Carbon Monoxide in Scuba Tanks: Risks and Protection

Page 2It was recently suggested that the risk was negligible, not enough to warrant divers taking actions - but a member with extensive experience on the subject offered good reason to think the risks are around 3-5%...

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. 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.

Sadly, the situation will not change much until more divers take actions, testing tanks, complaining about small readings, leaving boats after larger readings, and voting with their business as well as their reports here on SB. The portable Analox unit can be acquired at EII CO- Portable Carbon Monoxide Checker for as little as $325 including free shipping in the US, higher internationally and is a breeze to use tank after tank, T90 readings in 30 seconds. Turn the dial to field calibrate, blow in it to register a few digits and confirm it works (everyone’s breath contains a few points of CO), and go. Don’t bother with the bump gas offered.

Continued Page 3

27 Responses

  1. I check my own gas with my CO analyzer, I am paranoid.
  2. Personally it may be considered that equally important<br /> with far higher statistics relative to unbenownst to them <br /> diver incident statistic is to be trained beyond experience<br /> Electronic gadget or not<br /> Let's say one has been present during one thousand fills<br /> I'm really not too sure be they 21 or other that other <br /> than the operator or the odd end user did much checking<br /> An understanding of how a hunky dory fill station should<br /> look and smell may perhaps be a far more legitimate for a<br /> life saving course than implicated fear through information<br /> <br /> <br /> In other words learn your stuff before you go have fun
  3. I still get the sense that many experienced divers (of which I am not one) think that the concern with CO and especially the drive to buy expensive analyzers is an overkill response to a very low likelihood risk. There are lots more commonn ways to get into trouble and the reliance on yet another piece of technology perhaps sends a wrong message that we can be complacent underwater as long as we have bought enough cool stuff. I expect to buy a CO analyzer. But I am still taking the lesson - like from the recent tragedy in Cozumel - that basic buddying skills, using your training, and vigilant self-reliance (not just assuming that your DM will protect you) are required at all times. The toys can be helpful and if you can afford them, why not. But they are not a substitute for the basics. The more experience I get, the more I realize that I have to start being more self-reliant and less reliant on the DM like a newb.
  4. <blockquote><strong>fred3798;6288546 wrote:</strong> I still get the sense that many experienced divers (of which I am not one) think that the concern with CO and especially the drive to buy expensive analyzers is an overkill response to a very low likelihood risk. </blockquote> <br /> One question is whether the old belief from experienced divers that CO is infrequent is erroneous. Previously, instruments to measure CO were rare, expensive and inconvenient. It's only in the last couple of years that most measurements were not made under ideal compressor operating conditions right after the filters were changed. So previous beliefs that there were no problems were based on basically never checking.<br /> <br /> Now keep in mind that problems with CO depend on how much someone gets. So remembering the symptoms of CO, how many of those cases of post-dive tiredness, traveller's flu or even dry coughs might actually have been caused by a non-lethal dose of CO and other contaminants. And although panic attacks and in-water heart attacks are usually triggered by something more obvious like exertion and victims being pushed over the edge, how many of those cases were contributed to by the edges having been moved closer by CO having blocked part of the blood stream's oxygen carrying capacity?<br /> <br /> All of these may or may not be happening. Old 'observations' from the era when it wasn't being realistically or regularly measured aren't good evidence, so need people to get out and measure it. In the mean time, there's already a small amount of circumstantial evidence and anecdote that CO may be contaminating as much as 3-5% of all tanks in concentrations that can be medically significant, mentioned previously in this and other thread. There have also been recent reports in other threads from people who have been using these instruments that they are occasionally finding problems. So problems are happening, but the question is how often.
  5. Is CO a problem? We need the facts. If someone is using an analyzer and finds tanks high in CO please post it here on SB. This will bring attention to that dive operation more than walking way and hopefully influence shops to meet our expectations and prevent a fellow diver form possibly getting a CO hit in the future.<br /> <br /> ML

