Radon from *SEALED* Granite Countertops????


With the up and down stories on radon emisions from granite countertops there is some questions that this brings up. Radon occurs from the natural deacy of rock and soil. When radon enters a home from soil, we have seen it posted that it enters the home thru cracks in the foundation or basement, and other "leaks" into the home from the foundations slab.
If this is the case, and radon is actually a GAS, how can it escape from a SEALED granite countertop??? Since most all granite countertops are totally sealed against bateria and so contaminants cannot contact the granite itself and stain it, how can a gas escape this sealed confinement????
Just curious how this happens since it doesn't enter homes except thru leaks or cracks in the foundation.... thanks!
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And where did you get this idea?

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infiniteMPG wrote:

Radon travels through solid concrete because concrete is porous. More comes through cracks, true, but Radon will migrate through (not as solid as it seems) concrete.
As to whether Radon will migrate after "sealing," it will. The Radon atom is smaller than the distance between the molecules of the sealant. Same way Helium leaks from a rubber balloon.
It is possible that some sealant could effectively become one giant molecule, similar to thermosetting plastics like Bakelite. This WOULD trap the Radon within the sealant. Don't forget, the ENTIRE item must be "sealed." Doesn't do any good to seal the top and leave the bottom raw.
I suspect the best method of "sealing" a granite countertop is to encase the countertop in some fairly dense metal, such as stainless steel.
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The currently accepted conceptual model for vapor intrusion is that soil vapor migrates into buildings through the seams between the slab and walls, and through slab penetrations (i.e. toilets, bathtub and sink drains, other plumbing, electrical conduits, &tc.). Older models used to consider cracks in the slab, but these are obsolete.
Diffusion through a concrete slab is glacially slow. I bet there'd be more radon generated from the aggregate in the slab than what would come though solid concrete from the subsurface.
I haven't done the calculations, but I'd bet that the amount of radon generated from 8 or 10 cubic feet of granite counter top would be negligable, as would be the amount of radiation produced by the generation of radon.
-Zz
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Granite is very porous and even "sealed" will leak. You should disinfect your countertop often .

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First, the top sealing will never be perfect and gas proof, second the bottom is never sealed and could, in theory, off gas quite easily.
Also, in most areas, concrete in the home is made with crushed granite stone, this can off gas as well. Compared to a few hundred pounds of granite countertops, there can be several tons of granite within concrete.
This all sounds like an urban myth. Many homes have no detectable radon despite the use of concrete in the building. While possibly some homes may be made with some radon off gassing granite, it probably would be barely detectable. Most homes with granite aggregate concrete and countertops probably only have a few molecules of radon if any and be considered radon free.
Most radon problems have the gas seep up through the soil from the base of millions of tons of stone in the planet under the house not from the building materials, unless someone can locate actual tests to prove otherwise.

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Al Gerhart had written this in response to http://www.thestuccocompany.com/maintenance/Radon-from-SEALED-Granite-Countertops-334746-.htm : One of the countries leading Radon researchers, Dr. Kitto of New York State Health Dept, did a test where he placed a very dense, non radioactive stone over a hot stone, sealing a Radon meter on topof the dense, Radon free stone.
The Radon from the lower stone came right through. He repeated the test with an old Radon water jug, cold, non Radon producing stone placed over the jug, with the meter sealed tight against the top of the cold stone. Again the radon seeped through the stone.
On one thing, the MIA can be trusted, their care and cleaning instructions on their website. They state that granite can not be sealed vapor tight without damaging the stone, and they say sealer allows a few seconds to carefully blot up the spill. They sealer will not prevent staining.
Now your statement that granite is somehow sealed against bacteria is also completely wrong. NASA produced a study where they proved that bacteria lived WITHIN the stones. They used DNA data to prove there were entire families of bacteria, proving that they were breeding withing the stone's pores.
Radon is produced by the uranium decay, with the uranium being mixed in the stone itself as well as being on the outside of the stone. Since stone is not a barrier to gas, any Radon produced will find it's way out due to osmosis and gas pressure building within the stone.
Best keep looking for info on this topic rather than believe the stone industry. Way too much money at risk, plus the have sucessfully covered this up for the past 14 years. They cant tell the truth, so they keep digging the hole deeper. If this was a non issue, neither the CRCPD (state radiation officials) nor AARST (radon scientists) would have committees seting maximum allowable radiation/radon levels for stones and measurement protocols. ANSI and ASME are also looking into the controversy for their organizations. On the radon issue, we have a full scale radon test going currently, over 10 pCi/L so far from only 18square feet of granite in a 96 square foot room. That is like smoking 1 1/2 packs a day, http://forum.solidsurfacealliance.org/viewtopic.php?f=7&t ST
We have a lot of info on the topics available. forum.solidsurfacealliance.org solidsurfacealliance.org/blog solidsurfacealliance.org
If it is so safe, why are they fighting the testing effort?
forum.solidsurfacealliance.org ------------------------------------- infiniteMPG wrote:

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