Radon and Thoron in Kenyan earth houses, I dont know if this problem spreads to various underground railway/metro systems which are everyday and common in cities.
Geology dependent, Radon expresses from cracks in uranium rich granites and is a smoking three packs a day equivalent problem at worse and a non issue in many places.
Living underground doesn't mean you can't swim and surf in the mornings and evenings nor stop you from piping in natural sunlight via architectural means (light wells, mirror tubes, etc).
https://www.frontiersin.org/articles/10.3389/fpubh.2019.0011...
Vit D, can be replicated with UV-B flo tubes used by people keeping reptiles.