JoshNZ
Registered
Hi guys/girls,
Hopefully you don't mind a quick stop to resolve a subject that's come up several times for me and some over the years!
I know you're not supposed to freedive with nitrogen dissolved in blood after diving, but I don't exactly understand why, despite numerous explanations. I do have a reasonable understanding of gas laws, I know nitrogen is dissolved in blood and ascents must be slow to allow this gas to offload without coming out of solution and causing illness. I also understand after a safe ascent when sitting in an appropriate pressure group at the surface, the pressure gradient between gas tension in blood and partial pressure in atmosphere is low enough that bubbles will not form. So, what is it about a moment at depth before returning to this state that can unfurl this situation?
It would make sense (in my uneducated mind, at least!) if your dissolved nitrogen at the surface is at a safe concentration, momentarily increasing pressure and then decreasing back to this same surface pressure, should change nothing.. I know some gas will be dissolved at depth from the one lungful of compressed gas you are holding but I thought this was insignificant.
Why does going from a safe ambient pressure, to depth, and back to the same safe pressure without loading more gas cause issues?
Not here looking for an excuse to be an idiot, it's just something I've wanted to understand and have finally gotten around to asking the question!
Thanks in advance as always,
Josh
Hopefully you don't mind a quick stop to resolve a subject that's come up several times for me and some over the years!
I know you're not supposed to freedive with nitrogen dissolved in blood after diving, but I don't exactly understand why, despite numerous explanations. I do have a reasonable understanding of gas laws, I know nitrogen is dissolved in blood and ascents must be slow to allow this gas to offload without coming out of solution and causing illness. I also understand after a safe ascent when sitting in an appropriate pressure group at the surface, the pressure gradient between gas tension in blood and partial pressure in atmosphere is low enough that bubbles will not form. So, what is it about a moment at depth before returning to this state that can unfurl this situation?
It would make sense (in my uneducated mind, at least!) if your dissolved nitrogen at the surface is at a safe concentration, momentarily increasing pressure and then decreasing back to this same surface pressure, should change nothing.. I know some gas will be dissolved at depth from the one lungful of compressed gas you are holding but I thought this was insignificant.
Why does going from a safe ambient pressure, to depth, and back to the same safe pressure without loading more gas cause issues?
Not here looking for an excuse to be an idiot, it's just something I've wanted to understand and have finally gotten around to asking the question!
Thanks in advance as always,
Josh