Update: Now I Have a Personal Carbon Monoxide Monitor/Tester

[Doubler]

Thanks Dan, Now along with my VHF radio with GPS and NITROX tester I can add the CO tester to my away kit. I am one that firmly believes in safety first and that your best dive buddy must be yourself first. Eliminating issues before you get in the water for yourself and your team is just as important as keeping track of each other in the water.

Jim

 

[LeadTurn_SD]

Thanks for posting this DandyDon!

CO contamination is something I've tried not to dwell on too much, since I was not aware of an easy way to test for it... I'm not concerned about the local dive shops in Hawaii (I know and trust the people I get airfills from), but if/when I do travel to faraway lands, it would be a great device to provide some peace of mind and increased safety.

What would be nice (but maybe not possible with current technology?) would be a CO tester that could take a small sample directly from a LP hose, then give a readout... maybe wishfull thinking but it would be easier.

Safe Diving!

 

[hdtran]

Ditto my thanks to DandyDon for some great research.

Pteranodon, I think that your reasoning may be incomplete. Though you may have a 10ppm concentration at 4 atm (120 fsw, more or less), you'll have the equivalent of 4x the amount of moles. Even if the CO<-->Hemoglobin binding is reversible, because of the greater affinity of CO relative to O2, you may wind up with less O2 in the bloodstream if you have more CO molecules available. (Of course, I'm no physical chemist, so I may not have my math right...).

Regardless, we are all in agreement that CO testing is important & necessary!

DandyDon,

I think you take a forward-thinking approach here and raise an issue that hardly gets any attention usually. I think the discussion about the danger from CO poisoning is needed and want to thank you for bringing this up. However, I am concerned about your reasoning about concentration at depth. I do not believe you can equal a CO concentration of 10 ppm at 5 atm to 50 ppm. Keep in mind that unlike partial pressure, the concentration of a gas does not change with depth. If my tank is contaminated with 10 ppm of CO, it doesn't matter what partial pressure I am breathing the gas at. I will always expose myself to 10ppm. Yes, I may breathe 5 times the amount of gas at 5 atm compared to 1 atm, but in relation to all the other gases in the mix, CO will still remain at 10 ppm. As you know, the toxicity of CO results from its competition with oxygen for binding sites on the hemoglobin molecule. This process is reversible and is directly proportional to the concentration of gases present. Hemoglobin has a much higher affinity for CO than for oxygen, which accounts for its toxicity. However, since the process is reversible, an increase of oxygen concentration relative to the concentration of CO will result in the oxygen competing with the CO molecules, allowing fewer of them to bind to hemoglobin. This is why CO intoxication, if detected early, can relatively easily be reversed by administration of 100 percent oxygen. The oxygen molecules "flush" the CO molecules out. Since the relative amounts of gas molecules in your tank remain the same, and the toxicity mechanism is dependent on molecule concentrations, partial pressure has no effect. Therefore, I doubt that it is legitimate to translate higher partial pressures into higher concentrations.

That said, I still think this topic merits more attention and your suggestion of testing tanks for CO is a step in the right direction.

 

[DandyDon]

Ditto my thanks to DandyDon for some great research.

Pteranodon, I think that your reasoning may be incomplete. Though you may have a 10ppm concentration at 4 atm (120 fsw, more or less), you'll have the equivalent of 4x the amount of moles. Even if the CO<-->Hemoglobin binding is reversible, because of the greater affinity of CO relative to O2, you may wind up with less O2 in the bloodstream if you have more CO molecules available. (Of course, I'm no physical chemist, so I may not have my math right...).

Regardless, we are all in agreement that CO testing is important & necessary!

I didn't want to get off on Pteranodon's post at the time, in part because I couldn't remember the details of discussions we've had on that in other threads nor where they were. In general...

• We know that Nitrogen loading increases with depth, so I think it's safe to say that CO loading would in a similar way;
• The maximum CO allowed for scuba air is 10 ppm, 2 ppm for Oxygen safe air I think, but simply having faith that the operator probly maintains and operates the compressor well and fills the tanks safely is a bit much to ask when a fail-safe can be had for less than $150;
• CO deaths are rare that we know of, injuries also rare that we know of, but they do happen, and they're one of the worst ways to ruin a dive vacation to say the least.

We study, train, and drill on all our other pieces of safety equipment but is the compressor not the most important piece? How often do we even look at the source for our air? In many cases we cannot, but if you can inspect it - ensuring that it is clean, well ventilated, and has one of these hooked up to it...

Analox Sport Diving Analyser​

Then that will be somewhat reassuring.

Seeing my own monitor read safely in a plastic bag of air from the exact tank I'll be diving will be even more reassuring.

I'm sorry that interest here on SB is doesn't seem any greater. No one is enforcing rules, not Padi, not tropical governments, no one - and the only way we can identify how many "vacation flu" case were really CO close calls is with this electronic gadget or similar is more common use.

 

[InTheDrink]

I notice that the timeframe in which the divers in the Maldives had acute symptoms was within less than 30 mins IIRC, and also that max depth was < 30m, therefore 4ATA's max. From the symptoms/ppm table above, the contaminated bottle that Roman used would have had greater than 6400ppm at 4 ATAs or 1600ppm at 1 ATA. Of course, individual reactions are different but it sounds like the concentrations were major.

