Do you trust your gas supplier?

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Genesis

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I know that's a somewhat-rhetorical question, since we must all to some degree.

But seriously, gas testing is only done every three months. While oil has a "taste", and so you have a personal "alarm", CO, as you probably know, is completely silent - and deadly, especially at depth.

Ever have a headache post-dive? It might have been CO2 retention. It also might have been low-level CO poisoning.

Many folks and places use the "eyeball" CO detectors. Those typcially won't change color until 100ppm of CO or more is reached. The problem is that under pressure, the PCO becomes too high - 100ppm is really 400ppm of equivalent at 99' (4 ATM), which is enough to get you in serious trouble and contribute to an accident, and will definitely make you feel like cr@p for hours with a really nice headache.

Most "residential" CO alarms don't do much for you either, since the UL, in its "inifinite wisdom", decided that alarming at <70ppm was causing too many "false alarms" and thus forced manufacturers to "detune" their devices.

But what if you could test for this potentially deadly problem reasonably cheaply, accurately, and as a bonus, you had a detector that was useful in your house or boat when you're NOT diving?

Look here:
http://www.avweb.com/news/aeromed/186016-1.html#coex

There is a link at the bottom to a company that sells these (this above link is a review) which goes here:

http://www.aeromedix.com/index.php?_siteid=aeromedix&action=sku&sku=coex

I have no interest in this company or its products (financial) but I recognize a good thing when I see it. I own a couple of these - one of the older ones that were previously used by the aviation folks (no longer sold, used to be made in Canada) on my boat, and one of these here at the house that I use for confirmation of "good" gas once in a while on my own fill station.

Since its battery operated you can shove it in a bag along with a large ziplock and use it for field tests. Just blow a bag's worth of gas from your tank in there with the unit and close it up for a couple of minutes. If it doesn't read "0", better find out why! :)

If you dive where you are forced to buy fills from folks you don't know REAL well this is cheap insurance. CO poisoning doesn't happen often, but it only has to happen to you once!
 
I have been using one of the CO Experts detectors and only have great things to say about the device.

As for gas testing Genesis you are very lucky to be living in the state of Florida as you have government mandated quarterly testing of fill stations. Up here in Ontario one is lucky to get biannual testing but last summer after visiting over twenty fill stations personally about forty percent were not testing at all. There is no compliance monitoring by the government or training agencies and so shops get away with this negligent behaviour because they know they can. We are working on changing this but in the meantime one needs to be 'air aware' and the one gas that can kill or make you quite sick is CO. No smell or taste test can tell you if it is there. Hence the CO detector is a perfect device for real time field testing of tanks.

The argument most people will try and use against routine use of these is we don't have a problem with CO poisoning as divers are not dropping dead of CO poisoning. If one looks at the DAN data though there is a large category simply listed as drowning (29%) and complications of near drowning (35%). Any one of those deaths plus the 10% cardiac category could have involved CO poisoning. If one doesn't check the COHb level upon death one never knows if the problem existed and the problem remains under-reported. This may be the case with CO in diving fatalites. Dr. Caruso, a pathologist with the US Navy who reviews DAN data stated in an abstract from UHM 1998:

Results: Of the 451 diving fatalities, COHb levels were known to have been measured in 67 (15%) cases.

Conclusions: ",.....Postmortem toxicology to measure the COHb level, however, is seldom performed in fatal diving mishaps. It is possible that some diving fatalities associated with CO toxicity are being missed. With an increasing number of divers mixing their own breathing gas, CO poisoning may become a more significant problem. Routine toxicology, including a COHb level, should be performed for most diving fatalities. This is especially true when the mishap is unwitnessed, or when there is any possibility that toxic substances may have impaired the diver's performance in the water."

In many jurisdictions there is very sporadic testing of fill station air and certainly not at the quarterly frequency as suggested by PADI and NAUI. We have 65% of fatalities listed as drowning or near drowning and yet only 15% have a COHb level done. One does not know therefore the extent of the problem.

So how does a diver protect himself from potentially bad air? Remain 'air aware' and always ask for an up to date air analysis ideally done within the last three months by an accredited lab. If your shop doesn't have one I would start looking for another fill station. Out in the field the smell and taste test is good for oil detection but won't help with CO contamination. Only a low reading detector like the one above will ensure CO free air if you are concerned in this regard. These detectors are great while traveling to places where you know the fill station's air has never been tested and never will be.
 
