PlanetGeo: The Geology Podcast
PlanetGeo: The Geology Podcast
Elemental Geology 1 - Radon, the Unwelcome Houseguest (ReRelease)
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Welcome to Planet Geo, the podcast where we talk about our amazing planet, how it works, and why it matters to you. Well, hey there, listener. It is just us today. Chris is off, I'm sure, getting into trouble somewhere. So it's just you and me. We at Planet Geo are still on a break, and we're about to finish off season two by re-releasing several of our episodes on the geology of critical elements. This is one of my favorite themes. And uh so Chris isn't here to defend himself. I can tell you that he hasn't quite seen the vision yet, but we'll get him there. Don't worry. I love talking about this type of stuff, and so what we're gonna do today is we are gonna re-release our episode talking about the geology of radon, which is an element that we should all think about and uh and maybe worry about. And we're gonna re-release several episodes in the same theme, and then we are gonna end this re-release sequence with a new episode on the geology of neodymium, one of my favorite elements out there. So look forward to that. One last thing, please check out our Camp Geo Conversational textbook. The link is the first link in the show notes, and you can actually also check out a rock shop that my wife and I run. We run it through Etsy, and we have a variety of bookends and coasters on there that you can purchase. We've been running this for about three years now, and you know, it's really what I like to work on. When I have some free time or I just need to escape the family for a few hours, like uh has happened in the last couple days. You can search JRR Stonework on Etsy, or you can click on the link in the show notes and use the promo code PlanetGeo10 for a 10% discount just for being a listener. As always, let us know if you have thoughts or questions. We are planetgeocast at gmail.com. Follow us on all the socials at Planet Geocast and visit our website, planetgeocast.com. Hope you enjoy the episode.
SPEAKER_00You like it when I start recording, then I start doing this.
SPEAKER_01Yeah. So that's what I'll do.
SPEAKER_00It's the best. Hey, Jesse Remink.
SPEAKER_01Hey, Christopher Mois. Oh, he's got the sexy voice on today. Wow. Thank you for calling. What can I do for you? That is a voice for radio right there. I got the face to go along with it. I'm good. Oh man. Let's go. Let's go, Chris. You've got an interesting shirt on today. All I can see is beards. It's in the top half. A t-shirt. What's going on there? What do we got?
SPEAKER_00Let me let me sit up a little bit straighter. And you see.
SPEAKER_01Oh, beards brewery. Beards brewery. Oh, it's a brewery.
SPEAKER_00With a hop leaf, with a hop cone coming down as the beard. You know, and it kind of like you it fits my beard, right? Because it's kind of cone-shaped, you know, and I got that triangular look going on. You really do.
SPEAKER_01I was gonna mention it. Your beard is looking particularly flush today. The top of your head less so, but the you know, the bottom part of your face is pretty flush with hair.
SPEAKER_00Yeah, I know, I I know. I I do need to uh it's getting a little out of control. I gotta take care of it. It's looking good though. Uh you know, it's good. Yeah, thanks. I'm I'm proud to be doing this podcast with you. Well, you know, uh you I think if you would try to grow facial hair, it would look you'd look like a teen wolf, I think. Yeah, you know, you'd be splotchy.
SPEAKER_01Totally teen wolf. I cannot grow facial hair for for shit. I mean, it looks real bad. One time I grew, you know, Tessa's like, oh, you know, don't clean shave because a little bit of uh you know, gruff is it's man style. But then she's like, but you you have to keep it trimmed. Like you have to keep it really tight because it looks pretty grim.
SPEAKER_00However, nobody can grow a disgusting neard like you. That's true. Oh my gosh. You can grow a neard like none other. Yep. Award winning, I think. It is award winning. Hey, let's uh let's get into this. You ready? Let's do it, man. This isn't I I'm excited. Are you excited? I'm always excited. So that's kind of a dumb question.
SPEAKER_01So fair point. Fair point.
SPEAKER_00I'm ready to go. Well heck yeah. This was your idea.
SPEAKER_01Well, yeah, in part because when did you guys buy your house that you're living in now? Have you been there a decade? Uh almost, almost 10 years. Yep. Okay. So Tess and I just bought a house in uh in Pennsylvania. And because of the crazy housing market, we kind of had to waive inspections. I mean, we looked at the house and walked through it and it looked in pretty good shape. So we are a little bit comfortable waving inspections. But radon is something that often gets inspected if you don't have a radon system in your house, which ours actually has. So and we're gonna talk, it's like fundamentally linked to geoscience.
SPEAKER_00What you have a radon system. What does that mean?
SPEAKER_01Like what do you Well, it's just like uh uh the radon pipes that that sort of vent underneath of the the floor. So it's just a a vent system basically that gets rid of radon. Do I have one of those? You might. I don't know. Some some houses do, some get installed, they're relatively simple, but we'll get to that, like how to to sort of get rid of them. And I can talk about what mine actually look like in the in the I feel like that's something I should know, but I I really have no idea. Well, so we're gonna talk about radon because this is like geoscience. We get to cover a lot of cool geoscience stuff here with radon.
