radon in slab foundations

https://theradonmitigationstonepost.valoradigest.com/posts/how-radon-mitigation-for-stone-foundations-differs-from-other-homes

Radon in slab foundations is a concern because this radioactive gas can seep through cracks in concrete slabs and accumulate indoors. Testing is the only way to know if levels are high; mitigation often involves sealing gaps and installing a sub-slab ventilation system.