Tech level: modern - like

Atmospheric pressure at local sea level:

  • Oxygen ~30 kPa
  • Nitrogen ~180 kPa

(So roughly counting 1.5 times more oxygen, 2.25 times more nitrogen)

Technically speaking such atmosphere counts as breathable, sort of. On the other hand atmosphere that we have on Earth at altitude of 4000 m also counts as breathable but not necessary convenient for the most of people.

Would it be worthwhile to place on such planet main human settlement in mountains, to provide them with slightly more Earth-like conditions, where they evolved?

Yes, I know it's a nightmare for logistics and infrastructure.

Yes, I know, I'm realistically limited to something like 3000 m (in RL highest dam built is at 3200 m; with altitude it becomes colder so there would be something like 18 degrees cooler than at surface), so I can get maybe 2/3 of sea level atmospheric pressure.

By worthwhile I mean that extra costs should be reclaimed in higher productivity, lower medical expenditures or at least higher general wellbeing.


  • In RL, even though humans can unquestionably tolerate more, passenger jets are pressurised to keep pressure equivalent to 2000-3000 m, which actually puts extra strain on their frame.
  • I'm not worried about oxygen, but whether too much of nitrogen would cause some discomfort. (Not nitrogen anaesthesia, just discomfort, dizziness or slightly impaired work efficiency)
  • Logan R. Kearsley has a good point, I should be worried about excessive amount of oxygen and newborn retina damage
  • $\begingroup$ I do think there needs to be a training to survive that kind of altitude, where will your infirmary be? Children should be considered, yes? $\endgroup$
    – Mr.J
    Mar 14, 2019 at 8:10
  • 3
    $\begingroup$ The atmosphere as described is perfectly breathable. Not even the hint of a detrimental effect on humans. And the vast majority of humans can adapt to life at 4000 meters altitude in a reasonable time -- the body reacts automatically by increasing the hemoglobin in the blood. The capital city of Bolivia, La Paz, is at 3640 meters, and the second largest city of the country, El Alto, is above 4000 meters. $\endgroup$
    – AlexP
    Mar 14, 2019 at 8:56
  • 1
    $\begingroup$ @AlexP It's worth noting that the body adapts to higher altitude levels, but these temporary adaptations produce significant side-effects in the long term. See: en.wikipedia.org/wiki/Chronic_mountain_sickness . For reference, there are a number of genetic adaptations in people such as Tibetans, Andeans and Ethiopians that reduce this: en.wikipedia.org/wiki/High-altitude_adaptation_in_humans . It's fascinating really :) $\endgroup$ Mar 14, 2019 at 9:35
  • $\begingroup$ @AlexP Perfectly? I'm not worried about oxygen, but approaching in direction towards nitrogen narcosis. (not to knock someone out, but to make a few people somewhat dizzy or unwell). $\endgroup$
    – Shadow1024
    Mar 14, 2019 at 10:03
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    $\begingroup$ You should be worried about oxygen. That level isn't enough to cause serious problems for adults, but it is enough that you could expect to see an increase in the number of babies born with congenital blindness, or developing blindness soon after birth (especially among preemies). $\endgroup$ Mar 14, 2019 at 16:05

1 Answer 1



  • Planets are big. Really big. Earth has 150 million square kilometres of land, plus even more ocean. For the initial colony effort, they need only a small percentage of that land area.
  • One million square kilometres are 1,000 by 1,000 kilometres. Enough land for mid-sized country, or a bunch of smaller ones.
  • The Tibetian Plateau is about 2.5 million square kilometres. The Altiplano is about 0.17 million square kilometres. These two examples are rather inhospitable, but a big part of that is due to the air pressure.
  • Water may be a problem with the mountaintop scheme. Few springs, and there could be limited rainfall. Still, look at snow-capped mountains and glaciers. Take a plateau in the watershed area of some mountain range.

Subsequent generations would expand to the lowlands, but by then there might be adaption to local circumstances.


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