One Breath at a Time

One risk that should be considered when making breath-hold excursions below the surface is what has often been termed “shallow water blackout.” A better term is “hyperventilation induced blackout.” This can occur when a diver takes several deep breaths in rapid succession or “hyperventilates” before submerging thinking that this will extend the time he can spend down there. Actually taking more than two breaths washes out the normal level of carbon dioxide (CO2) that is present in the lungs. At depth, the increasing build-up of carbon dioxide, not the lack of oxygen, is what triggers the need to breathe, signaling the end of the dive. Without the presence of enough CO2 to trigger the response, you can become unconscious from the lack of oxygen and drown. So never take more than two breaths before descending. After returning to the surface, spend a few minutes allowing your body to return to normal levels of both oxygen and carbon dioxide. When skin diving with a buddy, the safe practice is to have one buddy stay on the surface while the other one is underwater. Then rotate for another dive allowing time for the diver on the surface to fully ventilate between dives.