Fatality Cabo San Lucas March 3

[AggieDiver]

One thing to keep in mind if you buy the calibration gas to check your analyzer is that most compressed gas cylinders cannot be transported via airplane unless empty and open. So while it will do some good to calibrate it at home, the change in barometric pressure, temperature, humidity, etc are probably going to result in a skewed value anyway. So when traveling, the "field calibration" of blowing into the intake and seeing if it registers is probably about the best you can really expect. Just understand that the reading is not exact if you didn't calibrate it right before you tested and use the knowledge accordingly. If I were testing and saw a 9, I would be just as concerned as if I saw an 11.

 

[swamp diver]

One thing to keep in mind if you buy the calibration gas to check your analyzer is that most compressed gas cylinders cannot be transported via airplane unless empty and open. So while it will do some good to calibrate it at home, the change in barometric pressure, temperature, humidity, etc are probably going to result in a skewed value anyway. So when traveling, the "field calibration" of blowing into the intake and seeing if it registers is probably about the best you can really expect. Just understand that the reading is not exact if you didn't calibrate it right before you tested and use the knowledge accordingly. If I were testing and saw a 9, I would be just as concerned as if I saw an 11.

Analox sells an aerosol can of "bump gas" (not calibration gas) which one can travel with in the checked baggage the same as you one can travel with a can of pressurized shaving cream in checked baggage. Because the pressure is less than 40 psig, the tank volume is small, and the CO concentration at 10 ppm is no more than dirty urban air, it is approved for passenger flight checked baggage travel. Otherwise as you suggest simply blowing gently into the monitor should produce a reading in the 1 to 3 ppm range if a non-smoker.
EII CO Bump Test Gas: Analox - Looking after the air you breathe.

One only calibrates the unit every 6 to 12 months but should verify the sensor is responding to CO prior to each dive trip. If not responding to an informal bump test using bump gas or breath then one would do a formal calibration. Analox offers these formal calibrations for a fee as do some of the dive shop CO analyzer vendors.

 

[DandyDon]

I think this was touched on a little bit over the previous 69 posts but not enough to satisfy my curiosity. If you are breathing in air that has too much carbon monoxide will you have obvious breathing difficulties? If yes, will those difficulties occur within the first few minutes of the dive? In other words, if you were to stay at a shallow depth for a few minutes would you KNOW to abort the dive? And if carbon monoxide wasn't the cause of this woman's death what other types of air contamination might be responsible for the other divers experiencing difficulty breathing? And is it possible (or HOW is it possible) for the shop that owns the tanks to have done something prior to or after getting the tanks filled, that would have contaminated the air? And finally, is there any sort of analyzer that will test for carbon monoxide AND other contaminants that would be dangerous for us to breathe at depth?

I am not sure about the answers to some of your questions, as well as some of the claims of the divers having difficulty breathing, nor why the family is convinced of CO poisoning as their sources have not been mentioned.

As far as early signs of CO problems, I don't think there are any you can count on. It dulls your thinking and reduces your abilities making it even more dangerous. See Risks of Carbon Monoxide poisoning

One thing to keep in mind if you buy the calibration gas to check your analyzer is that most compressed gas cylinders cannot be transported via airplane unless empty and open. So while it will do some good to calibrate it at home, the change in barometric pressure, temperature, humidity, etc are probably going to result in a skewed value anyway. So when traveling, the "field calibration" of blowing into the intake and seeing if it registers is probably about the best you can really expect. Just understand that the reading is not exact if you didn't calibrate it right before you tested and use the knowledge accordingly. If I were testing and saw a 9, I would be just as concerned as if I saw an 11.

I think the bump gas can that Analox sells is small enough that it can be flown on most airlines, but I didn't get it. With their field calibration knob, I can set it to zero in clean air away from traffic, then blow to make sure it reacts. I would not want to field calibrate say on Melgar street in Cozumel near the docks nor once the boat motor is started. I suppose one could on a very open and moving boat, not one with a cabin that can lead to stationwagon-effect, but I learned the hard way to check air before leaving the dock.

For my Pocket CO I carry for backup, I keep it inside a slider ziplock for almost the entire trip as it can get fouled by humidity and various other fumes. I do wear it on the plane since I have it with me anyway, but for my hotel room I take one of my home CO monitors as all hotels have water heaters even if they do not have room heating.

 

[boulderjohn]

I think this was touched on a little bit over the previous 69 posts but not enough to satisfy my curiosity. If you are breathing in air that has too much carbon monoxide will you have obvious breathing difficulties?

Probably not.

If yes, will those difficulties occur within the first few minutes of the dive? In other words, if you were to stay at a shallow depth for a few minutes would you KNOW to abort the dive?

The problem intensifies at depth because of increasing density--you are inhaling more molecules with each breath the deeper you go. A safe level in shallow water can be fatal at greater depths.

And is it possible (or HOW is it possible) for the shop that owns the tanks to have done something prior to or after getting the tanks filled, that would have contaminated the air?

