sub-slab depressurization system 5

https://mag-wiki.win/index.php/Understanding_Radon_in_Well_Water:_What_Homeowners_Should_Know

A sub-slab depressurization system pulls soil gases from under a building's concrete floor, using a fan to create negative pressure that vents radon and other vapors safely above the roofline. It's a common fix in homes with high radon levels, relying on a network of pipes beneath the slab connected to an exhaust point.