Radon and Thoron in Kenyan earth houses, I dont know if this problem spreads to various underground railway/metro systems which are everyday and common in citie

Radon and Thoron in Kenyan earth houses, I dont know if this problem spreads to various underground railway/metro systems which are everyday and common in cities. https://www.frontiersin.org/articles/10.3389/fpubh.2019.00113/full https://www.frontiersin.org/articles/10.3389/fpubh.2019.0011... Vit D, can be replicated with UV-B flo tubes used by people keeping reptiles.