Risk of CO (versus incorrect O2 tank levels)

[Abdullah]

---

---

A ScubaBoard Staff Message...

This thread has been split as the result of an off-topic discussion from the Accidents and Incidents Forum on the death of a diver who mix in his tank was different from what he believed it to be. The original discussion may be found here: http://www.scubaboard.com/forums/ac...ed-his-brother-died-today-ginnie-springs.html
Marg, SB Senior Moderator

---

The question for the typical OW recreational diver (who probably doesn't own his own analyzer) is what the risk of an inadvertent EANx mix really means to his safety. A recreational dive in the air NDL range is not likely to be endangered by an accidental one-off use of a 32% or 36% blend marked as air. The chances of a rich deco mix or 100% O2 ending up in an OW rental air tank are pretty remote. Can you honestly say that the risk is significant enough to the predominant population of OW recreational divers to warrant having everyone go out and drop $300 on an O2 analyzer? Seems like an over reaction to me.

If you're going to promote air analysis for the masses, I think the risk of a CO hit is greater and more immediately life threatening to any diver than an accidental EANx fill in their air tank. Especially in areas where the fill operator is stressed or the compressor maintenance is questionable.

 

[syntaxerrorsix]

That's probably a good guess on the air tank analysis rate. What do you guess the incident rate is on air tanks that contain some type of mixed gas by mistake? My guess is that it's less than your analysis rate, but I have never seen any mishap statistics to support any conclusion about the actual risk of getting a blend in an air tank. Most of the anecdotal data is related to blending errors (wanted 32%, got 29%), not diving an air tank but got O2 by mistake.

The question for the typical OW recreational diver (who probably doesn't own his own analyzer) is what the risk of an inadvertent EANx mix really means to his safety. A recreational dive in the air NDL range is not likely to be endangered by an accidental one-off use of a 32% or 36% blend marked as air. The chances of a rich deco mix or 100% O2 ending up in an OW rental air tank are pretty remote. Can you honestly say that the risk is significant enough to the predominant population of OW recreational divers to warrant having everyone go out and drop $300 on an O2 analyzer? Seems like an over reaction to me.

If you're going to promote air analysis for the masses, I think the risk of a CO hit is greater and more immediately life threatening to any diver than an accidental EANx fill in their air tank. Especially in areas where the fill operator is stressed or the compressor maintenance is questionable.

I think a CO hit is just as unlikely as an OW air diver being given nitrox and toxing. Just about zero.

 

[redacted]

I think a CO hit is just as unlikely as an OW air diver being given nitrox and toxing. Just about zero.

I have seen reports of a number of incidents of OW divers dying from CO in an air/EAN tank. I have never seen a report of an OW diver on Air toxing from too much O2.

 

[syntaxerrorsix]

I have seen reports of a number of incidents of OW divers dying from CO in an air/EAN tank. I have never seen a report of an OW diver on Air toxing from too much O2.

That number is probably under 10. Given the amount of OW divers and diving worldwide that's essentially zero. "Bad air" is an extremely rare event.

 

[Abdullah]

I think a CO hit is just as unlikely as an OW air diver being given nitrox and toxing. Just about zero.

I analyze every tank for CO. I have had several in the 10 - 20 ppm range and one in the 80's (<2 ppm is my comfort zone).

The farther you get from the well regulated fillers in the US and the UK, the greater your chances of getting a polluted fill.

 

[syntaxerrorsix]

I analyze every tank for CO. I have had several in the 10 - 20 ppm range and one in the 80's (<2 ppm is my comfort zone).

The farther you get from the well regulated fillers in the US and the UK, the greater your chances of getting a polluted fill.

More power to you. I too would feel it prudent if my fills came from questionable source. I don't however have that issue and throughout the world there doesn't seem to be a quantifiable amount of bad air cases to concern me in the least. The list is so small no one can come up with any sort of conclusive database. Sort of like winning the lotto or getting hit by lightening except we actually track that information.

 

[AggieDiver]

More power to you. I too would feel it prudent if my fills came from questionable source. I don't however have that issue and throughout the world there doesn't seem to be a quantifiable amount of bad air cases to concern me in the least. The list is so small no one can come up with any sort of conclusive database. Sort of like winning the lotto or getting hit by lightening except we actually track that information.

