john wrote:
I guess nobody knows, ey ?

I don't know but do you have a radon problem?
Radon is a gas and remediation is blocking and ventilation.
I would have it checked first before doing anything. I would buy a test
kit and do it myself to avoid any tie in with someone that both wants to
run test and remediate. Personally, if levels are borderline, I would
do nothing as EPA tends to set exposure levels to radon and other toxins
at levels lower than necessary.