OK, fair enough I will accept that some on-gassing does occur, and I should have been more circumspect in my wording. Anything greater than zero must necessarily qualify as 'some' because, unlike terms such as a 'couple', or a 'few' there is really no agreed upon interpretation of 'some'. You have a (very) small quantity of air in your lungs - maybe, 0.2 cf - you dive to 150 feet, the air compresses, the partial pressure of nitrogen rises from 0.79 to 4.3 so that there is actually some transfer of some nitrogen across the alveolar membranes to the blood stream. But, the absolute amount of nitrogen (what rteally counts, NOT the partial pressure) is so small, that the actual transfer is miniscule. Please, tell us all HOW MUCH nitrogen can be on-gassed. It is trivial. It has to be trivial, there is simply not enough air, and nitrogen in that air, to make any difference.
Using my earlier example - if you were to free dive to 150 feet 30 times, with a short surface interval between each dive, during which you filled you lungs with air, you would on-gas no more nitrogen than you would diving to 150ft (or 100 ft for that matter) on a nitrogen-free gas mixture, then breathing the entire contents of a 6cf bottle of air, before switching back to the nitrogen-free mixture and ascending to the surface. The amount is so trivial as to be totally irrelevant. It makes no physiologic difference. It goes back to the point of the OPs post. What his computer presents is completely, nonsensically, WRONG. So, tell us on the basis of actual numbers, on some actual actual understanding of physiology, and anything else other than citing reports that refer to 'anecdotal and retrospective' evidence (DAN paper), or a 15 y.o, undocumented report of a large series (all of two divers), how much nitrogen can possibly be on-gassed. MY point is, that it is PHYSICALLY IMPOSSIBLE to on-gas enough nitrogen, except under the most extreme circumstances (NOT what the OP described at all) to make any difference at all. In fact, once again, read what you cited: 'This is usually seen in divers who are making many deep dives in a short period of time with little surface interval.' and 'Free diving onloads N2, to a small degree, more or less depending upon the depth and time at depth ' Really? No s**t! What a specific, quantitative statement that elucidates how much nitrogen is actually on-gassed. OK, anything greater than zero is not zero, I agree. But the amount of nitrogen is trivial - there is simply not enough nitrogen in a single lungful of air to make any real difference. And EVERY report of some perceived issue with DCS in free divers is based either on extreme situations, or 'anecdotal evidence'.
'Anecdotal and retrospective' evidence can be used to suggest that bananas on a boat are bad luck. Certainly, the number of boat captains that believe that nonsense probably exceeds the number of physiologists who believe that 1-2 free dives before a scuba dive make any difference AT ALL in the nitrogen loading of the diver.