SPEAKER_00Absolutely. And you know, it is important. There are billboards you see, like have you had your home tested, and there's a phone number that you can call and have people come out and do it. I've seen those before. And one of the main reasons is because it is radioactive and it radon is a gas, and so it is, isn't it? I think this is true. It's the second leading cause of lung cancer behind smoking.
SPEAKER_01Exactly. If you're a non-smoker, this is the number one cause of lung cancer in in the US at least.
SPEAKER_00Well, hold on. I think uh let's uh let's give a little bit of a prelude to what we're gonna do. So we've kind of have this chunked up into three sections. We need to get into radioactive decay and how that works. We've touched on it before in previous episodes. We're gonna do it again in this context. So that's the first chunk. Then we're gonna talk about the geology of radon and how it moves and how all that happens. And then the last section today is gonna be all right, well, it's in your house now. What? What do you do?
SPEAKER_01And Chris, this is just like uh, this is just such a cool story and so directly relevant. Like, you know, it's in our houses. You can get your radon problem in your house fixed for a relatively inexpensive amount, you know, up to a thousand, maybe, maybe thirteen hundred bucks or something like that. It's not that expensive, but it's just such a cool story. It's a cool intersection between geology, chemistry, groundwater, rocks, and our everyday lives. It's just really, really interesting, I think. So, um, so you know, you laid it out perfectly. We're gonna work through those three things and and get to the point of the story because it's really cool.
SPEAKER_00One I agree with you 100%. It's an awesome story. Um, and I to me personally, I love intersections. I love it when science comes together where you have all these multidisciplines. I I think that's actually it's one of the most attractive things to me about geology, is it involves all kinds of intersections all the time. But this story, we have to get into some technical stuff, we have to get into some numbers, and like just I'm just telling the listener, bear with us, please, because it does go somewhere in a cool place, and we have to do this before we get to that, and it's worth it.
SPEAKER_01It's true, and we are gonna cover some numbers, and uh, I love the geochemistry side. We're gonna get a little bit into the weeds with the geochemistry, which is fun, but you're right, it you gotta bear with it.
SPEAKER_00You know, but the reason why you and I are having this discussion is we originally recorded it and my wife listened to it. We're listening back to this episode, my wife and I, and she fell asleep. And I'm like, never a good scientist. What the hell, Jen? What are you what are you doing? And she's like, Well, you kind of lost me with all the numbers, and not really that science-y, and you know, she's she's getting yeah, she's doing her thing. And I'm like, but this is a really like this is why this is important. And I kind of explained to her, she's like, Well, why don't you just lead with that? That would have been like do that, you know. So here we are, you and I sitting here thinking, wait a minute, this is I think a really good episode, and we just don't want to lose people on the front end because we got to cover some science stuff, but it is a science podcast, right?
SPEAKER_01That's right. So, Jenny, don't fall asleep. If you're like Jenny, don't fall asleep. Stick with us. We'll get there. It we'll get to the end of the story, and it's just a really, really cool tale. We have to get into the weeds of chemistry to start out with.
SPEAKER_00That's right. Get your head out of your Jenny.
SPEAKER_01So radon is an element, and its chemical symbol is Rn. That's you know, the the periodic table has all these symbols. RN is radon, and it's a noble gas. What does that mean? Explain that real quick. Yeah, noble gas is, you know, they're on the far right side of the periodic table. They have a full electron shell, an outer electron shell. So they don't bond with anything really. So they like to exist in the gas state.
SPEAKER_00Right, they're very stable. When something is a noble gas, it's very non-reactive and it's very stable. Now, we say that from the standpoint of a full, like, you know, all of its energy levels are full of electrons. However, we're gonna go into now, well, why is it radioactive then if it's stable? Now we got to talk about inside the nucleus. So we're really kind of talking about two different things.
SPEAKER_01Yeah, that's a great point, Chris. Yeah, absolutely, great point. So the electrons and the outer outer shells that determines chemistry, chemical reactivity. We're talking about the nuclear physics and the in the what happens in the nucleus is whether it breaks down or not.
SPEAKER_00And radon is sorry, nuclear chemistry is what you're talking about when you dive into like radioactive decay. So these are changes that happen inside the nucleus. And so let's get into real quick the what makes certain because they're not all elements are radioactive, only certain ones that you know, you look at your parent table and only a few of them are radioactive. And what all that means is that the nucleus of that atom is unstable, and so it's it's gonna spontaneously change to be it's gonna do something to become more stable. Not necessarily like stable, just more stable than it was.
SPEAKER_01That's right. And the way to think about this, a good analogy is okay, primer, the nucleus of an atom is the really compact thing in the center that holds all the mass. It has protons and neutrons in it. Those protons and neutrons, you can kind of think of these things as they're vibrating. They're little springs, all of them are kind of bound to each other and they're all kind of vibrating, right? So they're kind of shifting around. You have this mass of 222 protons and neutrons, they're all vibrating together. Now, every once in a while, at a random instant, half of them will vibrate in one direction to the right, the other half will vibrate to the left, and the atom will kind of split apart. That's just an example of sort of how this happens. These things are a vibrating mass, and randomly some of them will break off because they all vibrated in one direction, and then they they sort of lose stability. So that's kind of how this happens. And it's a sort of a very fast process that is losing mass from the nucleus. So we are creating two particles from one bigger one.
