An inexpensive butane lighter can indicate the underground presence of invisible, odorless, carbon dioxide and can help cave visitors avoid death by asphyxiation.
Many years ago I had a chat with Dr. Merlin Tuttle, founder of Bat Conservation International. When I asked him about close calls underground, Tuttle cited a near-death experience in a Texas cave.
Tuttle and a friend had worked their way down to the lowest part of the cave. Suddenly each of them simultaneously mentioned that he was finding it difficult to breathe and feeling extremely tired. Fortunately, this reminded Tuttle of an article he had read on the symptoms people experience just before they die from exposure to carbon dioxide.
Tuttle grabbed his companion and the two of them headed for the cave entrance, which they were barely able to reach in their weakened condition. They both collapsed outside the cave and were able to stand up only after several hours of breathing fresh air.
Controversy surrounds the cause of carbon dioxide buildup underground and both rotting vegetation and bats’ breath have been named as culprits. However, one thing is sure. Because it is completely invisible and completely odorless, an underground “lake” of carbon dioxide poses a mortal threat to anyone who walks or crawls into it. Carbon dioxide, in fact, has been called “the silent killer.”
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