Wayne Dean, JD
Fort Myers, Florida USA
Concrete emits radon. Exterior curtain walls of porous concrete blocks have lots of surface area from which radon can emanate. If the exterior of the blocks is sealed, radon emissions are released only to the interior and into the space between the drywall and blocks (exterior wall cavities). Such exterior and demising wall cavities may become radon reservoirs. It is not uncommon that air-condition duct leaks will drive or draw the radon-rich wall cavity air into the breathing zone. Air handler operation commonly “mines” radon from the exterior and demising wall cavities and injects it directly into the conditioned air airstream. A radon “extraction” system can continuously extract this radon-rich wall cavity air and exhaust it directly to the out of doors. Reducing the pressure in the wall cavities will inhibit radon migration into the breathing zone through unintentional openings in the drywall interior pressure envelope.