SPEAKER_00So, what I'd like to do, I think, before we get into like how this actually happens, let's talk a little bit about the way that radioactive decay happens. The, you know, what happens in the nucleus. You know, let's keep this as as simple as we can. But there are three basic modes of decay. And we say that decay, we we're just talking about how the nucleus is going to change. And when that happens, it's it's called decay. The first one, I think it's the most common in terms of going to radon anyway, is called alpha decay. So what this involves is you have an atom that is unstable and it changes by emitting an alpha particle. We call that alpha decay. And an alpha particle is just simply it's it's one particle that is made up of two protons and two neutrons, which is essentially the nucleus of a helium atom. Like if you take then, let's say uranium-238. When we call it uranium-238, it's atomic number 92, but it has a mass of 238. And the rest of the mass, so you have 92 protons, the rest of it is made up of neutrons. Okay. If you take uranium-238, it's an unstable atom and it spontaneously just changes. It emits that particle. Okay. Two protons and two neutrons, a helium atom. And so the new particle is gonna have a mass minus what it lost. And it lost two protons and two neutrons, which means it's lost a mass of four units, four mass units. Okay. And now you have 90 protons, which is the identity of the element. And so now you have instead of uranium, you have thorium 234. So we started with uranium-238. Now we have thorium-234, and that's also going to be radioactive, it's unstable, and it will change too.
SPEAKER_01Absolutely. Uh, you know, this is uh this is the key point, right? Is that these things are breaking down. And actually, the interesting thing about radon is it is not only itself radioactive, meaning it is unstable and it breaks down, and that's why it's damaging to us, but it also is the product of decay. So you talked about 238 uranium. Actually, 238 uranium, it starts to decay. And once it starts that process, once it kicks out a helium atom and becomes 234 thorium, it goes under this long chain of decay. It decays down for through a whole bunch of different elements all the way till it gets to 206 lead. In radon, the one that we most often worry about is 222 radon, it kind of sits right in the middle of that process. It is one, two, three, four, five, six steps from uranium to radon, and then another about 10 or 12 steps to get to lead at the end. So not only is radon radioactive, but it also is radiogenic. It is produced by radioactive decay, which is a really important part about the geology of it, which will give you.
SPEAKER_00That's right. The other common type of decay is called beta decay. And what beta decay is, is when the nucleus of an atom emits a very high energy electron. Okay. Now, electrons essentially have no mass. I mean, it it's ridiculously small. So the mass of the new isotope, well, we call it the daughter isotope, that mass is going to be the same. But I lost an electron. Okay. Now, this is something that really is interesting to me, Jesse, because with my students, and I'm sure you, I I bet you, I bet you money. I don't you'll correct me if I'm wrong, but I bet you your students, it doesn't occur to them, wait a second. Beta decay, we teach this, they know about it, they know, but they learn about it in chemistry class, right? But they hardly ever ask the question, wait a second, there aren't any electrons in the nucleus. So how does this happen?
SPEAKER_01Where does the electron come from? Yeah, exactly. So where does it come from, Chris? Where does the electron come from?
SPEAKER_00Yeah, if you think about then what a neutron is. A neutron is a neutral particle, so it has no charge and it has a mass of one. Well, if you take a proton and an electron together and you know, just mash them together, you have something that has no charge and it has a mass of one. So a neutron is made up of those two subatomic particles. So when beta decay happens, think about this neutron vibrating and all of a sudden just kicks out this electron, the proton stays, right? So your atomic number will go up by one because now I have a proton that used to be a neutron, and I lost no mass. So that's how beta decay happens. And this is confusing when you're first getting exposed to this kind of thing because they're like, wait a second, the atomic number goes up, but I lost something, you know?
SPEAKER_01Yeah, it's it's very confusing. It's very confusing in this way.
SPEAKER_00But it's not if you understand what a neutron is.
SPEAKER_01And so there are two types of decay. Like you said, these are the dominant ones. There's a few other ones which are not important for most of the colours. Electron capture, and yeah, yeah, they're not super important. But both of these modes of decay occur from the path from uranium down to lead. And as we said, there's like 16 or 18 steps in that process. So both of these are occurring in this way, and radon sits right in the middle of it. So ultimately, Chris, what is the source of radon that makes it maybe into your basement? Like, where is that coming from?
SPEAKER_00Ultimately, I'm so glad you asked this question. Ultimately, it comes from uranium 238. That is the source of radon 222. So can I do this, Jesse? I'm just just bear with me a minute.
SPEAKER_01Oh man, okay. I I'm I feel like I'm always bearing with you, you know. I know. So I know. Uh what I'll do it for one more minute and then we're done.
SPEAKER_00But but hold on. Before we do this, though, we have to also refresh one thing too. What is the half-life? Okay. Oh, yeah. Each radioactive element has its own half-life. And all that means is the half-life is the time it takes for half of the atoms that are present to decay.
SPEAKER_01Let me try the analogy. Let me see if I get your analogy right because it's a great one. It's the is this the shoebox analogy? Is this where you're gonna go? Yep. Okay, I used it in class the other day, and I want to make sure I get it right here. So basically, you take, let me go with it. You take your shoebox, right? Chris, Crisple Ice is grabbing his shoebox. Maybe he's got some new, you know, ASICs that he's about to rock out in the retirement home.
