radon testing company
https://www.google.com/maps/d/edit?mid=1G_Mw2jTcBAGJImxacwD8gI6hIBgmbF1i&ll=36.149675830165805%2C-86.76874635000001&z=17
It seeps up via the pores and cracks of a structure and wall surfaces. Block walls are more susceptible to radon entrance because they're much more porous and also thus, thought about a weak water obstacle.