free diving on 100% o2

[lowviz]

...//..., you would be using 02, further reducing the PP02....//... but I think we are just talking in theory...it's a fun discussion.

Can't reduce the PPO2, nothing to dilute the O2 with, no residual nitrogen. Only thing would be a lower lung volume...

 

[nimoh]

Can't reduce the PPO2, nothing to dilute the O2 with, no residual nitrogen. Only thing would be a lower lung volume...

wouldn't it be diluted with C02?

 

[lowviz]

Yes it would.

-but even at 10% CO2, you are still way,way out there in tox land...

Wikipedia:
In higher concentrations 1% (10,000 ppm) will make some people feel drowsy.^[77] Concentrations of 7% to 10% may cause suffocation, manifesting as dizziness, headache, visual and hearing dysfunction, and unconsciousness within a few minutes to an hour.^[79]

 

[fdog]

There is little in the literature regarding working breath hold dives using oxygen as a surface breathing gas. Most of what I've read indicates the possibility of CO2 retention; this could lead to a hypercapnic blackout under exercise. As deep technical divers know, hypercapnic blackouts are a very bad thing.

The phenomena you describe - blackout on ascent - is what is now known as a Deep Water Blackout. Shallow Water Blackout refers to excess CO2 blowoff during a breathold dive exclusively in shallow water, such as Dynamic Apnea in a pool.

Freediving apnea is a complex series of physiological responses. By using oxygen, you may be "fixing" one potential problem at the risk of introducing another....I would fear the loss of the subtle signs of loss of O2 fraction that warns us of overstaying, and, of an excessively high CO2 buildup.

The best fix for what you're trying to avoid (Deep Water Blackout) is a good buddy that escorts you to the surface from 10 meters.


All the best, James

 

[nimoh]

Yes it would.

-but even at 10% CO2, you are still way,way out there in tox land...

Wikipedia:
In higher concentrations 1% (10,000 ppm) will make some people feel drowsy.^[77] Concentrations of 7% to 10% may cause suffocation, manifesting as dizziness, headache, visual and hearing dysfunction, and unconsciousness within a few minutes to an hour.^[79]

I guess you're right, the dilution would be insignificant at best

 

[lowviz]

-still a fun collection of wild-a$$ guessing. All I know is, I won't try it...

 

[nimoh]

-still a fun collection of wild-a$$ guessing. All I know is, I won't try it...

me neither

 

[DevonDiver]

I only came to this thread because I thought that someone was giving out gratis deco gas... I'll slink away now...

 

[lowviz]

...//...... I'll slink away now...

Oh come on! You know you are dying to say something...

 

[ianr33]

Can't reduce the PPO2, nothing to dilute the O2 with, no residual nitrogen. Only thing would be a lower lung volume...

I don't think that's correct. Diver would be saturated with 1ATM worth of N2 at the surface. Fill your lungs with O2 and that N2 has to start offgassing,no matter if you are at the surface or 500 feet.