We really have no idea how many dive fatalities result from bad air, mainly because it is fairly rare for the air to actually get tested after the incident. In many locales, there is a much higher interest in concealing the fact that somebody died than actually figuring out why. And if testing does turn out to indicate bad air, the locals are often going to protect the operator instead of publicizing the results. So just because we don't hear about it doesn't mean it isn't happening.

 

[syntaxerrorsix]

We really have no idea how many dive fatalities result from bad air, mainly because it is fairly rare for the air to actually get tested after the incident. In many locales, there is a much higher interest in concealing the fact that somebody died than actually figuring out why. And if testing does turn out to indicate bad air, the locals are often going to protect the operator instead of publicizing the results. So just because we don't hear about it doesn't mean it isn't happening.

My apologizes but I don't buy into tinfoil hattery. We have plenty of databases that log dive accidents and there causes. What we don't have is any empirical evidence that bad air is causing enough deaths to form any thing conclusive or to even start making a list.

If you got a source to anything other than the 4 or 5 incidents that can be Googled I'm all eyes.

 

[nimoh]

We really have no idea how many dive fatalities result from bad air, mainly because it is fairly rare for the air to actually get tested after the incident. In many locales, there is a much higher interest in concealing the fact that somebody died than actually figuring out why. And if testing does turn out to indicate bad air, the locals are often going to protect the operator instead of publicizing the results. So just because we don't hear about it doesn't mean it isn't happening.

true, but it also doesn't mean that it is happening

 

[AggieDiver]

My apologizes but I don't buy into tinfoil hattery. We have plenty of databases that log dive accidents and there causes. What we don't have is any empirical evidence that bad air is causing enough deaths to form any thing conclusive or to even start making a list.

If you got a source to anything other than the 4 or 5 incidents that can be Googled I'm all eyes.

So if it can't be googled then it isn't happening? Wow...rigorous research sources you have there. How many dive fatalities have their cause listed as "drowning"? Go google that and you will start to see the problem. When somebody fails to surface on a dive, and is later found on the bottom, or the surface dead, it is unfortunately not very common to have the tanks analyzed. In the US, sure it happens quite frequently...in Indonesia or Roatan or Palau? Not so much. And what about the cases where the tank is empty by the time the body is found and there is nothing to test? There was a very well discussed case in Baja Mexico here a year or so ago...lots of evidence pointed to bad air in that case. Go google it and tell me how many places you found the results of the "testing" that the police were supposedly doing with the air and the gear. They have been "testing" the gear for quite some time now, and as far as I know, the cause of death is still not been published. But the scuba shop that may or may not have filled the tanks is no longer a PADI endorsed shop. So you tell me whether the police are dragging their feet or avoiding publishing info that might hurt the locals? It seems like it would have been a very quick and easy thing to test the tanks and then either release a statement saying the tanks were clean...or the tanks had XX ppm CO. But nothing has ever been publicized. I wonder why?

In many incidents, by the time a lawyer or stateside investigator asks for a tank to be analyzed, it has already been stripped off of the gear and put back into the pile of tanks to be refilled. Sure, the gear may be tested...and the first thing they do to test it is take it off of the tank and put it on a new one to see if it works. But rarely is the tank itself tested. The coroner inspects the body, finds water in the lungs, and lists the cause as "drowning", and that is it. So the lack of google evidence of CO involvement doesn't mean it isn't happening. I really do mean it when I say we just don't know. I am not advocating a position that it is a huge problem...I am simply saying that assuming it isnt a problem because you are not seeing stories on the internet is a logical fallacy, because there are many other reasons for those stories not to be there.

I want to ignore your comment about tinfoil hattery, but I find that I can't just let it be. You really think that places like Cozumel or Roatan or elsewhere that dive tourism is big are going to go out of their way to publicize a dead diver? We generally get a story about the initial incident, and that is it. When the coroner or whoever makes any further findings known (if they ever do), they don't contact news sources and no follow up stories get published. The only way we generally get any updates at all are when family members or friends post about it on sites like this. There is just no real means by which the results of air testing on a tank involved in a scuba fatality would get routinely posted in a place where google would even pick it up. The lack of followup information about fatalities is part of why this forum exists...so that we can collect information about what happened (or may have happened) and hopefully learn something from it. So if you think that just because you don't read about it happening on google it means that it isn't happening, you might want to look at your own hat, because it might be a bit sandy from burying your head too far.