What are the physical effects of a person living their entire life underground, and how would it affect them if they ever came up?

Question

In my world, a group of high-ranking politicians and military officials (along with their families and a few skilled engineers) realized that WW3 was imminent, and decided to bunker-down, big time: Using the most state-of-the-art technology, they built an impenetrable underground fortress, and remained within it for about 200 years.

About 180 years in, a woman named Christina Anders is born, unaware of life on the surface. But the surface dwellers still exist, and after encountering a group of them, she decides she wants to go up.

The surface is a wasteland. The region they’re in is a giant desert basically, with only a few scattered regions of fertile plant growth, and dozens of still existing radioactive hotspots.

This question came to me the other day: since Christina grew up underground her entire life, would this have any dire effects on her survival in the wasteland? If so, what are good ways for me to deal with said problems?

Context- The bunker dwellers live underground enclosed within the bunkers confines. I imagine something like a small underground town, made of metal and concrete. They have air, and lighting and whatnot, and are completely self-sufficient, growing food and producing/recycling water. Also all this is done with modern day tech.

Answer 1

Crippling hayfever. Possibly anaphylaxis.

When apollo 17 astronauts were exposed to dust particles their immune systems had never experienced before, they had really bad hayfever. Your people have had purified air for generations, new pollen and dust will panic your immune systems.

You will hope you have kept some anti-histamines in reserve, as you'll probably need to take them for the rest of your lives.

If you're lucky, you'll only get symptoms outdoors in Spring. If you're unlucky, youl'll need to take it year-round.

Supplement overdose

Assuming there previous diet was perfectly optimal (including supplements for things like vitamin d), and they come up and continued that diet, while getting exposure to lots of sun, they'd be a low risk of:

• vitamin d toxicity.
• hypercalcemia, or high blood calcium levels(digestive distress, such as vomiting, nausea, and stomach painn fatigue, dizziness, and confusion, excessive thirst, frequent urination)
• nausea, vomiting, poor appetite
• Stomach pain, constipation, or diarrhea
• Bone loss
• kidney disease and or failure.

Although this would take a long time to show up, theyd probably stop taking high levels of supplements long before it became an issue.

Pandemic

You're bunker population, and the outside world, have gotten different viruses evolution over the 200 years. Merging these two biomes back together you'd see an outbreak of a new disease through your population. It may be a mild cold. It may be smallpox.

Mental health issues:

• They'd find sleep very hard, their underground world was loud from machinery / air flow and dark, night in the wild is silent and, with the moon, can be quite bright.
• Some may be scared of open spaces.
• They'd have no sense of predators, and while they will be hunted by wolves, but wont be able to read the terrain / sounds / etc. They will be paranoid about any unexpected movement.

Unable to read what their bodies are saying:

• Rain / snow / cold / exposure / frostbite / hypothermia would be a foreign concept. They wont know warning signs.
• Highly suspectable to Heatstroke / sunburn. Also wont know warning signs.

Other:

They'd also he unfamiliar with the new environment and its risks, which would also affect them physically indirectly:

• Their eyes would struggle with bright sun. This would take a long time re-adjust.
• Theyd have no sense of direction and will get easily lost. Theyd have no long distance sense of distance either (that mountain looks so close!)
• Theyd be unable to walk or run long distance, even if relatively fit, having never walked more than a few hundred meters a day, the muscles wouldn't be used as much and they'd get sore muscles very quickly. (Depends on bunker layout)

Answer 2

Assuming that the group will be able to steer her away from potential fatal errors from ignorance, here are some problems she may face:

1. Agoraphobia. Even if they had fairly large caves, the sky is far larger, especially since she's in a desert and there's no clouds. Slow acclimatization may be her best bet.
2. Eye issues. Much will depend on how bright the lighting is in the fortress, but they will not illuminate it as brilliantly as the desert can get. Sunglasses are important if possible. Otherwise she may have to try to stay inside during daylight hours, or use cloth to filter light
3. Sunburn. She has never been exposed to the sunlight's intensity and will burn badly. Sunscreen may not feasible in this era, so she may have to use clothing to protect herself, or avoid the bright days.
4. Heat and cold. Deserts tend to have severe variation between night and day in temperature, and she's not used to it. Following the guidance of her companions on clothes will help.

Answer 3

If it is indeed a well-constructed underground habitat with sufficient ventilation, lighting, food production, medical facilities, and carefully managed population, there should be no physical effects at all. Ms Anders would lack only practical skills needed to navigate the outside world and communicate with surface dwellers.

It is fathomable that she would feel uncomfortable in big open areas or under a plain sky. But this is not necessarily a long-term condition. Once she adjusts to the new environment she should be completely fine.

I think that the only realistic possibility is lower resistance (up to no resistance) to bacteria/viri. Your bunker might be too clean and do not have enough microbial life for Ms Anders to develop immunity to pathogens common in the outside world. It is also probable that some bacteria/viri mutated in the past 180 years. If it is the case, she might also have some problems with indigestion while her digestion tract is being populated with the correct bacteria.

Answer 4

Apart from everything else: it's currently speculated that eye development is tied to sunlight, specifically the eyeball proportion gets out of whack if a person is too much in dim-ish light in their youth (compared to the outdoors). The result is myopia because the image is not focused on the retina despite the lens' capability.

Dunno about any developments in supporting or refuting this hypothesis.

Answer 5

They would suffer from a radical shift in their circadian rhythms.

Our normal cycle of sleeping and waking up is based on a number of variables, but the most important is when we are exposed to sunlight. Without that external feedback people would adopt very different patterns, especially if they are underground their entire lives. When experiments were done where people were isolated in a dark cave for months on end they completely lost track of time, occasionally sleeping for over a day at a time without realizing it. This may be mitigated when there is a societal structure that could keep each other in check, but there is no reason they would live on a 24 hour cycle.

Coming up to the surface they would suddenly be exposed to a day/night cycle on a strict 24 hour cycle, which could completely upend the way they live. At best this could feel like extreme jet lag to them, but more likely their bodies would have no ability to adjust to the new cycle. This would be like a surface dweller suddenly trying to switch to a 30 hour day. It would be very disorienting and would feel like a constant jet lag over and over. It could take weeks or months to stablize, and some people may not be able to adjust at all