How long can you survive underground
Our ancestors used to live in caves before they worked out how to make proper homes for themselves and did so successfully for thousands of years. Living in a cave is not quite the same as living underground since they always have access to the outside if needed, but how long can a person survive underground in the event they cannot make it to the surface?
If someone was in a survival situation where they had enough food and water to last them for a long time, like in a bunker for example, then it depends on a whole number of different factors, most of which would be psychological.
Trapped in a cave or mine
If you were to get stuck underground in a cave or mine then air probably wouldn’t be a problem and the amount of time you could survive would depend mostly on your food and water situation. If you had ample supplies then the biggest threats would be psychological and environmental. Caves and mines both tend to have vertical drops and a million things to trip over and hurt yourself on, and when the batteries in your flashlight run out everything will have to be done in pitch black.
The psychological trauma of being in constant dark and not knowing what time of day it was and if anyone was coming for you would most likely cause a breakdown. When someone panics inside a mine or cave without the ability to see they are putting themselves at serious risk. In the event a person had enough food, water, and air then it would probably take less than a week before someone died from either an accident or a severe panic attack-like symptom.
Trapped in a confined space
If you were to be trapped in something small such as a coffin or a car covered by a landslide then your air supply would be the biggest factor. The average adult will consist in volume of between 65 and 75 liters and consumes around 8 liters of air per minute, of which about 20% is actual oxygen.
The average internal car space including the trunk and spare air space in the engine is around 3000 liters, giving you 6 hours and 15 minutes until you use all the breathable air in the car. This number can vary greatly though as children take up significantly less air than adults and the level of calm a person has in such a situation would dictate how quickly they are breathing.
Trapped in a bunker
If you had to be trapped underground then being in a pre-planned environment would be the best option. If a bunker had enough supplies to last the inhabitants then the length of time a person survives would depend on that individual’s ability to adapt to their conditions. A claustrophobic person would find it much harder to deal with knowing they can’t go outside and the main threat would come from a psychological breakdown that could lead to hazardous behavior.
In order for humans to live underground permanently the complex would have to be designed almost entirely around the psychological issues it would create. At some point, anyone who was used to living on the surface would break down in some way and even though they could survive, it would be in the most depressing of conditions. The complex would have to include a huge amount of plants and activity rooms to mimic the conditions of being on the surface, something that billionaire bunkers already have in place.
Should you ever get to see the inside of such a bunker you’ll notice many of the walls are made up of huge screens that project images of the outdoors, often being placed where a window would be in the room. Depression can cause a whole range of more serious conditions and avoiding this would be a priority when trying to house humans underground for any extended period of time.
