Did this forum save my life?

[jeffkruse]

In a recent thread I learned about the “Naked Flame Test”. I decided to try it in a local cave.

This cave is called Cueva Cucaracha and has been visited by many people. It’s joked that once you visit it you never go back. This cave has an estimate of over ½ million bats. It’s extremely hot and humid. It’s been measured at 95.5 degrees and 100% humidity. The cave has large borehole passage where all the bats are. A small dry stream passage runs along left wall and heads off to walking/stooping passage which is much cooler (80 degrees) for some distance then the old cave passages get bigger and bigger. It’s a significant cave system.

This time we brought some lighters and candles. We got to the cooler section in about 5 minutes and rested. We tried to light the lighters and couldn’t get them to light. Even though I was only breathing a bit heavy I was comfortable but freaked out that the lighters wouldn’t light. Another caver wasn’t “happy” either. I opted that we leave and upon turning around I missed the climb-up that lead out. I shouted to the group staying and they also decided to leave at that time. We had a CO2 meter but it only goes to 10,000ppm and pegged immediately upon entering the cave.

After leaving the cave a few of us decided to go back in to see when the candles would go out. We lit candles at the entrance and found about 40 meters into the cave the candles went out and the lighters would not light.

What we “know”, the O2 was <14.25%, the CO2 is >1%, the temp was >90, the humidity was 100%, Many people have visited this cave for many hours, bat’s thrive in this cave, guano covers everything.

If a lighter wont light do you get out right away?

[Scott McCrea]

Intresting. I have always heard that if you think there is low O2 or high CO2 you should get out asap. But, now you're saying that people stay in the cave for hours and bats live there. Maybe conventional thinking needs an update?

[jeffkruse]

Yes many people have done this cave at all times of the year. Some have stayed ½ day in there. I have done it 5 times but one of those times must have been very high CO2 because immediately upon entering the cave we could not catch our breath. We stayed about 15 minutes resting in the cool area before we left the cave.

I would have been ok had I not done the naked flame test. People can take lower O2 levels than 14% easily. However not knowing that it was above 12% freaked me out.

Low O2, High CO2, High Temp, High Humidity, High ammonia, are only some of what this cave has to offer.

[captnemo]

Glad to hear you exited safely.

Intresting. I have always heard that if you think there is low O2 or high CO2 you should get out asap. But, now you're saying that people stay in the cave for hours and bats live there. Maybe conventional thinking needs an update?

Definitely not!
Here's the problems with that line of thinking.
Firstly reactions to CO2 levels are unpredictable, what one person can tolerate with only mild discomfort can cause others to become unconscious. In either case thought processes/judgement may be impaired. Now when your not thinking clearly is not the time to decide whether you can cave safely.
So when you see that the lighter won't light it is possible that you could continue caving, it's also possible you could wind up dead. Why take that risk?
People can tolerate heavy CO2 and survive and then proceed to feel like they have the flu for several days as their bodies try to recover, since they felt ok when they came out of the cave it must not be related? Blood tests have shown that it can be, and long term damage to vital organs have been documented.
(oh and the bats?, they're on the cieling unlike us, so are above the co2 and have a lifetime of exposure to adjust so that is never a good indicator of conditions)

Heres a paper on the BLM website that details some of the effects/ risks involvedhttp://www.blm.gov/pgdata/etc/medialib/blm/wy/information/NEPA/cfodocs/howell.Par.2800.File.dat/25apxC.pdf

So while the flame test is only an indication of O2 levels its a fairly reliable indicator that air quality is less then optimal and it is always best to er on the side of caution. If you really felt the need to proceed then breathing apparatus would be the way to go.(and proper training on the use of such in confined spaces)

[chac]

Jeff,

You mentioned a dry stream passage on L wall. Does it ever become active? Do you find any static sump pools or other entrances in Cueva Cucaracha? Were your eyes smarting from the ammonia?

I have been in what appear to be somewhat similar dry caves on the Yucatan Peninsula. A few caves host extremely large bat populations with 3-5 foot deep guano floors, while some caves have very small if any bat populations. High humidity, high temperatures, and limited air exchange are common factors where low O2 or high CO2 levels environments are found in the tropical caves I am familiar with.

Bats and ammonia seem to be a variable in some "bad air" caves. Perhaps the ammonia lends its own character to the environment. Ammonia combined with oxygen produces Nitrogen Monoxide, but I am not familiar with in what concentrations. Aerobic bacteria may also be using O2 as they chew through the guano on the floor. Another variable in Yucatan caves are the number of static sumps in the cave (they off-gas CO2; look for calcite rafting on the sump surface). These sumps can push the CO2 level pretty high in some Yucatan caves. CO2 levels always increase the closer you approach a sump. I do not have a meter to qualify these observations.

I've always managed to get a flame from a Bic lighter in these caves, sometimes it took a few attempts just to get a flare. I have also noticed that O2 and/or CO2 levels in the cave can change on a daily to monthly basis. Perhaps this is weather related?

If you were uncomfortable, then I think you made the best decision to leave the cave. You could carry a small pony bottle and regulator the next time you go to Cucaracha if that is an option.

Jim

[jeffkruse]

I want to clear up the misconception about CO2 “collecting”. Gasses disperse quite rapidly from their point source. Certain conditions can “trap” them but in those cases the point source has to be producing more than can be dispersed. The bats in this cave could be the main point source of CO2 or at least a major contributor. The CO2 in a room without restrictions will be even if the point source does not produce CO2 faster than it can disperse.

Lets say it’s the mounds (some very tall) of guano producing a lot of the CO2. It would disperse evenly to the ceiling as it was being produced.

There are no other entrances that are known. The room/passage with the bats is large borehole passage. A stream can flow through when it rains a few inches. Just guessing but the flow could be 1 – 50 cfs. There are a few static pools with stewing rotting bats that we have to get neck high in. That is a restriction to the rest of the cave and the temperature drops 10 to 15 degrees at that point but the lighters still did not light. The rest of the cave has a small river flowing that could bring more CO2 or more O2 to the cave. We don’t know.

I know I am a “medium” caver. I take some risks but I do chicken out easy to. I wanted to see if there were a number of cavers who just push on when the naked flame test fails. Maybe I should make a poll?