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Uranium decays to thorium decays to radium decays to radon, and so on. So any or that contains uranium will contain this huge suite of decay products as well.

What's especially interesting to me about tobacco is that it selectively removes polonium from all the others and puts it in the hapless smoker.

Most commenters here are referring to the decay of radon in air, but it also occurs in solids and water, like rocks and groundwater. In radiological risk assessment for radioactive waste, we are interested in what happens to the radon parent, radium, when it decays to radon.

A radium atom will generally exist as part of a crystal matrix or as a radical or compound dissolved in groundwater, and when it decays to radon its physical form depends on whether the recoil from the emitted alpha is strong enough to knock the newly formed radon atom out of the crystal matrix or out of the water into the air or from one crystal into another or into the water. The probability of radon escaping the solid phase and going into a fluid phase, being air or water, is called the escape to production ratio, Nielsen and Sundquist. I study this as part of radiological risk assessment because once the new atom is in air or water it is available for transport. If the radon does not escape the crystal, it will soon decay to polonium and other progeny, and likely stay put. Note also that radon has an affinity for water as well, so in balance, some radon will be in the air and some in the water.

That's interesting. I always wondered where the Polonium-210 came from. I have a radioactive apatite from Brazil. In this case it contains radioactive thorium, but yes apatite (phosphate ore) can also contain uranium.

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How many grains of sand do you need before it can be called a heap?

Radon Daughters stick to dust at ground level and that dust is carried into the higher atmosphere by rising air currents, they can rain out when there's heavy rain, thunderstorms particularly, a phenomena called Radon Washout.

It was discovered by accident in the 1960s. A nuclear worker walked though puddles in a car park on the way to work, and he set off the alarms as he arrived, since that's backwards they were intrigued, and they discovered that atmospheric dust is coated with radon daughters which can get concentrated in electrically charged thunderstorms, and rain out as Radon Washout.

Radon Washout can sometimes be intensely radioactive, and there's a paper that estimated that a few percent of skin cancers might be linked to Radon Washout, beta radiation from Lead-214 and Bismuth-214 decay is able to penetrate the outer layers of the skin and deposit a radiation dose to living skin cells, a risk increased for people who work outdoors. This might be speculative, nevertheless, it illustrates just how radioactive rain can be sometimes be when weather conditions are just right.

I measured it myself a few times. Got readings up to 2 microsieverts per hour, nothing spectacular.

Styro, B.I. and Stelingis, K.I., 1978. On the value of flow of long-lived radon-222 decay products into atmosphere with the dust of natural and anthropogenic origin. In Chemical and radioactive pollution of the atmosphere and hydrosphere. V. 4.

Edit: Also, >90% of indoor radon daughters are bound to dust, very little is unbound, free floating.

Commercial tobacco is also fertilized with mined phosphate fertilizers that are naturally Rick in uranium decay series elements, including Po-210. It also turns out that the tobacco plant has an unusually high affinity (uptake factor) for polonium, and the leaves become enriched in polonium. Smoking those leaves is the most effective exposure pathway: inhalation. Put all that together and voilà: cancer.

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>How do you even clean that out and make the space usable / liveable after taking radon mitigation steps?

If you've taken radon mitigation steps (such as barriers against radon infiltration from the ground, overpressure in the building or increased basement ventilation from non-radon air sources) then the remaining already deposited decay products on surfaces in the basement should be negligible. Just vacuum the place.

Air is fairly diffuse, as in there aren't nearly as many atoms per unit volume as with a liquid, so the atom will stay suspended until it encounters another element or compound with which it can react chemically and has an interaction with that other element/compound of a long enough duration that the interaction can proceed. Smacking into an O2 molecule "might" result in the formation of PbO but not if the collision is too forceful, too weak, or not adequately direct. Eventually, over time, thermodynamics say that the metallic lead in air will undergo an oxidation-reduction reaction and make some sort of base salt such as lead carbonate or lead oxide. However, it does take some time for that to happen on a statistical basis (never goes to total completion, really).

Even then, though, the new compound will tend to stay suspended until it absorbs onto some larger solid or dissolves into some larger liquid mass (like droplets in a cloud). It will then go wherever that larger mass ends up going.

If air is still (no movement at all), there will be a slow downward migration because of density differences, but even the slightest air movement will be enough to keep the atoms or tinier particulates in suspension.

Mostly though, the atom will bounce around in the gas, as part of the gas phase, until it gets lucky and reacts with some other participant in the chaotic dance, making a new molecule.

Even metallic lead has a vapor pressure, the presence of some atoms that will leave the solid and enter the air just by random energy pulses, so the drive to "rain" out of the air just by density isn't all that powerful. That is, in a closed space, if you leave a bar of lead out on a tabletop, some of that lead will escape the solid and enter the air. Not a lot because lead isn't all that volatile, but you cannot prevent all loss at the interface (surface of contact between air and solid).

I don't know what the average residence time (median duration that the atom would exist in suspension before descending to the ground) of a lead atom in air would be. Not likely a value measured in seconds or minutes. Even household dust has mean residence times longer than that, and that stuff is destined to fall fairly rapidly by comparison to a lone atom, if only the air would stay still long enough.