SPEAKER_00I'm an old man now. I've gone to Hoka.
unknownHoka.
SPEAKER_01That's great. That's really good. Uh, that's a good visual right there. So you take your Hoka shoebox, you fill it up with a whole bunch of pennies, and you shake it for a known amount of pennies.
SPEAKER_00Put a hundred pennies in it or put fifty in it, put it whatever. It's got to be a known amount.
SPEAKER_01Yep. Let's do a hundred. I like a hundred. That's nice and even shake it up for five shakes, five or maybe five seconds, ten seconds. Then you open it up and you take out all the pennies that have tails facing up. That's what I always would go with with the heads or tails thing. I'd always go with tails. So we're gonna take out the tails. How many are gonna be left? Half. Round about 50, right? Okay, is that the analogy? That's one half-life. And then we put the shoebox back on, shake it up for another five seconds, open it up. You only have 25 left after you take out all the ones with tails in it. So because it's this probabilistic phenomenon, radioactive decay.
SPEAKER_00Right. And the important part about this is that nothing changes the half-life of an element. Okay, you can't like heat it up or squeeze it a lot with under immense pressure. The half-life is well established. So each element has its own half-life, right? The time it takes for half of the atoms that are present to decay. So uranium-238 decays by alpha decay into thorium-234. And it's got a half-life of 4.5 billion years. That first decay step, yeah. Yes. Thorium-234 will decay by beta decay, so it's going to emit an electron from the nucleus, and it has a half-life of only 24.1 days. And that will change by thorium-234 changes into protactinium 234. No change in mask. All we lost is an electron, a very high energy electron, right? So protactinium 234 changes also by beta decay back into uranium 234. Back up to atomic number 92. So I have two more protons that I didn't have before because I went through two betas in a in a row. Now protactinium has a half-life of 1.17 minutes. Okay. So uranium-234 decays by alpha into thorium 230. Half-life, 240,000 years. So we're back up to a long time now. We're back to a long half-life.
SPEAKER_01Yeah. Absolutely.
SPEAKER_00Thorium 230 goes alpha decay to radium 226. Now we're getting close, okay? Thorium 230 has a half-life of 77,000 years. And then here we go. The final step, radium 226, alpha decay, changes into radon 222. And radium 226 has a half-life of 1600 years, 1,600 years. Now we have radon 222 in your home. Okay, that's what we're talking about. It's a gas, and we'll talk about why that's important. And it's also important to note that that's also going to change down into other things all the way down to lead 206, right? But it has a half-life of 3.8 days. So it doesn't stay long. That's how you go. You asked me, and I had to do this, say the ultimate source, it starts with uranium-238.
SPEAKER_01It's got all these steps in between, right? And so there's two important points here that we're sort of leading into. The first is if you've listened to Planet Geo or if you're familiar with what enriched uranium is, there's multiple types of uranium. Chris, you've been talking about two hundred thirty eight uranium, which is the key one for uh producing radon, right? But there's two hundred thirty five uranium as well.
SPEAKER_00Why aren't we concerned about that?
SPEAKER_01It's a great question. Why are we not concerned about the radon? Because radon is in the decay chain of 235 uranium. Uranium-235 starts to decay. It breaks down all the way to lead. Somewhere in the middle is radon. The reason we don't care about it is because there's very little uranium-235 in the world today. Out of 138 atoms of uranium that you find, only one of them is going to be 235 uranium. The other 137 are going to be uranium-238. So the vast majority of uranium out there is 238 uranium. Now, the other reason we don't care about the 235 decay chain is because the half-life of radon in the 235 version of it, the 235 uranium flavor, has a half-life of 55 seconds. That's very short. So that is going to decay away very quickly. It's there and it's gone. It's there and it's gone, right? The half-life of 222 radon, which is the one in the 238 decay chain, has a half-life of, as you said, 3.8 days. Now that's long enough to matter for us. And why does this matter? Like why do we care about the length of the half-life here for this radon step in the decay?
SPEAKER_00Because it's long it's there long enough for us to go down and inhale it because it's a gas. We can we can ingest this into our system. So we have that. That's not good because it's radioactive. But then it also changes, it continues to change, you know, and and it's only a gas in radon. That's the only time that this whole decay series exists in the gas form.
SPEAKER_01Okay, so now we're kind of shifting into the second part of this thing, is the geology of radon. Did you know that? Are we ready to do that? Are we ready to do that? I think we are, because we're right, we're right on the cusp of it, I think. Here you nailed it. This is the only step in this whole 16 or 17 step decay chain where this uranium-238 atom has turned into a gas phase. So radon is the gas, which means it can move. All those other ones, thorium, radium, those don't move. Those elements are bound in whatever mineral or clay that the uranium existed in originally. As soon as it hits radon, it doesn't stick to anything. It does not chemically react. So it can move, it can flow in airspace, and that's how it gets into your basement, basically. So we kind of gotta step back and talk about like where uranium occurs in in geoscience, right? Because like, okay, you know, radon's coming from uranium, but why is the uranium there? What's it existing in? Like, where does this start? How does uranium behave?