  6. <blockquote><strong>fred3798;6288546 wrote:</strong> I still get the sense that many experienced divers (of which I am not one) think that the concern with CO and especially the drive to buy expensive analyzers is an overkill response to a very low likelihood risk. There are lots more commonn ways to get into trouble and the reliance on yet another piece of technology perhaps sends a wrong message that we can be complacent underwater as long as we have bought enough cool stuff. I expect to buy a CO analyzer. But I am still taking the lesson - like from the recent tragedy in Cozumel - that basic buddying skills, using your training, and vigilant self-reliance (not just assuming that your DM will protect you) are required at all times. The toys can be helpful and if you can afford them, why not. But they are not a substitute for the basics. The more experience I get, the more I realize that I have to start being more self-reliant and less reliant on the DM like a newb.</blockquote> <br /> However, in this case basic skills may not be enough to save ones life. CO toxicity can sort of sneak up on you, when you least expect it, rendering you unconcious before anyone can realize it. And if your buddy got his air from the same batch of tanks, or from the same faulty or poorly maintained compressor, then he too may be susceptable to that same poisoning. Basic buddy skills serve a diver, any diver greatly at any level, however they can be rendered moot when both you and your buddy are rendered incapitated oir ill at depth. And sometiems, for al lthe skill in the world, a highly trained, astute buddy may not be enough to help if you go unconscious at depth, loose your reg, and asphyxiate on water. Of course, the incident pit is never that forgiving. A more liklely scenario, is that you fall unconscious, your reg falls away, you draw in water while unconscious. Your buddy finally notices after taking pictures of a moray eel, panics, and rushes you to the surface, blowing past a safety stop or any deco obligation the two of you might have. So now in this worst case scenario, they still have to attempt reviving you, clearing your airways, hopefully getting you on O2, hopefully getting you to medical aid as soon as humanly possible, then getting you and your buddy into a chamber. What could have avoided a near death experience, two bent divers, and a small fortune in hospital costs? a $300 "toy." Most toys are not that effective.<br /> <br /> Suggesting that CO analyzers can be viewed as some sort of a nicky-neat toy, takes away from the true purpose of the devices. You should not look at a CO tester and think toy, you should think required tool for my trade or even life support testing. Just as you look at (hopefully) your BC or regulators being life support. If we instill this sort of thinking in new divers, then perhaps they will not view their equipment as toys or as just gear. What you are posting about is a pervasive attitude, amongst recreational divers who look at dive gear as though it is no more than snorkel gear. I think the watering down of a lot of certification programs are a direct cause of this sort of attitude. Just as a Nitrox diver would not dream(Hopefully) of not testing their Oxy content of their tank, we should not think of diving without testing the quality of our air/gas. In this instance, I would much rather decome dependant on this tool, which just may save my life, and is a far cry from becoming dependant on a dive computer for instance. Both devices give me information, however one calculates information I should be able to calculate on my own, whereas the CO checker gives me information I cannot gather otherwise.
  7. How would this work when diving with Nitrox, are you able to test for both?<span style="color: Silver;"><br /> <br /> <span style="font-size: 11px;">---------- Post added April 9th, 2012 at 02:06 PM ----------</span><br /> <br /> </span>How would this work when diving with nitrox, would the co change the mix of nitox?