Having said that, the other casualties were tested in the region of approx. 80-100 ppm, and at 4 ATA, say 400 ppm. The chart above says life threatening in 2-3 hours. For 800ppm it says unconciousness in 1 hour, which sounds more like the actual symptoms of the casualties.

So not that one would ever dive intentionally with these concentrations but it might be that the table above is not conservative enough. Either that or the measurements of the other casualities wasn't correct.

 

[hdtran]

The Maldives accidents with one death come to mind, but as DAN says, we don't know how many happen really.

Compressors should have inline monitors with auto shut-offs, and Padi requires quarterly testing by accredited laboratories, but the latter is not enforce and seldom complied with - who knows about the monitors. How many divers ask about such, ask to inspect the compressor...?

Here is what a test analysis looks like. http://www.fantasyislandresort.com/buceo/507931.pdf I wonder if they have tested since...?

If you look at the bottom of that PDF, it gives an accreditation logo. If you further research the accreditation logo, you see that the company which did the gas testing (Trace Analytics) has been examined by external auditors, and according to the external auditors, is found in compliance with ISO standards for calibration laboratories. Putting on my work hat (which is in no way nearly as nice as DandyDon's hat, unfortunately ), that gives me confidence that T.A. is a company with quality procedures, processes, etc. (Of course, putting on my work hat again, I'd rather see inline testing of the air, rather than spot samples, but spot samples is better than nothing...)

 

[bubba105]

DandyDon,

I think you take a forward-thinking approach here and raise an issue that hardly gets any attention usually. I think the discussion about the danger from CO poisoning is needed and want to thank you for bringing this up. However, I am concerned about your reasoning about concentration at depth. I do not believe you can equal a CO concentration of 10 ppm at 5 atm to 50 ppm. Keep in mind that unlike partial pressure, the concentration of a gas does not change with depth. If my tank is contaminated with 10 ppm of CO, it doesn't matter what partial pressure I am breathing the gas at. I will always expose myself to 10ppm. Yes, I may breathe 5 times the amount of gas at 5 atm compared to 1 atm, but in relation to all the other gases in the mix, CO will still remain at 10 ppm. As you know, the toxicity of CO results from its competition with oxygen for binding sites on the hemoglobin molecule. This process is reversible and is directly proportional to the concentration of gases present. Hemoglobin has a much higher affinity for CO than for oxygen, which accounts for its toxicity. However, since the process is reversible, an increase of oxygen concentration relative to the concentration of CO will result in the oxygen competing with the CO molecules, allowing fewer of them to bind to hemoglobin. This is why CO intoxication, if detected early, can relatively easily be reversed by administration of 100 percent oxygen. The oxygen molecules "flush" the CO molecules out. Since the relative amounts of gas molecules in your tank remain the same, and the toxicity mechanism is dependent on molecule concentrations, partial pressure has no effect. Therefore, I doubt that it is legitimate to translate higher partial pressures into higher concentrations.

That said, I still think this topic merits more attention and your suggestion of testing tanks for CO is a step in the right direction.

Swamp Diver could explain this better than me.

With CO being able to attach to hemoglobin at least 200 times (240 seems to be standard) more readily than O2, those 50 ppm you referenced could get dangerous, especially when doing multiple dives. The problem is the ppm CO you breathe that increased partial pressure provides at depth. You are ingesting 50 ppm, which attach to your hemoglobin much more readily than O2. At depth, more O2 is available due to the increased pressure, allowing O2 delivery, however, CO molecules attach over 200 times more readily, so when you ascend & pressure drops, with increased COHb levels, O2 attachment is inhibited. This, I believe, is what happened in the Baani Adventure tragedy. Hope this make sense.

Don, I'll be waiting for the test results.​

Scuba Diver Info - Diving physiology (nice reference page)
Carbon Monoxide Toxicity

[FONT=arial, verdana]Carbon monoxide is an odorless, tasteless gas coming from the combustion of organic matter. It combines with blood, hemoglobin really, much more easily than oxygen, some 200 times more readily in fact. It also won't easily let go of the hemoglobin and that means the blood can carry less oxygen. Carbon monoxide poisoning can happen if a faulty or poorly maintained air compressor adds carbon monoxide into the tank or if it sucks in already contaminated air.


At depth, while the partial pressure of carbon monoxide remains the same, the diver inhales many more carbon monoxide molecules, enough for poisoning symptons such as headaches, confusion, tunnel vision and worse. Divers may pass out because there is no longer enough oxygen. Signs of carbon monoxide poisoning are flushed lips and cheeks. First aid treatment is pure oxygen and fresh air. In serious cases recompression in a chamber with 100% oxygen may bee necessary to reduce, or eliminate, longterm damage.
Smokers already inhale carbon monoxide and are therefore at greater risk for hypoxicity (being low on oxygen).