SPEAKER_00Yeah, so now we get into the geology of this podcast. Okay, here we go. Here we go. So look, you're the expert on this, hands down. I bow to you on this, okay? But I'll I'll give it a go and you can interrupt me. All right, but okay, uranium is fairly common in certain kinds of rocks on in the continental crust. Okay, it's common in rocks like granite, it's common in certain sedimentary rocks, and it's therefore when these rocks break down, then they form soil. Chemically, they'll break down, mechanically they'll break down, and it forms soil. What our homes are sitting in and on. Okay. All right.
SPEAKER_01How did I do? I mean, it's perfect. Yeah, I think that's a really important point because you know, radon is coming out of the soil. Most homes are built in soil, they're not built in bedrock or anything like that, right? Like our basements, if you have a basement, it's sitting in soil of some kind. That soil comes from weathering of a rock, it's breaking down a rock. And there's uranium in the rock, and therefore there's uranium in the soil, right? And the other aspect about soil is that it provides all these little air spaces so that when radon is formed, that radon can go into those air spaces and start to move around quite quickly. And so I think we need to touch on a couple of key geoscience terms here with regard to sediments, which is porosity and permeability, Chris. Do you think it's time to talk about that now?
SPEAKER_00Yeah, I do, because those things help control the mobility of radon. When it once it hits that gas form, it can move. So if you are talking about a soil or a sedimentary rock that has a high porosity, what we're talking about simply is the spaces between the grains. Like you're, you know, your skin is very porous. A sponge is very porous, okay? It's the spaces between the the other pieces, the solid pieces, right? It's the air, okay?
SPEAKER_01And we talk about porosity in uh percent. So it's the percent of stuff that's not a mineral, basically. It's the percent air.
SPEAKER_00I can I can maybe give an analogy with this. If you take like a five-gallon bucket of loose beach sand and fill it all the way up to the tippy top, right? All right, well, what's the porosity of that? Well, you can measure the porosity by how much water can you pour into that bucket without changing the volume.
SPEAKER_01Oh, that's a good one. Without the water spilling out of the top of the bucket. That's a good one.
SPEAKER_00Yeah, with loose sand, you pour the water in and you can, with a five-gallon bucket full to the tippy top, you can put in about two and a half gallons of water. So that water is pushing out the air. You know, you'll see it start to bubble as you pour water in. And what that means then is sand has a 50%-ish porosity. Okay, 50% of the sand is just airspace. Okay. Well, if that's what you have, you got a soil that has a high porosity, uh, a lot of air in between the grains. That means then that radon can move through that easily, right? So high porosity favors mobile radon.
SPEAKER_01Yeah, and a different but related term is permeability, which is the ability of stuff to flow through there. So it's the interconnectedness of all those pores. So you could imagine a scenario, Chris, with your let's go back to your bucket, sand in the bucket analogy, because that's a great one. That sand, if you just pour a bunch of sand grains in there and fill it up, that is very permeable because the water can flow all the way to the bottom of that bucket really easily. And if you put a screen on the sand and tip the bucket over, the water's gonna flow out of there really easily. It's permeable. The water can flow. If instead you take you you fill up that bucket with a rock that has a big hole in the middle, a single hole, that is a solid rock with just one big hole, you can still have 50% porosity. There can be one big pour that is two and a half gallons sitting right in the middle, and you can fill that with water and tip it upside down, and it's never gonna flow out of that rock enclosure. So think of like a big bubble of water locked in a rock capsule. It's not going anywhere. Pour cement in there. Maybe let's make it a cement analogy, right?
SPEAKER_00Like I had no idea where you were going with that analogy, by the way. Did it does it make sense or not? Was this a terrible analogy? Let me give another go at it and see what you like best. Can I do that?
SPEAKER_01Yeah.
SPEAKER_00You sure? I don't want to hurt your like sensitive soul here. I'm not feeling that sensitive this week. So I think Okay, good deal. Take another drink of wine and sit back and listen. Okay, I see you. I see you. Let's see how it's done. Watch the master at work. I don't have anything. I don't know what's going on. This is I'm breaking a rule right now. I'm not, I don't have a beer while we're recording. I'm just gonna sit back here and watch the master at work, Chris. That's what I'm gonna do. Here we go. Five gallon bucket, dumped all the water in it I can. Okay. And you just got done running a half marathon. You are exhausted, you are you're dehydrated and you are thirsty. Okay. But you got that five-gallon bucket sitting right in front of you with sand and water in it. I give you a straw, say have at it. You stab the straw in that sand, and you just you can drink it, no problem. No problem at all. Okay. Now, next week, same thing, run a half marathon. I come chuckling up to you, you know, moseying on up, and I say, Hey Jesse, how you doing? And you're like, Oh man, I'm so thirsty. And I hand you a lump of clay. Okay, now this clay has all the water in it. You go, Well, it's got gallons of water in the clay because it's got a really high porosity. I hand you the lump of clay and I hand you a straw. You stab the straw into the clay and you go like that, nothing's coming out. Because clay is really, really porous, but it is impermeable. It will not let the water go. Okay. How'd that do? Uh, what do you think?
SPEAKER_01That's a better one. Uh um, yep, I've learned a lesson here today. That's a better one. Please never never disagree with Chris Bullheis, is the lesson I'm taking here.