  8. I imagine the sensor will still pick up the CO since its designed to sense a different molecule. So for Nitrox, all you do is two separate tests, one for Oxy content, the other for CO content.
  9. My husband and I are fairly new divers (less than 100 dives each). We both took the PADI open water, and Advanced, and have done nitrox training. Until recently I did not even know that CO poisoning was a potential issue with diving! I don't recall seeing that in the books, or dvds, or hearing it from a real live person. Maybe I missed it? Anyway, thank you for all the discussion, and opening my eyes to this possibility.<br /> <br /> I think it makes a lot of sense to get a tester and check the tanks before you dive - $300 is not a lot to spend if it could save you & your buddy's life! Any recommendations on a specific tester to purchase? Thanks for the great discussion! Headed to bed a much more educated diver!
  10. THe Analox website has an explanation and a user manual for the CO tester- EII.<br /> <br /> <a href="http://www.analox.net/proddetail.php?productid=91&ref=11">EII CO Carbon Monoxide Analyzer: Analox - Looking after the air you breathe.</a><br /> <br /> The manual states that you need both CO and O2 analyzers. <br /> <br /> In reply to your question whether CO changes the mix of nitrox: A toxic amount of CO would still be (same) toxic no matter how much O2 is in the mix. <br /> <br /> I don't know if you are suggesting that there is an inference from measuring O2 content to estimating CO content, but if so, that inference appears illogical. It would be dangerous to guess in that manner. IMHO.<br /> <br /> <br /> Dive Safe<br /> <br /> <br /> <br /> <blockquote><strong>Incognegro;6298505 wrote:</strong> How would this work when diving with Nitrox, are you able to test for both?<span style="color: silver;"><br /> <br /> <span style="font-size: 11px;">---------- Post added April 9th, 2012 at 02:06 PM ----------</span><br /> <br /> </span>How would this work when diving with nitrox, would the co change the mix of nitox?</blockquote><span style="color: silver;"><br /> <br /> <span style="font-size: 11px;">---------- Post added April 12th, 2012 at 09:19 AM ----------</span><br /> <br /> </span>
  11. There seems to be a line of thinking that people can view a fill station and "know" whether they are safe...or whether their buddies are "doing a good job". Personally I think that is silly, know of divers who have been injured and one that died from co.<br /> <br /> I test every single tank my wife and I breathe for o2 content and co, but then again I wear my seatbelt, monitor my blood pressure and exercise in order to keep diving as long as I can. Others can do whatever they'd like, not my problem.<br /> We've been testing co for over 2 years now and the current line of testers are really great, cost around 2-300 dollars and well worth the money in my opinion.
  12. <blockquote><strong>runnerchic71;6300628 wrote:</strong> <br /> ...<br /> Until recently I did not even know that CO poisoning was a potential issue with diving! I don't recall seeing that in the books, or dvds, or hearing it from a real live person. Maybe I missed it? Anyway, thank you for all the discussion, and opening my eyes to this possibility.<br /> ...</blockquote> Contaminated air should have been covered in your OW course. IIRC it dont go into very much detail, but it does mention making sure your air comes from a reliable source and to not breathe air that smell or taste funny. Cant recall it going into specifics of CO though other than possibly making sure the fill station dont have exhaust going out from the compressor/nearby vehicles near the air intake.
  13. I think random exhaust could be the unknown scary issue. I really wonder, though, how much a car or boat exhaust can contaminate an air fililng station nearby - really have no idea. But, I remember sitting on a balcony of a hotel in Key Largo a few years back watching tanks get filled on the dock while a fishing boat pulled up coughing blue smoke and tied up right next to the fill shed. I certainly cringed, but even being a diver I didn't really know or think about CO Analyzers until DandyDon got me on board his mission :cool2:

  14. <blockquote><strong>oerentals;6303572 wrote:</strong> I think random exhaust could be the unknown scary issue. I really wonder, though, how much a car or boat exhaust can contaminate an air fililng station nearby - really have no idea. But, I remember sitting on a balcony of a hotel in Key Largo a few years back watching tanks get filled on the dock while a fishing boat pulled up coughing blue smoke and tied up right next to the fill shed. I certainly cringed, but even being a diver I didn't really know or think about CO Analyzers until DandyDon got me on board his mission :cool2:</blockquote> Exhausts can be a source, more so with pluming around compressors and station-wagon effects on liveaboards. However, an electric compressor with clean intake can still produce CO internally when it burns its own lubricating oil during busy periods when the machine heats up - especially in tropical climates. We now have the ability to easily test tank air, a recent innovation really. Testing dozens of tanks and getting nothing can be boring but reassuring, but the first time you see digits is eye opening. :shocked2: If you test a hundred tanks finding nothing, or drive 100,000 miles without a wreck - great, but knowing what you are breathing at depth and wearing seatbelts are still good ideas.
  15. <blockquote><strong>DandyDon;6304209 wrote:</strong> If you test a hundred tanks finding nothing, or drive 100,000 miles without a wreck - great, but knowing what you are breathing at depth and wearing seatbelts are still good ideas.</blockquote> <br /> It is even worse than that <br /> You can drive your car without a seat belt & until you crash it won't be an issue, & you may have an airbag or 3 to save you.<br /> <br /> but high C0 & depth = serious problem...<br /> <br /> We had C0 in the 3rd cylinder we ever tested<br /> <br /> This had been filled by a dive shop from their van.. - Diesel compressor.<br /> <br /> Now every cylinder gets tested - before we fill & after.
  16. an option for some is to purchase a CO tester as a group, assuming you either go on the same vacations, or at lease at different times.

