The Risks of Ascent
DeeperBlue.net – December 2, 2002
“For an equivalent change in depth the risk of barotrauma is greatest near the surface, a fact explained by Boyle’s law. A breath-holding free diver rising from 33 feet to the surface experiences a change in ambient pressure from two to one atmospheres. If the lungs fully expand within the chest cavity the lung volume will double. By contrast, a 33-foot rise from 99 to 66 feet depth (i.e., from 4 to 3 atmospheres) would maximally increase a free diver’s lung volume only 33 percent, posing less risk of a barotrauma.” – Erik Seedhouse
