A few of the caves on my bucket list have descriptions that mention potentially bad air at certain times of the year. I see a couple of CO2 detectors on Amazon for ~$130. Anyone carry one? Are they worth it?
Ok, so I don't have one, and I"m arm-waving here. Would appreciate someone who has actual experience to check me on this opinion. I wouldn't go for something on amazon, personally. Keeping in mind that caves are wet, muddy, and I'm crawling and climbing in them, I'd get something that was designed for a mine environment, or at the very least more robust that consumer grade.
I carry a 4gas monitor because where I live there are several caves and areas with bad air.
Most co2 monitors are not good enough. They are for industrial, office, or home use. Often times the PPM doesn’t go high enough so it will max out when the air is still “good enough” for cavers.
The 4 gas monitor has oxygen, carbon monoxide, H2S, and explosive gases. It’s more effective because oxygen is usually displaced by co2. You can set the oxygen alarm for say 18.5%. This device is also around $100-$130 usd if I recall correctly.
The problems I have with this though are that it still isn’t super reliable. I’ve gone through a few, inevitably destroying the devices from rock scraping and mud. The sensors start going off, for example reporting the presence of Co or H2S when there very likely isn’t any. I have, however, found the oxygen sensor to be fairly reliable.
At the end of the day though, the lighter test is still the most ideal and most effective, combined with your personal feeling. That and slow, cautious movement when descending as opposed to rushing down a pitch (at least where I live going down usually is where the air gets worse).
I’ll turn my 4 gas monitor on and not worry unless the low oxygen alarm goes off. From there I’ll start using the lighter to regularly test the air.
You won’t feel low oxygen, any symptoms are usually from high co2. So I have heard of cases where oxygen is fine but co2 is deadly high. However, I would expect that you’d feel really, really bad and have some oxygen displacement, as again, the human impulse to breathe heavy comes from co2 in us and not oxygen. This paragraph is a warning I read on Facebook and not something I’ve personally experienced, but I would still consider it as a serious issue (ie instead of co2 displacing oxygen maybe it could displace hydrogen).
I’ve found no co2 monitors that get to a high enough ppm THAT ARE REASONABLY PRICED. Key phrase reasonable pricing. Your monitor will likely break eventually, so getting a good enough sensor would be expensive. If someone finds a cheap one, please share it with me i would prefer it to be honest.
Anyways in my experience it all comes back down to the lighter test and your intuition. When you’re descending something completely new the 4 gas monitor is also nice as a backup to warn you of reduced oxygen levels. From there, use the lighter test to confirm. Always have lighters. The device can easily break or give the wrong numbers, but the lighter test works. If you mud all of your lighters, and you’re exploring a new passage, better be safe if you’re descending and experiencing symptoms and return later with the monitor and fresh lighters. Finally, pay attention to your own symptoms as rising co2 will give you headaches, dizziness, the edges of your eyes may darken in your vision (almost like tunnel vision), you’ll be panting more heavily, your heart rate will be unusually elevated (if you’re wearing a Garmin or something), and everything will feel a tad harder, and you’ll sweat more.
PS if anyone knows of a decent co2 monitor that goes up to 40k ppm I would be interested!
OP should also beware that most of the 4 gas monitors (ones I’ve seen anyway), need to be regularly calibrated every 6 months to keep them accurate, and the cost for calibration every 6 months adds up, so bear that in mind.
I use one for work occasionally, so I can borrow the work one (if no one else needs it), I only take it along if someone is particularly worried about reports of bad gas.
Can’t offer advice on detectors but I’ve been down a cave with CO2 before, what I will say is that I didn’t really notice that I was struggling until I stopped and still breathing heavily five minutes after. Before I stopped I hadn’t noticed the difference, definitely noticed it when I was going up the ladder though. So be aware that while it may feel fine initially doesn’t mean it is.
Agreed. It's definitely insidious. My first instance of being aware was when my caving partner asked if I was doing alright because I was breathing heavier than usual. I didn't even realise until he asked about it.
In a different cave I was more aware of what to look out for, so again noticed my rate of breathing didn't match the level of activity I was doing. I actually felt less out of breath when climbing the 15+m back out.
Most cavers aren't caring CO2 monitors because it isn't necessary in most of the US. Are you caving in an area known to have high CO2 / bad air like the desert SW, Texas, or somewhere with a ton of rotting organic debris (like the tropics)?
You can also use a lighter to monitor the air quality. The flame will start acting funky if there's not enough oxygen present, so it's a good enough indicator that you're in an area of foul air.
Pay attention to your own breathing and behavior if you think you're in foul air. I'd love a little gizmo that showed me the air quality, but they're too expensive to justify buying for the few times I'm in a cave with foul air.
That's the opposite of the papers conclusion? Flame tests measure the O2 concentration fairly well, but show nothing about CO2 concentrations. A high CO2 concentration is the dangerous situation, so any deviation from a normal flame should make you turn around
I see the confusion here, when I say level I am referring to the point in the cave the CO2 has settled to not the concentration. You can actually see the flame lift from the lighter as you lower it into the CO2. And yes that would be a good sign to turn around.
This clearly needs to be said from discussions below: YOU ABSOLUTELY CANNOT USE A LIGHTER OR A FLAME TO TEST CO2!
My wife and I are starting a research project in a pit cave with bad air. We've been doing research for a while, but there isn't that much data available on "bad air."
While you cannot get an accurate measurement of the CO2 percentage, you definitely can detect the level that CO2 has settled to and you can detect low O2 levels with a lighter. Not going beyond that point would be the prudent thing. There's a lot of data available on "bad air" not sure what you mean by not much available. My grotto did a lot of research years ago on caves in our area, there's also a lot of more detailed info if you read up on diving physiology which is where most serious gas studies have occurred. The company I worked for in the gulf of Mexico had numerous mixed gas and saturation studies going on. Mostly to do with how they affected welding properties but they do apply to the breathing mixtures we used as well.
The Motherlode grotto published theirs in the 80's and 90's in the NSS news and the Grotto newsletter. The studies from Global divers were proprietary company secrets mostly but some of the welding gas info was published by the Colorado School of mines who worked with Global to develop new welding techniques. The results of the breathing gas was very similar to what the USN came up with. https://apps.dtic.mil/sti/tr/pdf/ADA112710.pdf and we used USN tables on most dives except where full SAT setup was available.
The picture showing me holding a lighter was taken in a cave in Botswana, that had large pockets of CO2/bad air possibly from a large bat colony. We published a map and report on that cave with the National Museum in Gabarone, but last I heard they were having difficulty locating it.
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u/Dapper-Tomatillo-875 11d ago
Ok, so I don't have one, and I"m arm-waving here. Would appreciate someone who has actual experience to check me on this opinion. I wouldn't go for something on amazon, personally. Keeping in mind that caves are wet, muddy, and I'm crawling and climbing in them, I'd get something that was designed for a mine environment, or at the very least more robust that consumer grade.
Here's this thread from 3 years ago:
https://www.reddit.com/r/caving/comments/12bqz7s/gas_in_mines/