That could really only happen if the previous fill was contaminated and there was a remnant of that contamination in the tank. The problem with that theory is that if the fill was with good air, than the previous contamination would be significantly diluted by the good air. For the diluted contamination to still be strong enough to cause a problem after being diluted, it would have had to be highly contaminated before, and it would have to have caused a problem in its previous use.

 

[Johnoly]

This is not related to the mentioned accident and I'm going to apologize in advance for this shorter over simplified answer. We really need a better, fully detailed post by a diving doctor who specializes in CO poisoning.

.. If you are breathing in air that has too much carbon monoxide will you have obvious breathing difficulties?

Not neccessarily. And by the time you do recognize that you are having problems breathing and possible CO poisoning, your blood(Hemoglobin) may be so saturated that even putting you on 100% O2 will not lead survival.

....If yes, will those difficulties occur within the first few minutes of the dive? In other words, if you were to stay at a shallow depth for a few minutes would you KNOW to abort the dive?..

It's much more complicated than that. Depth, CO concentration, O2 percentage, workload and so much more factor into if you will have a problem.

In short, blood(hemoglobin) carries your O2 molecules to your tissues. Your hemoglobin has 4 attachment points that can accept either an O2, CO or other molecule. The hemoglobin "likes" the CO molecule 200 times better than an O2 molecule. If both molecules are present, the CO molecule usually wins. Once the hemoglobin accepts just a single CO molecule at one of the attachment points, it changes the hemoglobin and will not allow it to accept an O2 molecule at the other attachment points or even later as the hemoglobin recirculates again. It could take hours for the hemoglobin to release the CO molecule.

So this train of hemoglobins passing through the lungs with a CO molecule already attached and is refusing to be exhaled/released, will just bypass the O2 molecules that your body so desperately needs. If you can't get O2 molecules to your tissues, the body will start shutting down.

If your hemoglobin refuses to release the CO molecule, you can put someone on 100% forced O2 and it may not do any good, maybe not even in a chamber. It just depends how bad the poisoning is.

This is an over simplified explanation and short answer for you. Further questions on this really should be put in the Dive Medicine section for a specialist to answer more completely.

CO is a colorless, odorless gas that you can't tell if its in your tank unless you test your tank. I hate accidents, so I wear my seatbelt every time and I test every tank I dive. Which is why I'm going diving tomorrow with tested tanks.

 

[DMJohn]

I wouldn't worry too much about Cozumel if you can stay close to your diving hotel and not go out at night, get drunk and stagger down some dark street by yourself in San Miguel. That and flashing bucks is asking for it. Stay in groups and get in at night. I wouldn't even think about traveling over on the Mainland. Biggest problem in both places are the corrupt police. Very dangerous to your wallet.

Thanks, not too concerned about Coz...I travel over 100 nights a year and have been in much rougher places. This thread is definitely a good education on CO and the different ways it can be introduced into the tanks. I've always been a stickler when it comes to nitrox testing but I'm adding a CO analyzer to the gear bag for sure. I trust our LDS air (since it is well maintained and monitored, and I fill my own tanks) but traveling when the tanks just magically show up on the boat has always made me wonder. I really like the info I have read on the Analox so I'm going with that one.


I used to work in the automotive industry and have had enough CO exposure to last me for the rest of my life.

 

[swamp diver]

I think this was touched on a little bit over the previous 69 posts but not enough to satisfy my curiosity. If you are breathing in air that has too much carbon monoxide will you have obvious breathing difficulties? If yes, will those difficulties occur within the first few minutes of the dive? In other words, if you were to stay at a shallow depth for a few minutes would you KNOW to abort the dive? And if carbon monoxide wasn't the cause of this woman's death what other types of air contamination might be responsible for the other divers experiencing difficulty breathing? And is it possible (or HOW is it possible) for the shop that owns the tanks to have done something prior to or after getting the tanks filled, that would have contaminated the air? And finally, is there any sort of analyzer that will test for carbon monoxide AND other contaminants that would be dangerous for us to breathe at depth?

Lots of good questions there so we'll try and answer a few.

The symptoms one would experience from CO exposure is going to depend on many factors such as age, smoking status, work load, and most importantly the exposure concentration, depth, and time. Age is a big factor and young healthy divers would tolerate higher CO exposures than an older unfit diver.

At low exposure concentrations likely the first noticeable symptom would be a headache, possibly some nausea, and drop in exercise tolerance. This latter symptom was the complaint the Montreal fire fighters noticed initially when they reported problems with the quality of their breathing air subsequently found to be from CO contamination. As the CO concentration increases further, either directly or effectively by diving deeper, one would start to notice significant shortness of breath, anxiety, chest pain, etc.

