A while ago I tried to design my own sustainable house to shelter myself from incoming climate disaster (took into account geopolitical location, access to resources, ecosystem, the cultural value system in the place, accessible technology and compromises, etc) As sustainable and self-sufficient as it can get according to what science/technology has discovered so far. I learned about ground radon radiation and how we are ignorant/oblivious about its dangers. It seems to be a bit late but it may be important to do a radon radiation survey for the ground where your house is built on (it should have been done before buying the land). There are still solutions to improve the foundations of already built houses to protect from this potentially dangerous effect. It depends if the ground you built your house on has significant radiation (direct and through water from the well).