SPEAKER_00Okay. All right. Okay. So we we we've got hold on now, but hold on. So if you take a rock that is really porous and really permeable, radon can move through that easily. Okay. Totally. So it can move through the soil, it can move through the sedimentary rock, and it can move then into your home very easily. Okay, that's the moral of the story, right? If you have rock that's really porous or soil that's really porous but impermeable, then it's gonna have a harder time seeping through that and getting into your house. So the geology is gonna help determine what happens in your home.
SPEAKER_01Yeah, so let's kind of come full circle here. We've got radon, it's uranium has 238 has decayed down to 222 radon. It's produced, it's a gas, it can move now. So we're talking about porosity and permeability because that radon has to move from the soil into your home in some way. And there's many ways for it to get into the home, but there's a time aspect to this. It does not have an infinite amount of time to move because remember, we only have 3.8 days. That's the half-life. So most of the radon that's that's produced today will be gone within about uh 16 days or so. Around about six half-lives is kind of what we think of for the time scale of going from 100 to zero, basically. So that radon has to move quickly. So, what it means is the source, the uranium source, has to be pretty close to your house if the radon's going to make it into the basement, or it has to be able to move really fast from further away. And so radon's moving through the pores and the permeable rock layers and gets into your basement. But like what other factors contribute to how fast radon moves into your house and therefore how far away from the uranium source matters.
SPEAKER_00The other big thing is water. So if you have water that's sitting in the pore space, then water's gonna slow down the mobility of the radon.
unknownOkay.
SPEAKER_00So it really, I mean, it's complicated, and we're keep we're trying our best here to keep this like simplified a little bit. Think about it three variables in radon mobility porosity, gotta be porous, permeable, it has to be, you know, allow it to flow through it, and dry. Not a lot of water in the pore space. If you have that, then you have the potential for very mobile radon gas. Okay, now can I uh one thing what makes the radon so mob is actually the decay process, and I think this is so cool and it's worth highlighting because I think it's something that everybody can relate to. All right, analogy A high-powered rifle has a recoil on it, right? You pull the trigger and it recoils into back into your shoulder. Okay, the bullet is going the opposite direction. Well, that's exactly what happens with radon 222. When it becomes unstable and it ejects this alpha particle, that's the bullet. When the radium 226 decays into radon 222, it does so by emitting very forcefully an alpha particle.
SPEAKER_01Which is the bullet in this analogy, right?
SPEAKER_00That's right. And the radon 222 then is projected the opposite direction, and that's how it moves. That's isn't that cool? Like I just like that's it's cool.
SPEAKER_01And so, you know, there are people who model these things, who model these processes, and actually we'll create like a chemical model of uh the bonding environment in an atom. So, you know, imagine a uranium atom sitting there and it's bonded to oxygens and silica atoms. When that thing undergoes alpha recoil, it blows a massive hole in the mineral. I mean, relative to the size of the uranium atom, like you know, many, many like 10 or 20 bonds radius are broken in this crystal lattice. So basically, this uranium decays to thorium and it breaks a big hole in it. Then that thorium goes to protactinium, uranium, uranium again decays to thorium, it blows another hole in it. It goes from thorium to radium, blows another hole, radium to radon. By the time we get to radon, there's one, two, three, four alpha decays. You have uh fired a rifle into your shoulder four times, yeah, it could get a little bit sore at that point, right? Like the mineral structure is broken down. And why why do we care about the structure, Chris? What do you mean?
SPEAKER_00What what do what do you mean?
SPEAKER_01Radon needs a broken mineral to be able to get out of it. If uranium's locked in a mineral, a crystal lattice, it can't get out. So it needs like an interconnected pathway of broken crystal to actually get out of the crystal and into this pore space in the rock. So there's this rock structure, rock scale, and mineral scale, and atomic scale processes are all linked together in creating radon in your home.
SPEAKER_00It's very recoil effect then of the decay process can propel the radon 222 that's now a very mobile gas that can propel it through a porous, permeable, and relatively dry soil structure or rock that that's existing there and therefore move into your home. One of the things, Jesse, this is one of the things I love about doing this podcast with you, is what you bring to the table is so different than uh the direction that I would have gone into. Like, you know, you've obviously read papers or you've been exposed to this process before where it's blasting a hole in the crystal structure. I'd never heard of that before. Like that's uh I learned that then just now with the rest of the listeners by talking to you.
SPEAKER_01Well, first of all, it's really fun. We both uh, you know, building the script is very fun because we we learn from each other, we take it very different pathways. It's very, very fun to do this. And sometimes we argue and sometimes we almost break up and then we get back together, and you know, it's all it's all very fun. But I I'll I'll uh I'll have to find this. I haven't seen it in a while, but there's a great animation that I think uh would be really useful for teaching teaching this kind of dictation.
SPEAKER_00I really want that animation. I'll send it to you. If you can find that, I want to use that because I'll use that in my classes for sure. Yeah, like I'm always looking for stuff like that.
SPEAKER_01So I think it's all right.
SPEAKER_00Well, we need to move on. Okay. So we talked about the mobility. I think we're good. I are you you you agree with that?
