CNS not important anymore?

[crofrog]

Here are the DCIEM tables...

 

[nadwidny]

Who sais so?

David Sawatzky and Neal Pollock are 2.

 

[Pavao]

This leeds to even more questions than answers. Most of the statments contain "it seems" or similar.

Is there no scientific approach to this topic? NOAA limits were fixed may years ago and they still seem to exist. Is it really in theory only?

Modifying your question a bit may hint you in the direction of the current thinking on the subject.

Try and answer this question instead:
What was the scientific approach used by NOAA to arrive at their limits?

 

[rjack321]

Is there no scientific approach to this topic? NOAA limits were fixed may years ago and they still seem to exist. Is it really in theory only?

No because anyone with any money (commercial or military) is decoing in a chamber.

And there's basically no way to pass an ethics review having divers risking their lives in the water

 

[crofrog]

No because anyone with any money (commercial or military) is decoing in a chamber.

And there's basically no way to pass an ethics review having divers risking their lives in the water

Both the USN and DCIEM tables above are in water o2 tables…

 

[rjack321]

Both the USN and DCIEM tables above are in water o2 tables…

So? For any significant exposure they deco in chambers, not 8+ hours in homemade habitats.

 

[crofrog]

So? For any significant exposure they deco in chambers, not 8+ hours in homemade habitats.

They’re still doing dives that are well over 3000% on the cns clock. It’s really easy to find dives in the tables that’s have over 100 minutes on o2 in water.

If it was creating an undo risk to their divers or people where toxing all the time I’m sure they would have updated it.

 

[rjack321]

They’re still doing dives that are well over 3000% on the cns clock. It’s really easy to find dives in the tables that’s have over 100 minutes on o2 in water.

If it was creating an undo risk to their divers or people where toxing all the time I’m sure they would have updated it.

Sure except... you know that folks are doing those military or commercial deco exposures in water? in 2025?

Just because they are in the tables doesn't mean the experience is there behind them. In my own jurisdiction, commercial in-water deco is basically not done regardless of what the DCIEM tables might say. At least locally, I suspect in the last decade+ 1,000s more tunnel excavators were decompressed compared to commercial in-water divers. None of those construction workers even got wet.

 

[sea_ledford]

There was a panel discussing this at the last AAUS symposium. I posted a followup on a different thread (below). I'm not sure when the official consensus statement will be coming out, but the decimation of NOAA probably isn't helping things.

TL;DR - 4 hours working + 4 hours deco/resting at PO2 of 1.3 will be the updated recommendation.

Info Post in thread 'Some History of the NOAA Oxygen Limits'

Mar 31, 2025

I did end up attending the workshop. I certainly can't definitively report what will be in the consensus statement, but I'll relay my understanding of it.

The primary emphasis was on long duration moderately high po2 levels below 1.4. The data set that established the NOAA O2 limit tables was from military combat swimmers using pure O2 units and the current limits in the 1.6 and above range, the panelists all agreed, were appropriate as they are.

The problem with all the lower limits were they were just a "well, that seems about right" seat of the pants interpolation of the higher...

• sea_ledford

• 
•