Tested for Radon a few years after home built. Radon level was 38pCi/L.with Passive Radon system.
Val gave me advise and I purchased materials from this site. RP145 fan installation and sealed sump pump pit per directions.
New short term test results are less than .7pCi/L. Low enough to NOT register on charcoal test!!
Thankful for Val and this site!