Note that a basement doesn't necessarily matter. We have slab-on-grade and our radon levels are borderline "do something about it" - our yearly average seems t

Note that a basement doesn't necessarily matter. We have slab-on-grade and our radon levels are borderline "do something about it" - our yearly average seems to be around 2.0. We went with https://www.homedepot.com/p/Airthings-Corentium-Home-Battery-Operated-Digital-Radon-Detector-223/313732652 https://www.homedepot.com/p/Airthings-Corentium-Home-Battery... which the other commenter suggested as a more expensive solution. I bought this because California county Radon maps showed us in a "tan" area, meaning "moderate" risk of Radon above 4.0. Here's an example of one such map: https://www.conservation.ca.gov/cgs/Documents/Publications/Special-Reports/SR_194-Radon-Map.pdf https://www.conservation.ca.gov/cgs/Documents/Publications/S... Note that radon levels varied greatly in our house by both weather and time of year.