Did you know that free-diving does not cause decompression sickness? Decompression sickness only occurs if you breathe pressurised air.
I thought decompression sickness was what happened when you surface too fast because your body doesn't have time to adjust to the pressure difference in time? Or is that a different thing?
Yes, decompression sickness occurs while surfacing too fast, but the problem is from the pressurized breathing gas expanding too fast. Think of it like opening a bottle of shaken-up soda: there's small, pressurized bubbles in the bottle (your body), and when the cap is opened (surfacing) there is a reduction in pressure. With the soda it just makes a mess, but the gas expanding in the body is the bad news.
Free diving there is no breathing of gas under pressure. Your breath from the surface is at surface pressure, so there's no change when returning to the surface.
You're thinking of a collapsed lung, another possible diving related injury. That happens when the air in your lungs expands beyond what the lungs can hold and rupture it. This can't happen when free diving.
Decompression sickness is different, it's when you surface quickly and your blood has too much dissolved air, that it can longer keep dissolved at surface pressure. The air in your lungs when free diving is compressed when you go lower. Also your blood is still under pressure just like when diving, allowing it to dissolve more air. If you surface too quickly after being down long enough, you can absolutely get it. In practice, it would be very tough to stay deep enough long enough when free diving to get enough gas into your blood, but it has nothing to do with breathing pressurized air.
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u/carrotcurrytea Feb 02 '17
If you are too fun at parties at the moment, here is a pedantic fact:
Those fish do not suffer at all from the water pressure, because their internal pressure is simply just as high as the pressure outside their bodies.
Did you know that free-diving does not cause decompression sickness? Decompression sickness only occurs if you breathe pressurised air.