“There is literally zero light inside caves.”
—
except that given off by bio-luminescent organisms
—
“Fire is out of the question. Either the fire burns up all your oxygen, or it chokes you to death with smoke.”
—
If the air is stagnant - not moving - then fire would burn it all up. However, if the air is stagnant, then people in the cave risk death where pockets of air have been used up by the surrounding rock over time. Which is why smart cavers carry oxygen meters - to avoid what amounts to instant death - air here, then one step more, no air.
So obviously, this cave system has moving air. Else everyone on the expedition would be dead and we would not be reading this report.
Since that is the case, there is no problem burning torches.
Its not a zero sum game; its not addressed in “scientific literature” because it is common sense.
It took several years of preparation before exploration was considered safe.
No one understood how our pre-human cousins could do this without light.
Eventually, evidence of fire was discovered in the fossil area, - but no where else.
Perhaps the fossils belong to victims of asphyxiation, which might explain their highly preserved condition.