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Breathing Oxygen

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New Member
Aug 5, 2002
If you breathe pure oxygen before a dive in order to extend your bottom time. Do you have the same problem as you have in scuba where you cannot go below 10m (I don't know the exact limit but its somewhere around there)
Breathing pure oxygen..

Oxygen toxicity is the same wheter you breath it on surface or under water. By breathing oxygen does not sound like the wisest thing to do while freediving.

I think there has been a thread on same subject before. You should try to find that. And by oxygen toxicity Eric Fattah replied to the nitrox thread, about the exact same subject.

Freediving should be kept as freediving without any extra dangerous substances as pony botles, nitrox or pure oxygen.

Dive safe, breath air. Remember to hold your breath underwater.. ;)

1.6 atm

oxygen is considered toxic at 1.6 atm off partial pressure.
If you have 100% oxygen, you go down to 6 meters (i.e. 1.6 atm absolut):
100%* 1.6 atm=1.6 atm
If you use nitrox at 40% oxygen:
40/100*x=1.6 atm
x= 4 atm = 30 meter.

Remember at surface, pressure is 1 atm, ad 1 atm each 10 meter in salt water.

With air (21 % O2) You should stay at max depth 66 meters in the sea.

I believe that when you freedive, at the surface you have 21 % O2 in your lung but as you burn the oxygen into CO2 the oxygen percentage lower. Also, oxygen toxicity do not mean instant dead, but you start getting the following effects:
muscle twitching and spasm
nausea and vomiting
vision (tunnel vision) and hearing difficulties (tinnitus)
twitching of facial muscles
irritability, confusion and a sense of impending doom
trouble breathing, anxiety
unusual fatigue

So i think that breathing nitrox on the surface could help you, but personnaly, i would not do it, freediving is about relaxing and using the aquatic reflex that we all have, not about using enhancement technique.

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