Lesson 1, Topic 1
In Progress

Carbon Dioxide Intoxication


The most usual cause of carbon dioxide (CO2) poisoning in the practice of diving is the poor respiratory technique (shallow breathing), which causes a retention of this gas in the body.

Another cause of CO2 poisoning is the excessive tiredness of the diver (exhaustion), already existing when entering the water. This fatigue can also be caused by sea conditions (current, cold water, poor visibility, ripple), fear, insecurity, lack of preparation, incorrect use or failure of the equipment (regulator with insufficient flow or continuous inflow) or an unexpected danger situation.


The diver should be concerned about the expiratory phase, which should be active and prolonged. You must make deep exhalations to release the CO2 produced as much as possible.


Phase 1

  • Difficulty breathing (breathing increasingly accelerated).
  • Anxiety.
  • Headaches.
  • Dizziness and nausea.

Phase 2

  • Palpitations.
  • Muscle tremor.
  • Bluish lips and extremities.
  • Seizures.
  • Loss of consciousness (Loss of consciousness can lead to death by drowning).

If the diver is submerged when he begins to experience difficulty breathing, he/she must stop all movements and control breathing by concentrating on the expiratory phase, which should be active and prolonged.

After calming down and regularizing your breath, you should climb a few meters slowly. If he doesn’t improve, he should return to the surface after warning his diving partner that he is not feeling well so he can accompany him.

This type of intoxication causes most surface drowning deaths. In extreme situations, the diver loses control of breathing, which becomes faster and shallower, further increasing the level of CO2 in the body, until it reaches total control. At this point, the diver desperately tries to stay on the surface, pulls off the mask, removes the regulator, does not respond to the diving companion, forgets to fill the vest and drop the ballast belt. He then panics, which can quickly lead to a drowning situation.

Upon reaching the surface the diver must fill the vest, to float without making any effort. If necessary, you should not hesitate to drop the ballast belt, standing still until they collect it. You should also not hesitate to ask for help by means of a sound signal and the appropriate visual signal.

After climbing aboard, the diver should rest in a well-ventilated place. Usually the improvements occur after a while.

If possible, 100% oxygen should be administered with a 15l/min output, as oxygen treatment substantially reduces recovery time.