sub-slab depressurization system

https://kilo-wiki.win/index.php/What_Homeowners_Need_to_Know_About_York_County_Radon_Testing

A sub-slab depressurization system works by creating a vacuum beneath a building's concrete floor to pull soil gases, like radon, away from the structure and vent them safely outside, typically through a pipe running up the side of the house. It's a quietly humming, low-maintenance setup that pros often install during construction or retrofit into existing homes, using a fan to maintain negative pressure so the air inside stays cleaner.