Hello Steve-

You may be referring to sub-slab depressurization, instead of sub-slab ventilation. You may find my discussion on it interesting: Radon: Truth vs. myth

Yes, the technique is a proven method for reducing radon.

Not that it matters much.

Cheers!
Caoimhín P. Connell
Forensic Industrial Hygienist
Forensic Industrial Hygiene

(The opinions expressed here are exclusively my personal opinions and do not necessarily reflect my professional opinion, opinion of my employer, agency, peers, or professional affiliates. The above post is for information only and does not reflect professional advice and is not intended to supercede the professional advice of others.)

AMDG