Follow
> or is it purely geology
In these two specific cases it's purely geology but magnetic field of Earth stops a lot of cosmic radiation, so altitude and latitude also matter a lot. On the poles you got more radiation, high in the mountains you get more than on sea-level, in plane even more, but it still has zero biological effect at these doses. If you're interested, this is probably the most informative lecture:
https://scitech.video/videos/watch/60a7b2c5-739b-40ac-8ab1-009d1aa653cd