Risk of CO (versus incorrect O2 tank levels)

[syntaxerrorsix]

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.

Got it, you've got no empirical evidence to add.

---------- Post added August 22nd, 2013 at 06:51 PM ----------

Wanna buy an analyzer?

 

[AggieDiver]

Which was exactly the point of my first post on the matter...I said we don't know how many fatalities are caused by bad air. That is because the tanks are not tested in most incidents, and even when they reportedly are tested (as in Rhonda Cross' case), the authorities don't often publicize the results. Your contention is that because we never hear about testing results on the internet, we can assume it is not a problem. Neither of us has any empirical evidence that bad air is or is not a problem, but you are the only one jumping to a conclusion that it is not a problem based on that lack of evidence.

If we had a full data set and testing, and no evidence of bad air, I would agree with you. But we have a woefully incomplete dataset, where most incidents don't involve testing the tanks, so I conclude that we just don't know if it is a problem or not.

Lets try this. If you had 100 single vehicle accidents where somebody died wrapping their car around a tree. And they only tested the body for alcohol in 10 of the 100 cases. If they found alcohol in 5 of the 10, would you conclude that alcohol was not a problem because only 5 out of 100 showed empirical evidence that alcohol was involved? Hopefully not. The proper conclusion to draw is that the dataset you were working with is insufficient to draw any concrete conclusions, but lean towards assuming alcohol could be a problem because it showed up in 50% of the small number of accidents where testing was performed.

 

[syntaxerrorsix]

Which was exactly the point of my first post on the matter...I said we don't know how many fatalities are caused by bad air. That is because the tanks are not tested in most incidents, and even when they reportedly are tested (as in Rhonda Cross' case), the authorities don't often publicize the results. Your contention is that because we never hear about testing results on the internet, we can assume it is not a problem. Neither of us has any empirical evidence that bad air is or is not a problem, but you are the only one jumping to a conclusion that it is not a problem based on that lack of evidence.

If we had a full data set and testing, and no evidence of bad air, I would agree with you. But we have a woefully incomplete dataset, where most incidents don't involve testing the tanks, so I conclude that we just don't know if it is a problem or not.

Lets try this. If you had 100 single vehicle accidents where somebody died wrapping their car around a tree. And they only tested the body for alcohol in 10 of the 100 cases. If they found alcohol in 5 of the 10, would you conclude that alcohol was not a problem because only 5 out of 100 showed empirical evidence that alcohol was involved? Hopefully not. The proper conclusion to draw is that the dataset you were working with is insufficient to draw any concrete conclusions, but lean towards assuming alcohol could be a problem because it showed up in 50% of the small number of accidents where testing was performed.

Let's try this... if CO was major cause for concern it wouldn't be limited to obscure posts on the most prolific diving boards across the globe let alone major worldwide search engines.

---------- Post added August 22nd, 2013 at 08:23 PM ----------

Feel free to dramatize this as you see fit.

 

[DandyDon]

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

And why would you think that? Is your thinking based on any study of the risk, at all...??

It's always interesting when a dive pro objects to improving safety, but we see it with this risk - just too much old school thinking. But then in the old school, they could not test tanks for CO as the technology was not available and affordable. Now that it is, it's safer to test than dive on hope.

AggieDiver has done a great job of addressing your comments, but let me add this from another discussion

The risk of CO poisoning may be much higher than we'd like to admit basically because no one is doing a carboxyhemoglobin (COHb) in all dive fatalities, however if you look at the Dr. Caruso’s UHMS retrospective dive fatality abstract posted earlier 3 percent of the divers whose COHb concentration was checked at death had an anomalous level. Three percent is certainly well above the frequency one would expect for a potentially lethal contaminant that is "barely quantifiable" and far greater than the risk of dying from DCS.

We can also try and assess the frequency of CO contamination in our breathing air from another direction and that is by asking the compressed gas analytical laboratories what their frequency of test failure is for CO at the 10 ppm level. These labs receive thousands of dive air samples a month from fill stations all over the globe so this number would be the best real-time indicator as to the extent of the contamination problem.

