I remember that "radon killer" story being vastly overblown / debunked. Apparently anything up to 150Bq/m3 is fine or even beneficial for your health. [0]

Has the debunking itself been debunked? It's hard to keep track.

[0] https://www.osel.cz/3436-radon-neskodi-a-mozna-i-prospiva.ht...