It’s still similar. Radon concentrations in medieval dwellings would never reach the kind of concentrations you can see in modern homes because they leaked far

It’s still similar. Radon concentrations in medieval dwellings would never reach the kind of concentrations you can see in modern homes because they leaked far more air. I wouldn’t necessarily call a tight home refining or enriching but it’s still dramatically increasing the concentration. Tunnels and caves could still be problematic though there’s a lot of gasses that can cause problems in such environments.