If one asks the compressed breathing air laboratories what is the most common contaminant after moisture and CO2 are removed from the list it is carbon monoxide at the top of the list. Second on the list depending on which lab you speak with is non-methane hydrocarbons which are volatile compounds such as xylene, toluene, ethylbenzene, hexane, etc. all compounds which have been found in dive air.
These compounds generally do NOT produce shortness of breath but rather produce narcosis out of proportion to the depth. If one was exposed to only a pure hydrocarbon in general there would be a period of excitation (think of drinking a few beers) followed by a gradual lowering of one's level of consciousness until eventually the regulator would fall out of one's mouth and drowning would ensue due to loss of consciousness. This acute central nervous system toxicity is very different from carbon monoxide with its cardio-respiratory toxicity.

Below is an excellent real life description of a CO poisoning incident where the diver had a significant CO exposure and a hard bottom at 20 feet. Had he gone deeper he likely would have drowned. The tank gas was analyzed and showed high concentrations of CO. The reason his buddy had fewer symptoms and a lower concentration off the same compressor was that his tank still had 1500 psi of clean air in it so the CO from the faulty compressor was diluted more than the photographer whose tank only had 500 psi of air prior to the problematic fill directly off the compressor.
August 2008 Volume 18 Number 8


If you are interested in how a pure hydrocarbon exposure would present initially have a look at these commercial divers who came back to the bell with crude oil smeared on their dry suits. The vapor from this oil gave off benzene, ethyl benzene, toluene, xylene (BTEX), and other non-aromatic hydrocarbons all of which are highly narcotic. One can see the initial state of excitation, but more importantly the severe cognitive impairment (unable to put on full face mask) at concentrations well below where any significant drop in their level of consciousness was detected. These BTEX compounds can be found in compressed breathing air due to compressor and purifier dysfunction.
Diving Bell atmosphere protection with Analox Hyper Gas - YouTube

One can smell the BTEX and hydrocarbon compounds in most cases but the CO remains odorless which is why one must analyze for CO in the compressed breathing air. Always smell your breathing air prior to use, and one in the buddy pair or dive group should own a CO analyzer.

 

[Ayisha]

At low exposure concentrations likely the first noticeable symptom would be a headache, possibly some nausea, and drop in exercise tolerance. This latter symptom was the complaint the Montreal fire fighters noticed initially when they reported problems with the quality of their breathing air subsequently found to be from CO contamination. As the CO concentration increases further, either directly or effectively by diving deeper, one would start to notice significant shortness of breath, anxiety, chest pain, etc.

bold added

That's the first time that I've read about shortness of breath or chest pain associated with CO poisoning. We usually only hear about a headache, nausea and vomitting. Thanks Doc.

 

[swamp diver]

bold added

That's the first time that I've read about shortness of breath or chest pain associated with CO poisoning. We usually only hear about a headache, nausea and vomitting. Thanks Doc.

The diver training magazine incident above is pretty much what one would expect to find with an early CO poisoning underwater. Even though he was breathing a fixed concentration at a fixed depth over time his COHb concentration would have slowly increased until the COHb equilibrium concentration was reached for that exposure concentration. In other words had he spent more time at the fixed depth his symptoms would have increased which is why with any symptoms of shortness of breath or chest pain underwater it is important to get back to the surface and breathe clean ambient air or oxygen which will speed the elimination of CO by the lungs.

There are plenty of medical papers around showing that if one has occult or pre-existing coronary artery disease (CAD) low-level CO exposure can provoke angina (chest pain). Older divers with undiagnosed coronary artery disease swimming against a current may present with new onset of angina should there be low-level CO contamination in the breathing air. This older group of divers, particularly if they have CAD, is the most sensitive to CO contamination and is why the CO specification in the British and our Canadian compressed breathing air standard for air diving has been lowered to 3 ppm in 2011. Lots of divers out there today with stents and previous MIs and many who have yet to be diagnosed CAD.

Unstable angina and exposure to carbon monoxide.
MMS: Error

 

[Dive-aholic]

I think this was touched on a little bit over the previous 69 posts but not enough to satisfy my curiosity. If you are breathing in air that has too much carbon monoxide will you have obvious breathing difficulties? If yes, will those difficulties occur within the first few minutes of the dive? In other words, if you were to stay at a shallow depth for a few minutes would you KNOW to abort the dive? And if carbon monoxide wasn't the cause of this woman's death what other types of air contamination might be responsible for the other divers experiencing difficulty breathing? And is it possible (or HOW is it possible) for the shop that owns the tanks to have done something prior to or after getting the tanks filled, that would have contaminated the air? And finally, is there any sort of analyzer that will test for carbon monoxide AND other contaminants that would be dangerous for us to breathe at depth?

It really depends on the concentration of CO ion the gas. In the incident I was involved in there were no visible signs for 15 minutes, maximum depth was 40', average depth 30'. At about 15 minutes, Brendan suddenly started swimming faster. He swapped regulators, and then passed out.

There are a few possible ways for cylinders to get contaminated - Carbon Monoxide.

There are CO analyzers. Analox has the best one IMO - Analox CO Analyzer. CO is the major concern. If there are other contaminants present, there will also usually be CO present.