IMHO, a COMMERCIAL fill station should be sampling their air with one of these devices DAILY, and be posting the log sheet on the wall next to the fillstation.

Why? Because things break. Three months is a long time.

Taste will, as you noted, detect oil contamination. But it will not detect CO, and CO will kill you very dead, with the effects being more pronounced the deeper you dive.

Is it too much to ask that someone who SELLS gas check it EVERY DAY for CO content? Is it too much to ask when a device that will give you an accurate reading can be had for one hundred dollars?

These shops will maintain an O2 meter for Nitrox fills, but they don't buy one of these? Why not? All it takes is a car running where the exhaust can be inducted into the compressor...

I don't fill for anyone other than myself, but I test my own gas from time to time, most certainly more often than on three-month intervals.

I've yet to see a shop that has as much concern for my health and the purity of my breathing gas as I do. That is just one of many reasons that I do my own fills.
 
While not diving related CO poisonings, this news article illustrates how quickly and quietly CO can kill. It would be quite easy to see how a diving fatality in a healthy person could easily be written up simply as a 'drowning' if CO was not suspected and a COHb level not done.
Car CO poisonings
 
A suggestion on another thread on this topic was to teach in BOW that students should always ask to see an up to date air analysis and if the fill station doesn't have one to look for another fill station. This is not part of either the PADI or NAUI basic open water curriculum and yet would likely root out most of the delinquent fill stations when it comes to testing. It would be hard to teach the quarterly air testing requirement as part of the OW course, but not be following this policy at the instructor's fill station.

PADI states that all its operators are to test quarterly in North America and yet no mention of this to the students. What better way to enfore compliance in this regard than to have thousands of students asking to see their shops most recent air analysis. Unfortunately PADI would then have to actually do something with all the shops not testing quarterly and this is likely why we have not seen such a policy instituted.

Testing quarterly to CGA Grade E is likely as 'good as it gets' down there, but I think your idea of daily CO sampling is an excellent one and not too much to ask for. Funny how the percentage O2 in a tank is double and triple checked, but CO a likely uncommon contaminant but very lethal is rarely checked for.
 
pufferfish:
A suggestion on another thread on this topic was to teach in BOW that students should always ask to see an up to date air analysis and if the fill station doesn't have one to look for another fill station. .....

Testing quarterly to CGA Grade E is likely as 'good as it gets' down there, but I think your idea of daily CO sampling is an excellent one and not too much to ask for. Funny how the percentage O2 in a tank is double and triple checked, but CO a likely uncommon contaminant but very lethal is rarely checked for.

You bet.

There has been a real uproar in this regard with boats of late. There have been a number of fatalities due to "teak surfing" (the practice of hanging onto a swim platform behind an inboard boat, ala body-surfing!) where the victim passed out from the high CO level in the exhaust and literally was dead before anyone could come back around and pick them up.

There have also been several instances of gas-powered generators getting people that leave them up overnight.

Diesels are less troublesome in this regard as they produce a lot less CO than a gas engine, and in addition their exhaust STINKS, so you're unlikely to get poisoned and not know it first. Nonetheless, I have CO detectors in my boat specifically because it only takes once that someone ELSE anchors next to me on a calm night with a gas genset running to never wake up.

CO poisoning is VERY likely to look like some other kind of problem during a scuba accident analysis (e.g. Hypercapnia, MI, etc) unless a coroner specifically looks for the COHb level in the blood - and without a reason to do so, they generally won't.

I bought one of the "hyper-sensitive" CO detectors for my boat a couple of years ago when a company in Canada was making them (UL bans them from being sold for "home" use here, because they "false" alarm a lot - nice to know that they don't think that 35ppm CO is a big deal, while for a fireman, its enough to don his SCBA outfit!)

They stopped, but now this other unit is available for roughly the same price. I have one those at the house to verify the gas from my compressor's output is ok in that regard, and have three (one in each compartment where someone might sleep) on board the boat, plus one in the house for general monitoring.

Its a cheap piece of equipment all things considered and provides an immediately-verifyable method of checking the health of the air you are about to breathe, at least for this possible source of contamination.
 
A: Having at least once been the guy with the after dive headache.

B: Being part of agroup seriously looking at seting up our oun fill station.

I just ordered one of those monitors. Thanks for the link Genesis
 
Good post!!!. I'll get one of those. With so many unscrupulous people out there this is a good insurance to have.
 
Genesis:
You bet.