  17. <blockquote><strong>nimoh;6304323 wrote:</strong> an option for some is to purchase a CO tester as a group, assuming you either go on the same vacations, or at lease at different times.</blockquote> You could. Since you can now rent one of a week long trip for $35 +shipping, that sounds easiest.
  18. <blockquote><strong>DandyDon;6304419 wrote:</strong> You could. Since you can now rent one of a week long trip for $35 +shipping, that sounds easiest.</blockquote> <br /> thanks, did not know about the renting option. Probably a good option for anyone that goes on one trip per year, and trusts their local fill station.

  19. <blockquote><strong>nimoh;6304441 wrote:</strong> thanks, did not know about the renting option. Probably a good option for anyone that goes on one trip per year, and trusts their local fill station.</blockquote> It's a new option that developed after I wrote the article. See my current Sig for a link, or his...<br /> <blockquote><strong>oerentals;6303572 wrote:</strong> I think random exhaust could be the unknown scary issue. I really wonder, though, how much a car or boat exhaust can contaminate an air fililng station nearby - really have no idea. But, I remember sitting on a balcony of a hotel in Key Largo a few years back watching tanks get filled on the dock while a fishing boat pulled up coughing blue smoke and tied up right next to the fill shed. I certainly cringed, but even being a diver I didn't really know or think about CO Analyzers until DandyDon got me on board his mission :cool2:</blockquote>
  20. <blockquote><strong>DandyDon;6304448 wrote:</strong> It's a new option that developed after I wrote the article. See my current Sig for a link, or his...</blockquote> <br /> In the mid 70's when I started "bad air" was taught as risk to be considered. NASDS of course said use only a NASDS shop to do your fill. In real life if a diver got a bad tank the word spread and said shop was black balled by divers. I am not at all sure how real it was but you would hear go here not there as the guy had done bad air fills. Some of these rumors I bet were started by the competition. <br /> <br /> That said I asked when I did a re-cert 2 years ago while this is not talked about, the DI said it is a non issue today and PADI does not make mention of it.

