When I suggested not to get me started it was for several reasons, mostly involving economy and degree of relevance to the geographical conditions, legal and procedural, to the Post specific situation. If it sounds like i'm attempting to weasel-out I'm not. Laws and codes regarding testing, detection response, and prevention/remediation requirements and methods vary, sometimes significantly, from state to state.

Not being a certified or even qualified Radon specialist by any stretch, I could merely relate my experiences enforcing NJ regulations and system designs acceptable in my state alone. So far as the effective accuracy degree of the results from one of these OTC kits, our laws require receipt proof of on-site testing by a state certified lab--usually with the total costs line being redacted, and we officials are not allowed to request a viewing of the test results. Readings from store-bought kits are legally irrelevant. My responsibility is to witness that the installation of the design professional's approved solution was completed in strict accordance to the specifications.

I suggest Googling: Radon Laws, {your state}. In the process of wading through sites ultimately with the purpose of selling a service or device, you could still sift out more pertinent info than I could supply, unless of course you live in NJ, but don't hesitate to be curiosity driven. Radon is a gaseous form of radiation caused by the degeneration of trace amounts of Uranium usually found in igneous rock and surrounding soils--and is pegged as the second leading cause of lung cancer in the US!