How Long Can Humans Survive in a Cave?
12 youth soccer players and their coach, who were missing for nine days, were found on Monday. This photo, released by the Royal Thai Army, shows the first moments after they were found by divers in the Tham Luang caves of Thailand.
Credit: Royal Thai Army/EPA-EFE/Rex/Shutterstock

This story seems like it's on its way to a happy ending: The youth soccer team and its coach in Thailand that had gone missing in the Tham Luang caves for more than a week have been found. The team had been on an outing, exploring the cave, when heavy rains hit and flooded the subterranean space. But on Monday (July 2), rescue teams located the soccer players and their coach huddled in an air pocket in the cave, according to the BBC.

Now, all the rescuers need to do is get everyone out — a process that could take months because of the flooded conditions, the BBC reported. But the group has already been stuck for ten days, so how long can humans survive trapped in a cave?

It depends on the type and location of the cave. But generally, running out of oxygen is not an issue, said Andrea Rinaldi, a biochemist at the University of Cagliari in Italy who, in part, researches how humans adapt and physically perform in cave environments.

"Oxygen is usually abundant [in caves], even hundreds of meters below ground," Rinaldi told Live Science in an email. "It flows through cracks in the rocks, and through porous limestone." [The 7 Longest Caves in the World]

That said, in rare cases, there can be pockets in caves where carbon dioxide can build up, making the air unbreathable, said Rinaldi, who is also a recreational caver, or spelunker.

But these types of pockets are very different from the one that the team was found in, he said. That pocket, Rinaldi said, is likely large, so there would be enough oxygen to sustain the group for a long period. "But air quality in the chamber is certainly a parameter that rescuers should monitor from now on," he added.

If caves are very dry, for example, there can be a lot of dust in the air. And in some tropical caves, decomposing bat guano (poop) can release ammonia vapor into the air, and may also spread fungal spores, which, if inhaled, can cause respiratory issues. "Apart from these particular cases, however, the air in a cave is perfectly breathable," Rinaldi said.

As for other essentials, humans need food and water to survive anywhere. The team reportedly had very little food before the rescue teams arrived.

However, "a human being in good health can survive weeks, or even months, without any food," Rinaldi said. That's just as well, because there is "no food for humans in a cave," he said. Though many caves are filled with bats, and sometimes birds and fish, the animals are all "extremely difficult to capture," he said.

As for water, that's a more "delicate matter," Rinaldi said. In caves, there's usually high air humidity, which reduces the tendency to drink, Rinaldi said. But humans still "absolutely need it" every day. In the Thailand cave, the "water would probably be muddy," he added. So, if stranded people don't have a device to filter the water, it would be "much cleaner and safer" to sip the water that drips from the cave's ceilings and walls, he said. (Now, the rescue teams are providing food and water to the Thai soccer team.)

Temperature could also be an issue in caves, but not in this instance, Rinaldi said. "Hypothermia is another dangerous foe, but [in] this particular case we are dealing with a tropical cave, so temperature should well be above" 20 degrees Celsius (68 degrees Fahrenheit), he said.

In addition to the physical challenges of being trapped in a cave, there are psychological ones as well. "Being trapped underground for ten days, in the dark…with [little to no] food can be a harrowing experience for anyone, including veteran cavers," Rinaldi said. [Photos: Amazing Caves Around the World]

"The first images brought to the surface by the [rescue team] who found the boys do show a very calm party, which is very reassuring," he added. Also, the fact that they are a team, stranded together, will probably bring them some comfort, he said. And now, phone lines will be set up inside the caves so that the boys can talk with their families, according to the BBC.

Experts are saying it could take weeks, even months to rescue the boys, according to the BBC. Rescue teams are currently gauging their options: either wait for the children to recover their strength and teach them — none of whom know how to swim — how to dive through the flooded passageways, or wait for four months until the water recedes.

Originally published on Live Science.