There has been a real uproar in this regard with boats of late. There have been a number of fatalities due to "teak surfing" (the practice of hanging onto a swim platform behind an inboard boat, ala body-surfing!) where the victim passed out from the high CO level in the exhaust and literally was dead before anyone could come back around and pick them up.

There have also been several instances of gas-powered generators getting people that leave them up overnight.

That uproar has sadly come too late and is still not loud enough as there has been another ten CO boat poisonings in the States with seven fatalities only from July to October 2003. The link below provides some very sobering reading. You mention only a 'number of fatalities' from teak surfing and gas powered generators. As of October 2003 there have been 500 CO poisonings reported including 100 fatalities, far more than just a few. Many of these deaths have only come to light after the fact as CO poisonings now that the alarm bells are ringing and people have started looking more carefully at these boating fatalities. I suspect the same will start with diving fatalities where not only should the tank air be checked for CO, but the diver's blood for COHb as well. As Genesis points out a COHb level is only taken if the coroner request this and more often than not a level is not done. If you suspect CO poisoning tell the medics at the scene and the coroner afterwards. If both the tank CO concentration and the blood COHb are elevated it is bad air, but if only the COHb is high then you have a case of a bad boat.

I personally last summer had my CO Expert detector in an open plastic bag and inside a zipped dive duffle about a metre foreward of the transom on a commercial dive charter boat. After about twenty minutes on the boat with five divers sitting aft of this bag along the side of the boat the CO alarm went off. I thought this was strange as not a whiff of exhaust could be smelt and we were traveling at full power. When I took the detector out it was maxed out and this was right where I was sitting and breathing. I took the detector into the cabin and still read 35 ppm CO where the captain was sitting. Who knows what the actual level was where the divers were sitting but we all moved up from the back and made sure we were breathing fresh air although I suspect we all went down asymptomatic with 10% COHb on board. This was in a 30 foot cruiser with gas inboard and rear exhaust.

Two weeks later I was informed of another incident on a separate charter boat with gas inboard that five divers developed nausea and headache on the way out to the dive site. All except one were sitting on the transom and sides near the transom. They did their first dive but aborted the second as they still had bad headaches and felt sick. One of the divers who was a medic remarked that this must be what CO poisoning feels like. Little did he know that is what the problem was.

On TDS there is an account of two divers found unconscious below the deck of their charter boat in Florida while motoring to the dive site in a "following sea". Both subsequently recovered but the dive boat never made it to the dive site.

Personally I think the risk of CO poisoning on a dive boat is very high if anywhere near the back of the boat with a gas inboard. The problem is a systemic design one with these boats and until the public and divers are aware of this risk the potential for further poisonings and fatalities is very high. Obviously the risk to a diver with significant CO on board while diving is even greater especially if older and with heart disease. It would be very easy to miss the CO as the initial event and have the death recorded as a drowning or cardiac if the coroner does not request a COHb level.

Here is the link to the report with the 500 CO poisonings and 100 fatalaties.

CO Poisonings in Boats

Here is a link from the CDC showing that even new cruisers can have very high CO levels around the back of the boat not only while idling but while underway. There was a 'station wagon' effect on several of these boats tested.
CO in Recreational Boats

So practically what does all this mean?

Don't sit anywhere near the back of any dive boat with rear or side exhaust period while traveling to the dive site. Depending on the cabin design the 'station wagon effect can be significant.
Station Wagon Effect

Make sure the captain shuts the engine down as quickly as possible once the dive site is reached and the divers start suiting up. The CO levels are highest while idling.

Don't let any boat approach you even if idling while you are on the water. The exhaust from some of these boats can kill you in several minutes and the CO will extend quite some distance from the source along the water's surface.

Strongly suspect CO poisoning when only the guys in the back of the boat have signs of seasickness especially when coupled with headache. These folks should not dive but should be placed on O2 if available.

The CO detector above pointed this problem out to me fortunately on one charter boat this summer. It has paid for itself already. I don't think we all need to carry one but we all need to be careful where we sit in dive boats especially until these boats are retrofitted with better exhaust systems and likely CO detectors too. This will come as the legal pressure heats up on the manufacturers who have known about this problem for far too long.
 
Okay, so that deals with CO - what about CO2? Is CO2 poisoning a risk for OC divers as a result of a bad fill (not talking about breathing techniques, or RB scrubber breakthrough etc). Should tanks be tested with a CO2 meter before diving?
 

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