> It's only when you start refining and enriching natural things that they become really risky.
It’s a big factor, but not only. You don’t need to refine or enrich anything to have radon poisoning, for example.
It’s a big factor, but not only. You don’t need to refine or enrich anything to have radon poisoning, for example.
Tunnels and caves could still be problematic though there’s a lot of gasses that can cause problems in such environments.