SPEAKER_01Like, or you know, how yeah, let's I think let's transition to the house now. Let's focus on like you know, the the actual getting it into your house, right? And this is something that astonished me. I didn't really know this. I mean, okay, many houses have foundations, old houses like the one we have, foundation is a little bit cracked. It provides an easy way for air from the soil to make it into your basement, right? But you got this basement that's this gap, this ship in the ocean.
SPEAKER_00Hold on, a lot of our listeners though don't have basements. Like that's kind of a Michigan thing, you know?
SPEAKER_01That's true. And we have a lot in Pennsylvania as well. So it doesn't matter if you have a basement or not, but basements tend to be high radon locations just because radon's 222 mass units, it's pretty dense, so it'll kind of sink down. But I didn't know that most houses, especially new houses, draw only well, less than 1% of their house air comes out of the soil. The rest is circulated through the atmosphere. In an old house with a cracked foundation, you can draw up to 20% of the air in your house from the soil. That astonished me.
SPEAKER_00I did not even for me. I'm amazed that my house, which is pretty well built, that it would draw 1%. Like that would surprise me that it would draw 1%. Now, my old house, I had a Michigan basement. Like I actually had parts of my basement that was dirt. I'm telling you right now, I should have had that home measured for radon. Like, I some of the problems that I have right now, like maybe my mental status is because of like I lived at that house for about 20 years. Uh I was sucking in some radon for sure. I guaranteed. Um that house is probably inhaling 50% of uh the air from the soil.
SPEAKER_01It's an amazing number, right? Like how much soil air you can get into your house. I agree. Uh it's 1% seems like a lot. And then you talk about 20%. Oh my God, that's amazing.
SPEAKER_00You know, like even if you don't have a basement, okay, you still have footings, you have a foundation that's dug into the soil. So either way, when a home is put in a place, a hole is dug, right? And especially this is compounded when you have a basement. All right. So you dig a hole and you build, you put the walls in and so on, you build the home, right? And then now you have this area that is what, two, three feet between your walls and the hole that's dug, they have to backfill it. Well, it never really fills in the way it was when you dug it out. You know, it's not gonna be as compact as so now you have really increased the porosity and permeability of all that area surrounding your crawl space or your basement.
SPEAKER_01That's a really good point.
SPEAKER_00Then now all of that uranium that is near the wall that you or the hole that you dug, when it's near that, now it has an avenue to travel through very porous and permeable, loose, unconsolidated fill. And now it's in your house.
SPEAKER_01That's a great point. And the last way that these get into your house, even if you don't have a basement, is through water. Actually, radon can be dissolved in water, and then when you bring your water into your house, when you agitate that water, it's a gas, so the gas is released. So showers, any kind of pumps, sinks, running water that is agitating the water, the radon can escape from the water.
SPEAKER_00However, this is usually gonna be from people that have wells. Good point. Where that's not like a municipal water supply that gets tested and treated and things like that. So which, like I have. So again, um, I've got a well, and uh, you know, that's a really interesting thing, though. When you, you know, so this water has the radon in it, and you agitate it by doing dishes and things like that. The radon now is in the air. Yeah. Sitting in your hot tub. That's true. Sitting in your hot tub.
SPEAKER_01You got that right. Um, you got that. So I I you know, this last part, I think now it's in our house, and you know, we we've kind of talked a little bit about why it's dangerous, but let's just talk. There's a little, a few sort of things to tidy up here about when radon gets into your house, right? First of all, it's heavy, it's 222 atomic mass units. Most of the air, most of the atmosphere is oxygen and nitrogen and carbon dioxide. These are all far lighter. So radon will sink, which means it can stagnate often in your basement. And so that's where people go to measure radon, and and that's where sort of the risk is, is the lower levels of your house typically, because that radon will kind of sink down in your house, and it's hard to get out, actually, because it's so heavy. So that's the point of it. The other aspect is that we've talked about this half-life thing. It's a short half-life. So if it gets into your house, first of all, it's not going anywhere. Second of all, it decays, and there's a whole bunch of decays that happen. Remember, radon is only one step down from uranium to lead. So there are between seven and ten additional steps of decay, of radioactive decay, and of those, some of them are alpha particles, before it becomes lead. And so basically, you know, once you have radon, you have a bunch of alpha decay going on, this really energetic process, and then it ends in lead, which is not a great element to have around and to have in your lungs. And so, you know, the main risk is inhaling the radon, and then it's in your lungs and it decays down, and then it's lead, and you got lead in your lungs. Um, so that's kind of the dangerous aspect of it. And this is why we need to get it.
SPEAKER_00Okay, so what do you do though? Like, do you is it just an air circulation uh solution?
SPEAKER_01Yeah, it's actually mostly not an air circulation solution. It's mostly a preventing it from getting into your house. So the the houses I've seen in in Pennsylvania and the house we have here has what's called a passive radon system. So you could basically what you need to do is you need to take a uh drill a pipe. You talked about Chris, that boundary, that backfill boundary between the soil and your foundation. What you do is you basically put an air pipe down in there that sucks out the air from the area around your foundation. And so all it is is taking that gas, that soil gas, that would normally get into your house, and it's just venting it up into the atmosphere. So that's all it is. And there's an active or passive system. Some of them have a fan attached to them, the active ones where it's actually pumping out the air. Ours is a passive system, and this is really kind of cool. All it does is just a pipe, a series of pipes that are, we have a basement, so it's a series of pipes running under our foundation that are taking the air out, and it's passive. There's a pipe that goes up to the roof, and whenever wind blows across that pipe, it creates low pressure and it sucks all that air out. And so any amount of wind is just sucking air out, it's it's kind of cleansing the air around our foundation of radar. Which is just a cool, very cool thing.
