Hi George- Your state radon contact for NC is Phillip Gibson 828-761-1780 phillipdotgibsonatdhhsdotncdotgov

thank you

ok so one more question... may sounds stupid but I'm gonna ask it any ways. If radon is a by product of natural nuclear material breaking down under ground and is considered a radioactive gas, Why are we not piping it through a more suitable pipe so there is no radioactive leakage into surrounding materials. Maybe even the pvc pipe wrapped in maybe some form of reflective blanket? i just thought I'd throw that out there.

Interesting question. I'll take a stab, if anyone finds something wrong, feel free to correct me.

Radon, though radioactive, is a noble gas. Which means it's chemically inert. It doesn't really interact with anything, although it sticks to charcoal for some reason because apparently everything sticks to charcoal (I'd love for someone to explain that bit to me). The only real leakage you would be concerned with is not having an airtight system where air, including radon, would get pushed/pulled into the house. I assume PVC is non-porous so that you won't have any emanation through the piping material, so as far as I know, so long as you have an airtight system, nothing is going to "leak" into the house.

But since you got me thinking about it, I wonder how much of the radioactive decay products, which are "sticky," end up sticking to the inside of the PVC pipe. I wonder, if you've had a system that's been active for a number of years, or if you have active systems that are mitigating houses with extraordinary radon sources, how much of the decay products are deposited throughout the system. Maybe you would be able to detect gamma coming through the system piping/fan housing? Hmm. Just thinking out loud here.

Ryan is correct that the piping is airtight (or at least should be and we operate under the assumption that it is installed properly). So, no radon is going to get out. I'm assuming that your question is more directed towards a concern about radioactive decay coming through the pipe. The alpha particles that we are mostly concerned about as a cause of lung cancer, can't make it through the pipe. Gamma radiation could make it through the pipe. Ryan brings up a good question about radon decay products "sticking" to the inside of the pipe. Without a significant build up of decay products, there wouldn't be enough gamma to be a concern. I'm assuming the surface area isn't great enough for enough decay products to build up to a point where gamma emissions are significant, but I don't know the answer to that. Maybe @Shawn Price, @Leo Moorman, or others could answer that.

Let me take a stab at this, (I am sure their are others that could be more eloquent).
There are three major types of nuclear radiation;alpha beta and gamma. Each of them delivering a different "dose". The pipe walls themselves are are shield from almost all of the dose from Alpha and Beta radiation. Shielding for Gamma requires significant layers of lead, or concrete or lots of water. when we did work in the nuclear plants we used lead bricks that were 2"x 4" and could build up a wall to protect workers sometimes several layers thick. the workers building the lead wall would get dosed but that was managed as well i.e. plywood sheets went up then first layer of bricks then second layer of bricks. The workers doing the required work would get dosed at a significantly lower level because of the lead bricks between them and the gamma source. Dose is a factor of exposure level and time exposed. Gamma energy dose is considered to be is straight line from source and distance from source without shielding is a factor for dose as air itself is a shield from gamma radiation.
The gamma radiation from radon emitted while traveling through the pipe, would be partially blocked by the pipe wall itself but most would continue on through, but it would be my guess, there would likely be less gamma transmission through the air than would have been there before SSD system was installed, from the radon decay in air that was occurring.
(that was probably too technical)

Radiation from radon that concerns us most from a health effect point of view is the decay products of radon that because they are electrically charged stick to lungs really well (like a band aid to a hairy arm) and stuck to lungs they will likely cause damage to lung cells as they go through radioactive decay, giving off alpha beta and gamma radiation.
Radon itself will cause similar damage by going through its decay process while in the lungs or while in the bloodstream.

My mentor (Thanks Terry) taught me that Alpha radiation has 30X the relative biological effect to gamma or beta radiation, but only had enough power to penetrate about 1 cell deep. That is why alpha radiation does not cause a lot of skin damage (top layer is already dead cells) but does cause significant damage to live lung tissue. It would be my guess, there would likely be less gamma transmission through the air from the radon inside the piping than would have been there before SSD system was installed, from the radon decay in air that was occurring.

You are correct regarding the lack of surface area in the mitigation pipe. We see gamma concerns when we use GAC treatment for radon in water because we typically start with a few thousand pCi/L of radon and the charcoal used to remove the radon has an unimaginable amount of surface area.

Great info. Thanks for all the replies.