This question was posed to the labs by Bob Rossier, an ex-NASA life support systems engineer, in 1998 and 2004 and reported in the DAN Diver Alert magazine. I have attached his 2004 DAN Diver Alert article which indicates that when Lawrence Factor and TRI Laboratories, two of the largest compressed gas laboratories in the USA, were contacted and asked the frequency of CO contamination in dive air alone (fire service compressed air has a CO failure rate about 0.1 %) both labs reported independently in 2004 that the failure rate was 3 to 5 percent, an incredibly high percentage considering the high toxicity of this contaminant and potential for death in the underwater environment. In 1998 these same lab directors were asked the CO failure rate in diver compressed air and reported it was 5 to 8 percent so things have improved somewhat since that time but not by much.

The point is though that if someone told you that there was a 5 percent chance the tank of dive air you might use could contain CO at a concentration above 10 ppm I think you would be hard pressed to call that "barely quantifiable" in fact a rationale person would request that their fill station install a CO monitor or that the individual diver would purchase a personal CO analyzer.

It does not surprise me at all that we are hearing of more and more CO-contaminated tanks plus CO-related injuries and deaths as the awareness of the problem and in-field tank testing has increased 100 fold with the availability personal CO analyzers. In the end the frequency of these CO incidents in the field should reflect the rate of CO contamination identified by the labs testing the compressed air from the same field on a daily basis. Only when a COHb concentration is done in all dive fatalities will we also see the frequency of anomalous COHb levels trend towards that 3 percent level.

In 2009 I spoke with these same lab directors again and they confirmed that nothing had changed since 2004 indicating that we in the dive community still have a 3 to 5 percent chance of receiving a tank of compressed air with CO contamination > 10 ppm. The samples sent to Lawrence Factor and TRI come from all over the world so this is a global dive industry problem but worse in those geographical regions where high ambient temperatures conspire to allow poor compressor installations to overheat and intermittently burn (autoignite) the compressor oil.

If it was reported that that our national blood supply contained HIV or Hep C contamination at a rate of 3 to 5 percent not only would the population be up in arms and demand rigorous testing to eliminate that risk, but I doubt you find to many potential transfusion recipients cavalierly saying this was a negligible risk and that they would rather forgo HIV or Hep C testing and just accept the risk of contracting a potentially lethal disease.Yet sadly in the dive industry that is exactly what we still hear today despite the facts indicating the CO contamination risk is quantifiable in our dive air and runs about 3 to 5 percent.

 

[syntaxerrorsix]

And why would you think that? Is your thinking based on any study of the risk, at all...??

It's always interesting when a dive pro objects to improving safety, but we see it with this risk - just too much old school thinking. But then in the old school, they could not test tanks for CO as the technology was not available and affordable. Now that it is, it's safer to test than dive on hope.

AggieDiver has done a great job of addressing your comments, but let me add this from another discussion

Because I can read the annual statistics from the agencies that collect such information. She didn't address anything other than feelings and one or two reported results. She also "feels" that global results aren't reported which they are. I can quote source material from all reliable and they all say the same thing. Insufficient data. We don't have that problem with any other diving related deaths from the same agencies.

---------- Post added August 22nd, 2013 at 08:41 PM ----------

It's not aliens either.

---------- Post added August 22nd, 2013 at 08:48 PM ----------

If you want a community to believe your synopsis it's best that you have empirical evidence to back it up because unrelated hyperbole and strong feelings of what may or may not have caused an incident just doesn't cut the cheese.

 

[DandyDon]

Because I can read the annual statistics from the agencies that collect such information. She didn't address anything other than feelings and one or two reported results. She also "feels" that global results aren't reported which they are. I can quote source material from all reliable and they all say the same thing. Insufficient data. We don't have that problem with any other diving related deaths from the same agencies.

---------- Post added August 22nd, 2013 at 08:41 PM ----------

It's not aliens either.

