PROBLEM: Some multi housing has radon issues. Is it possible to extract accumulating radon directly from the building’s “radon reservoirs” all at once? Without having to add hot, humid outdoor air (mold risky) or expensive dehumidifiers, energy recovery ventilators ERVs or heat recovery ventilators HRVs? (high energy consumption)
Recent research has demonstrated that it is possible. SEE Testimonial from DL
It is a well-known and undisputed fact that radon is emitted from masonry blocks used in construction of both low and high rise residential buildings. And that explains why radon is common in upper floors of high rise condominiums in south Florida and other places.
Because of their porous nature, masonry blocks have very large surface areas from which radon is emitted from RADIUM226 that is almost always present in concrete raw materials. Result? Masonry blocks emit relatively large quantities of RADON222. Especially when compared to smoothly finished and polished, non-porous granite.
When masonry blocks are used as exterior walls including multistory curtain walls, the exterior of the wall is usually finish-coated with an elastomeric material to prevent rain water and condensation from soaking into and wetting the wall system. But such coating caps and prevents the escape of radon into the atmosphere, causing radon to be captured and to accumulate within the voids in the wall to surprisingly high levels.
Result? Such unintentional radon storage reservoirs can become filled and refilled with radon quickly rising to relatively high radon concentrations.
In most new construction, exterior walls are finished with an airspace of about ¾ of an inch behind the installed drywall or sheet rock. This void is relatively airtight and faces directly against unfinished, highly porous masonry blocks. Result, almost all of the radon emitted by the masonry blocks is captured and concentrated in these “closed spaces/reservoirs” between the elastomeric exterior coating and the interior drywall over time.
However, this is not necessarily a problem as radon and radon daughter products must come into close contact with soft tissue before it is harmful to building occupants. And captured behind drywall, it certainly cannot reach the occupants.
Or can it? Unfortunately air conditioner operation creates both negative and positive pressures within the building structure.
Because of installation/construction difficulties, it is rare that the negative pressure or return side of an air handler does not reach into and pull air from the wall cavities which are all interconnected. And when it does, it easily pulls the radon rich air that has collected in the exterior wall cavities and then pushes/blends it right into the conditioned air air stream. In effect, it is very common for an air conditioning system to unintentionally and unknowingly “mine” radon from places within a building where it has been captured and then force it into the breathing zone placing occupants at risk from radon exposure . . .