Posted by TomR on April 12, 2005 at 17:13:47:
In Reply to: oxygen posted by scott on April 12, 2005 at 09:03:03:
Spoiler: This is probably more info than desired, but here you go...
In addition to cardiovascular rate, depth greatly affects the number of oxygen molecules you suck down. As your depth increases, the pressure of the air mixture you are breathing increases proportionally. For example, if you descend to 33ft., the atmospheric pressure doubles and you are breathing twice as many oxygen particles per breath (as well as twice as many of all the other particles in your breathing mixture - proportions stay the same, but absolute number of particles inhaled increases).
One of the dangers of extremely deep diving with standard air mixtures is a buildup of too many oxygen particles that results in oxygen toxicity, a seizure like state that can cause drowning. Needless to say, it is dangerous to dive beyond recreational dive table limits or with high oxygen content mixtures without proper training.