[/FONT]

 

[swamp diver]

DandyDon,

I think you take a forward-thinking approach here and raise an issue that hardly gets any attention usually. I think the discussion about the danger from CO poisoning is needed and want to thank you for bringing this up. However, I am concerned about your reasoning about concentration at depth. I do not believe you can equal a CO concentration of 10 ppm at 5 atm to 50 ppm. Keep in mind that unlike partial pressure, the concentration of a gas does not change with depth. If my tank is contaminated with 10 ppm of CO, it doesn't matter what partial pressure I am breathing the gas at. I will always expose myself to 10ppm. Yes, I may breathe 5 times the amount of gas at 5 atm compared to 1 atm, but in relation to all the other gases in the mix, CO will still remain at 10 ppm. As you know, the toxicity of CO results from its competition with oxygen for binding sites on the hemoglobin molecule. This process is reversible and is directly proportional to the concentration of gases present. Hemoglobin has a much higher affinity for CO than for oxygen, which accounts for its toxicity. However, since the process is reversible, an increase of oxygen concentration relative to the concentration of CO will result in the oxygen competing with the CO molecules, allowing fewer of them to bind to hemoglobin. This is why CO intoxication, if detected early, can relatively easily be reversed by administration of 100 percent oxygen. The oxygen molecules "flush" the CO molecules out. Since the relative amounts of gas molecules in your tank remain the same, and the toxicity mechanism is dependent on molecule concentrations, partial pressure has no effect. Therefore, I doubt that it is legitimate to translate higher partial pressures into higher concentrations.

That said, I still think this topic merits more attention and your suggestion of testing tanks for CO is a step in the right direction.

Pteranodon I am not sure I follow your logic here as CO being a gaseous contaminant in the breathing air follows the same partial pressure rules as any other individual component in the gas mixture (i.e O2, N2, CO, CO2, CH4, etc.)

If there is 10 ppm CO measured at 1 atmosphere in the lab or with a hand held detector the surface effective concentration at 5 ATA will be 50 ppm and the clinical effects at this depth will be similar to a person sitting in a chair on surface exposed to 50 ppm. In reality these clinical effects will be enhanced at depth due to exertion, increased CO2 due to equipment dead space, etc.

In terms of the physiology of CO poisoning it is now understand that the toxicological effects are not just from the binding of CO to hemoglobin to create a chemical anemia, but in addition a significant proportion of the effects are a direct effect of CO on the energy-producing enzyme chains in the cell's mitochondria. These effects are not easily reversed with oxygen which is the topic of much current research.

Here is a good summary article on CO in Diving by Gavin Anthony published in May 2007.
http://www.analox.net/site/content_pdfs/CarbonMonoxideInDiving.pdf

Of interest is the new British Health and Safety Executive Diving Information Sheet which was published this week. It applies to air diving to 50 metres. Of note is the maximum recommended CO exposure is 3 ppm across the entire dive population. Also the recommendation to install an inline CO detector on the compressor and to have a catalytic bed in the purifier.
http://www.hse.gov.uk/pubns/dvis9.pdf

Recall a young fit non-smoking Navy Seal can tolerate a higher exposure level than an older, obese, unfit, smoker. The levels are set for the most sensitive person in the exposure group.

Don thanks for posting the new CO monitor.

 

[DandyDon]

... that gives me confidence that T.A. is a company with quality procedures, processes, etc. (Of course, putting on my work hat again, I'd rather see inline testing of the air, rather than spot samples, but spot samples is better than nothing...)

TY. I think that TA is the primary tank air analyzer for Fire Departments and Scuba Operators in the US and much of the rest of the world.

Don, I'll be waiting for the test results.

I'll give feedback as I have it from my usage in the field, but I think I am already covered the need and the solution pretty well...

• The risk does exist;
• The extent is greatly unrecognized and cannot be seen until someone dies or tests are done;
• No one else seems to be doing anything much at the industry level - leaving it to the traveling diver to protect his/her own life; and
• A reasonable solution is less than $150 delivered in the US, $40 a year to calibrate, $80 for complete annual services that would also include sensor replacement if needed.

There are other choices in portable CO monitor, but very few and they all cost more. This is but half the cost of my Nitrox analyzer that I felt the need to own in case the dive Operators didn't have a brand I knew and trust - but now they seem to have the same brand I bought. Anyway, I wouldn't dive a Nitrox tank without checking the mix on a monitor I trust, and now I won't dive any tank without checking for this greater risk.

Don thanks for posting the new CO monitor.

Thanks for posting from you obviously educated and experience knowledge.

 

[sambolino44]

In Belize I wondered about the condition of some of the compressors. When I asked about it, the dive masters (who, despite living in a developing country are neither stupid nor uneducated) told me that their compressors regularly checked by PADI. Not only that, but the dive masters themselves, who use those those compressors daily, have a very good incentive to ensure they are maintained properly. In other words, in many cases the guy who maintains the compressor is also the guy who breathes the most air from it.

Having said that, judging from the outward appearance of some of these compressors, anyone would question the air quality.

I wonder:

1. What does DAN say about this?

2. How come there isn't a purpose-built SCUBA tank CO detector? Sometimes the trash bag that I always carry around with me gets a hole in it.