it offers reassurance: in healthy, asymptomatic freedivers, a history of lung squeeze does not appear to cause lasting harm.