SPEAKER_00It is a very simple thing, but not if you didn't build the home with that in mind, which a lot of homes are not. What do you do then?
SPEAKER_01These pipes are not huge and you don't need to go all the way under the foundation. Usually they can just wrap it around the foundation on the sides. So it's it can I don't know the ex how expensive it is to get these installed. Um I think the because that like I said, the house we have um has it in place, had it in place already. But I think most modern homes will be built with this detection system or with this um radon prevention system in place. To get it installed, I'm not sure what the price is, but it's not ultra expensive. You know, something you need to get tested.
SPEAKER_00I'm curious how how did you know you have it?
SPEAKER_01You can see it in the walls outside. And often it's running in ours, it's running inside the basement. Um you can see some of the pipes running up.
SPEAKER_00Oh your basement's unfinished then?
SPEAKER_01Yeah, basement's unfinished. Yep. All right, gotcha. Okay. And there's a there's a pipe, you know, running along the side of the house, just a PVC pipe that goes up to the roof, and I'm like, I wonder what that is. Oh, it's a radon system. Okay, cool. But where I'm at Pennsylvania is a pretty high radon risk area in general. We have a lot of carbonate rocks, which are high in uranium, and so therefore the soils are high in uranium, and there's just high uranium background. Where you're at in Michigan, it's a little bit different. The soil isn't as high in uranium, but you have really dry soils. So I think that's why Michigan might be higher radon. Do you on that?
SPEAKER_00Um, so my situation is unique, and I think a lot of people are in the situation I'm in. Uh, we are in clay. Okay. And so I'm on top of a hill, but I'm I'm in clay. And so clay is impermeable, but it's very, very wet. So it it it has it has the water that both of these things act to slow it down. However, if there's a lot of uranium on that whole wall that was dug, then you have access for it to get into your house.
SPEAKER_01Um that's a good point.
SPEAKER_00There are a lot of people though in our area that are in sand. So we have these like you know, ancient dune and sandy, you know, kind of deltaic uh environments that homes are built in. And so they can have an increased problem because you know it has it's porous, it's really permeable, and it's relatively dry because sand has such great drainage.
SPEAKER_01Yeah, and radon's just flying around through sand, so it can just flow really quickly through it. So, you know, I I think it's important because this is a uh a geoscience topic that is immediately societally relevant, but also has health implications. I think we should point out, Chris, we'd be remiss if we didn't point out that places you can learn more and places you probably should learn more if you don't know uh about your home. In the US, at least, the Environmental Protection Agency, the EPA, and the United States Geological Survey, the USGS, have maps and really actually great guides that can help homeowners, but it's a very local problem. Like houses in the same neighborhood have very different radon risk factors, basically, because some older homes, you know, depending on how your quality of your foundation, it really a lot of things matter. So getting your own specific home tested is a pretty important thing. Most other countries, I know Canada has them, uh Germany, the the same sort of governmental agencies will have radon resources that that people should look into.
SPEAKER_00We'll put a couple links in the show notes, like the EPA um radon map. We'll put that in the show notes and so on. So if you're interested, check it out.
SPEAKER_01It's kind of fun to look at the radon risk map too of the of the United States.
SPEAKER_00These they're but you have still have to be careful of it though.
SPEAKER_01That's true.
SPEAKER_00By like you said, I mean, you can have a neighborhood that's you know, these you're in close proximity to the people and and very, very different radon levels in the low levels of the house.
SPEAKER_01That's a really good point. Yeah, it's is it was sort of fun. I I I looked at the US map, and you know, you see the big color plot splotches pasted over the map, and then you zoom in on Pennsylvania, which I did, and uh, you know, it it gets more detailed, definitely. It gets more nuanced for sure at the county level and at the township level. So it it's it's interesting to look at. Um yeah. So I thought this was fun, Chris. And I think we should, you know, these types of things where geoscience, there's an interesting geoscience story behind a really important process that everybody should sort of be aware of.
SPEAKER_00That's right. That's right. That's what this is all about. Our amazing planet, how it all works.
SPEAKER_01I know, and how it impacts our everyday lives. It's so good. That's right.
SPEAKER_00So now you had a good idea. Uh it took me a little bit, but once I started digging into it, I was sold. This was fun. I like learning about it.
SPEAKER_01We almost break up over this episode. So we didn't.
SPEAKER_00No.
SPEAKER_01That's true. We're we're becoming more cleaved. That's right. All right, man. With that, I think that's a wrap. If you enjoy Planet Geo, share with your friends. That's by far the most important. Give us a like, subscribe, those matter for the algorithm, and follow us on all the social medias. We are at Planet GeoCast. That's right. Cheers. Cheers. See you next week. See ya.