This is definitely worth it. We tested our place (south side of Berwyn) during the buying process five years ago and found high levels of radon. Had a mitigation system installed, paid for by the sellers.
How in the world does a mitigation system work? Did you test for Radon level after it was installed?
Radon is an insidious gas, in that it cannot combine with any other element (inert, or "noble gas"), thus trapping it by combining with something else is not possible. If one knows the exact source, some stonework, or masonry which can be isolated, and possibly removed, that gets rid of it, of course. If the masonry of the whole structure contains Radon-emitting materials, it's real difficult.
Long-term breathing of Radon is known to cause lung cancer. It is emitted in quantity by Radium, which was used for many decades to coat watch & clock dials, as the Radon emitted glows in the dark. A small chunk of Radium (pretty rare, and very expensive) sitting in the darkness, with no air drafts present, has a tiny "cloud" of Radon gas hovering around above it's surface; if you blow on it, it wafts away, no glow then, and presently it begins to return again, ghastly-looking sight, for sure! One of the damndest things I've ever seen! berwynson