  21. <blockquote><strong>Johnmpcny;6319358 wrote:</strong> In the mid 70's when I started "bad air" was taught as risk to be considered. NASDS of course said use only a NASDS shop to do your fill. In real life if a diver got a bad tank the word spread and said shop was black balled by divers. I am not at all sure how real it was but you would hear go here not there as the guy had done bad air fills. Some of these rumors I bet were started by the competition. <br /> <br /> That said I asked when I did a re-cert 2 years ago while this is not talked about, the DI said it is a non issue today and PADI does not make mention of it.</blockquote> We didn't even have home smoke alarms in the 70s, did we? Sad that some homes today still don't, or lack a $1 battery. Home CO alarms start at less than $20, but many homes and I think most businesses lack those. It snowed in the northeast recently, and this broke about that time: <strong><a href="http://www.gazette.net/article/20120425/NEWS/704259403/1124/five-killed-in-oxon-hill-carbon-monoxide-leak-identified&template=gazette">Gazette.Net: Five killed in Oxon Hill carbon monoxide leak identified</a></strong><br /> <br /> My daughter's school only has one CO monitor - the one I gave her for her classroom, and I got them one for each bedroom even tho they have an all-electric home - aside from the garage near my grandkids and the fireplace on the other side of the house. I take one for each hotel room on trips, and they just smile. I doubt they take one on trips I don't join, as much as I ask, but they didn't grow up heating with space heaters before sensor technology. I keep nagging gently and hope...<br /> <br /> Tank testing technology is so much more precise, but now affordable. The more divers test, the more providers will try to prevent problems, and hopefully close calls will be very rare - losses more so. It's worth the effort and expense to know for sure, I think - and I think all the divers on the boat where we found 17 ppm agree now. :eyebrow:<br /> <br /> I saw a recent post on another board where one diver in a group had a CO tester, used it even tho the others didn't seem to care, and found 10 ppm. They drained and vized, finding significant oil deposits. 10 ppm isn't all that much, but if that gets thru - what else...?? :eek:
  22. Let me Start off by saying this is the first forum i have ever entered, Secondly I would Like everyone no here who I am, I am the Husband Of the recently Deceased woman Killed In Cabo San Lucas On March 3rd of this year. This incident was, I have to say at this point in time (allegedly) by Carbon Monoxide in her tank. We have just had a ceremony here in the Bahamas for her. While i was here, i put my new CO detector to use, I tested over 30 tanks i detected ranges from 1-6 ppm. Wikipedia states that death will occur at 3,600 ppm within 30min. So my question is, does anyone know the formula or calculations for relative surface tests to each level of depth? My wife was only in the water for a total of 10min 26sec. My CO tester has an alarm for 10ppm, but that must translate into a much higher level at depth.<br /> <br /> On a second note, I have to agree, that CO testers should be enforced at all dive shops. the reason, well i had a conversation with a dive shop owner and his answer was "I am away from the elements, and i use an electric compressor". well here is my answer to that, CO levels do not have to be introduced once to affect a diver, but repetitive refills some times with low levels building up can result to a fatal dive, so if a fill station is filling someone else's tank and thy use other locations to fill as well, Than TEST THE TANK!! to me it just makes sense! seems we pay more attention to our air censor in our car than the air that we count on for life!<br /> <br /> Thanks for any help provided.

  23. Hi Colin. I am very sorry for your loss. Your wife's accident was discussed with a lot of speculation, debate, and unanswered questions on a thread in our Accidents forum. See <strong><a href="https://www.scubaboard.com/forums/accidents-incidents/413185-fatality-cabo-san-lucas-march-3-a.html">https://www.scubaboard.com/forums/accidents-incidents/413185-fatality-cabo-san-lucas-march-3-a.html</a></strong><br /> <br /> I am really not the expert to answer some questions, but yes - CO toxicity increases with partial pressure at depth, but there is a lot more to it than that....<br /> <br /> <ul> <li>As the diver ascends, the partial pressure of Oxygen that was offsetting the CO in part decreases rapidly, while that of CO very slowly.</li> <li>Additionally, if CO is allowed to enter the tank - one has to wonder what other contaminants might be in it as well.</li> <li>And more - not all of it well understood, hence the low amounts legally allowed in countries that do regulate.</li> </ul> <br /> I really do not think that CO leaves a residue in a tank from repeated exposure, but an electric compressor can still produce toxic tank fills from other fumes that might be intaken and/or by partially burning its own lubricating oil as the machine heats up. You never know about the next tank without testing. I do hope you can obtain some dependable answers on your wife's tank tests at least.<br /> <br /> I think these limits for CO exposure at one atmosphere are more dependable than those given by Wiki: <strong><a href="http://www.detectcarbonmonoxide.com/risks.html">Risks of Carbon Monoxide poisoning</a></strong>
  24. Excellent article DandyDon! I own an Analox CO tester thanks to your drive to get the word out!

  25. <blockquote><strong>ktomlinson;6322313 wrote:</strong> Excellent article DandyDon! I own an Analox CO tester thanks to your drive to get the word out!</blockquote> Hope you will report any positive readings from your travels. Always getting zeros is boring I know, but so reassuring.

  26. I prefer for my pre-dive testings to stay boring, as the alternative is more excitement than I prefer.
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