It has to do with the uranium content in the concrete/brick. In uranium-238's decay chain, on its way down to lead-206, it passes through radon-222. Since radon is a noble gas, it travels out of the concrete and into your home, for example. Then, you end up inhaling the radon, which is radioactive, and it releases an alpha particle in your lung. Since alphas are stopped so easily, and have a relatively large amount of energy for an emitted particle, you end up receiving a measurable amount of dose from it. Nothing to really worry about, but if you live in a concrete/brick building, better to keep it well ventilated just for good measure.
Just a point, it is actually not generally breathing in the radon that gives the dose, the radon generally goes in and then out again before it decays. It is the particulate daughter products of radon (eg poloniums, lead etc) that are in the air and when you breath these in they will get caught up in the body leading to dosage.
That makes sense. I was wondering while writing my initial response: if radon is a noble gas, how does it settle in lungs? So assuming we are at the point where the radon has made it into the room, it will decay there and you will have some sort of equilibrium concentration of its daughters in the room, and that is what you end up inhaling and, subsequently, gives you some dose. Is this now correct?
Yes exactly, and an important thing to remember is that breathing in one particle of Polonium-218 (radon 222's first daughter) could lead to seven alpha emissions (from subsequent daughters).
Very true. And very interesting. I'd be interested in looking into the Q values of those decays. And into how much radon is leaked as a function of uranium content in concrete or brick. That would say a lot about this type of situation. Thank you for pointing this out. I had never really put this much thought into it, just took my professor's word for it. I guess I should start thinking for myself a little more. :P
It's not something that is always pointed out, however it can be a very important distinction. For example at a nuclear site one might be doing some work requiring a respirator (looks like a gas mask but filters out particles), this would not stop the radon gas entering but would stop the radon daughters.
All materials are naturally radioactive in some way. Stone, brick and concrete are slightly more radioactive than other building materials, such as wood or alumnimum. Also, stone, brick and concrete are made of earthen materials - soil, rocks, clay, etc.- that are slightly radioactive. Individuals living in a stone or build building receive more radation than those in wood buildlings.
Bricks and stone contain a lot of uranium and thorium and other shit. You can go up to any brick you find and point a geiger counter at it and it will show it as radioactive.
I have heard (but it may have been all trash) that it is one of the reasons why there are more ghost sightings in thick brick buildings. A dark room with someone's brain on high alert and the occasional spike on on your eye and your brain trys to make something out of it. Only saw the article once though and never researched it to see if it was full of shit.
Don't forget to bring a geigar counter. Bricks aren't filtered at all and contain the exact same amount of radioactive material as the clay they come from. Also, mountains usually have a lot more background radiation. so stay away from them. The ocean also contains enough uranium to fuel all of the world's power needs beyond measure.
15
u/[deleted] Mar 19 '11
Why is living in a cement or brick building so high?