[alexrom1207]

No carbon molecule = no urge to breathe EVER = blackout. Hyperventilation is a method of lowering the carbon amount, which delays the urge to breathe, but that leads to uncontrollable blackouts. Too bad. However, I did read somewhere that if you could completely eliminate the carbon byproduct then if you breathed pure oxygen and super-oxygenate your blood and lungs the human body could hold enough oxygen (with a low hr) to stay submerged for just over an hour. Obviously this is just a discussion of a physiological hypothetical, but it is cool to know what the human body is capable of.