radon in basement 4

https://iris-wiki.win/index.php/Understanding_Sub-Slab_Depressurization_for_Radon_Mitigation

Radon in basement is a serious concern because it's a radioactive gas that can seep up from the soil through cracks in the foundation. Since it's odorless and invisible, the only way to know if you have a problem is to test for it. Long-term exposure is linked to lung cancer, so if levels are high, you need to mitigate by sealing cracks, improving ventilation, or installing a radon removal system. It's definitely worth checking, especially if you spend a lot of time downstairs.