active sub-slab depressurization 2

https://myradoncrawlspaceinsider.evercolumn.com/posts/why-radon-in-crawl-space-homes-needs-a-different-mitigation-approach

Active sub-slab depressurization is a radon mitigation technique where a fan creates negative pressure beneath a concrete slab to pull soil gases away from the building. It's commonly installed in homes with high radon levels, using a pipe system to vent the gas safely outdoors.