[mppm]

> Every time you look up something related to Radon, it's always cited as "the second leading cause of lung cancer after smoking"

> I wonder if that's really true.

That claim is in fact based on extremely poor research methodology. It is made by combining the linear no-threshold model of radiation damage (which contradicts everything we know about cellular repair and hormesis) with evidence from "case-control studies", a kind of retroactive hand-waving that has nothing whatsoever to do with a "controlled trial", despite the name.