Who is the "she" you're referencing? Well, it does seem like your mind is not at all open to new information, not matter how well presented. AD explained why the accident reports are lacking, and I gave you air test results that indicate the hidden problem. Since you don't test, you'll never know.

 

[syntaxerrorsix]

Who is the "she" you're referencing? Well, it does seem like your mind is not at all open to new information, not matter how well presented. AD explained why the accident reports are lacking, and I gave you air test results that indicate the hidden problem. Since you don't test, you'll never know.

Whenever you are ready to provide said "new information" let us know. Currently we have none relating to CO being the scourge some folks make it out to be.

---------- Post added August 22nd, 2013 at 08:56 PM ----------

Oh and I don't mean the information like " I heard of a friend who knew a diver."

I mean accurate data first person that DAN and everyone else that ACTUALLY records this sort of info can use.

---------- Post added August 22nd, 2013 at 09:09 PM ----------

And so we are clear... this is from the attached .pdf you dug up from last year.


"The Bottom Line
The good news is that very few divers suffer exposure to lethal doses of CO when diving. But despite the
best efforts of concerned dive centers and the Florida DOH, at least some level of risk of receiving a CO­
laden air fill persists. Perhaps most importantly, for those who perceive the risk as unacceptable, available
testing can put our minds at ease before we slip below the surface."

As stated earlier that number is so close to zero it quickly becomes irrelevant.

Any other links you would care to provide to support my theory?

 

[imasinker]

AGREE 100% all gathered info cut n pasted to a web page.....embarrassing....

 

[Dr. Lecter]

As stated earlier that number is so close to zero it quickly becomes irrelevant.

Things are statistically irrelevant until you become the minor statistical footnote.

Your point isn't that there's no chance of a high CO level in a tank, it's that the odds are very low. Ok, fair enough. I honestly have no idea what the chances of any tank fill having a problematic level of CO in it are, much less here in the US. But I know for sure that those odds are still greater than zero, and that a deep air dive is not where I want to find out whether 5 or 10 or 15ppm CO is really going to kill someone. Thus, I check my air to be sure it's air, and then I check my air for CO, just like I check my deco gasses for being the % they're supposed to be and for CO. It's not expensive, difficult, or time-consuming.

So what's your point, exactly? That CO in a tank is long enough odds you're happy to risk it? That's fine by me. Some people will take air fills past 200' without checking them to be sure they didn't get 32% accidentally. That's fine by me, too...the odds are pretty slim there as well, though you won't catch me doing it. But personal feelings aside... do you have some actual point to share, like you think the odds are so low that nobody should be bothering to test for CO? That CO analyzers are a rip-off? That DandyDon actually owns huge amounts of stock in Analox?

 

[syntaxerrorsix]

Things are statistically irrelevant until you become the minor statistical footnote.

Your point isn't that there's no chance of a high CO level in a tank, it's that the odds are very low. Ok, fair enough. I honestly have no idea what the chances of any tank fill having a problematic level of CO in it are, much less here in the US. But I know for sure that those odds are still greater than zero, and that a deep air dive is not where I want to find out whether 5 or 10 or 15ppm CO is really going to kill someone. Thus, I check my air to be sure it's air, and then I check my air for CO, just like I check my deco gasses for being the % they're supposed to be and for CO. It's not expensive, difficult, or time-consuming.

So what's your point, exactly? That CO in a tank is long enough odds you're happy to risk it? That's fine by me. Some people will take air fills past 200' without checking them to be sure they didn't get 32% accidentally. That's fine by me, too...the odds are pretty slim there as well, though you won't catch me doing it. But personal feelings aside... do you have some actual point to share, like you think the odds are so low that nobody should be bothering to test for CO? That CO analyzers are a rip-off? That DandyDon actually owns huge amounts of stock in Analox?

You can do whatever you like. All I'm stating is there aren't enough facts to support any real concern for CO. There are PLENTY of facts to support just about any other way a diver has died. In light of this I'm going to take a jaded stance when someone tries to tell me that the industry/shop/region/whoever is covering those particular deaths up.