I find that pretty interesting, but I imagine that especially the upper atmosphere, with high levels of ionizing radiation and radicals floating around, doesn't resemble inside of a jar, not to mention the distance the daughter nuclides must travel before deposition is vastly increased for atmospheric radon decay products.

If you've already taken radon mitigation steps, you're good. The big danger from radon is inhalation, you really don't want any radioactive decay to occur inside your body. The radioactive dust can likely be removed through simple cleaning activities, and isn't that dangerous if it remains outside your body. Radon's decay chain exclusively produces alpha and beta particles, which your skin can easily block.

Fuel enrichment was originally an extremely expensive service: Part of the advantage to the CANDU and RBMK designs was they didn't need it (CANDU still doesn't, modern RBMK does). Back then, uranium enrichment was primarily accomplished through an extremely energy-intensive process called 'gaseous diffusion' that required large facilities and infrastructure. Then the gas centrifuges arrived, and cut enrichment costs by an order of magnitude.

The last US gaseous diffusion plant was shut down in 2013, but it was uneconomic far prior (IIRC, it was kept around for DoE weapons purposes since that uranium can't be civilian-procured). Modern enrichment is relatively cheap now, which is part of the reason the nuclear industry is interested in boosting enrichment rates (which would have been prohibitively expensive originally).

There are billions per second over all, the individual lead atom isn't hitting an individual oxygen radical a billion times a second.

Having high radon levels in a basement area, a little above the recommended levels, shouldn't be a problem as you don't spend much time there, unlike a bedroom or living room.

Also, if you have a clothes drier in your basement and a Geiger Counter, a fun experiment involves measuring the radioactivity of the lint caught in the dust trap. It can sometimes be extraordinarily radioactive.

https://youtu.be/1s8wYJybizc

It doesn't work for me, as my clothes dryer is in a well ventilated room.

Also, the most effective way for society to reduce the risk of lung cancer from indoor radon exposure is to reduce rates of tobacco smoking.

Most people who get radon linked lung cancer are current and former smokers, as smoking reduces the lung's capacity to repair DNA damage caused by ionizing radiation. Smokers are almost 9 times more likely to develop radon linked lung cancer than never-smokers.

>The BEIR VI model also purports a significant synergism between radon exposure and smoking in lung cancer risk. On the basis of BEIR VI, the EPA estimates that, at a radon level of 4 pCi/L, the lifetime risk of radoninduced lung cancer death for never-smokers is 7 per 1000, compared with 62 per 1000 for ever-smokers.

Lantz, P.M., Mendez, D. and Philbert, M.A., 2013. Radon, smoking, and lung cancer: the need to refocus radon control policy. American journal of public health, 103(3), pp.443-447.

Wasn't it Ignalina you're thinking of?

Where did that value come from?

Assuming a straight line going through (0.6, 4.6) and (1.36, -4) we reach 1000K/(293K) = 3.41 at -21.65 which means 10^(-21.6) Pa. The extrapolation that far out will come with a large uncertainty of course.

Now I'm thinking about this room with 100ppm lead in the atmosphere, and how fast the neighborhood test scores are dropping.

So does that mean my basement with it's slight radon problem is entirely covered in radioactive particles? How do you even clean that out and make the space usable / liveable after taking radon mitigation steps?

FYI. have a radium dial compass sealed inside an air tight jar, safely stored in an unoccupied room. It's highly radioactive, back then Zinc sulfide phosphor wasn't particularly sensitive so they compensated by adding extra radium.

Anyway, the interior of the jar gets coated with radon daughter plate out:

https://imgur.com/XpibmUV

This is the decay I measured, due to Bismuth-214 and Lead-214 decay.

Anyways, the contamination stubbornly adhers to the glass. I tried rubbing it off with tissues, dampened with water and alcohol. I estimate I can remove about 25% of the contamination, by measuring the radioactivity on the tissue, most remains stuck to the glass.

Radon Plate Out occurs because the decay products (218Po, 214Pb and 214Bi) are electrically charged, they are attracted to dust and surfaces that are slightly charged.

Of course it is linked to the cosmic expansion rate, it is the very thing that is making the expansion rate accelerate!

Yes, they're typically genetically identical. Typically a colonial organism begins its life as a single embryo, which is divided up as it develops, budding off new zooids that remain semi-attached (sharing body fluids, nutrients, etc.) but develop independently from that point on.

New zooids being created through budding is a homologous process to asexual reproduction through budding in non-colonial organisms. For example, the zooids in a coral colony are born through budding from an adjacent zooid; corals are related to sea anemones, many of which use the same process to reproduce. The main difference is simply that in sea anemones the new polyp breaks off and leads a completely independent life, whereas in corals the new polyp stays semi-attached and acts as a zooid.

This is somewhat analogous to how cells — both those in your body, and those in single-celled organisms like bacteria — reproduce by splitting apart, but cell division and whole-body budding are two separate processes in an evolutionary perspective.

Colonial organisms can often reproduce sexually, too, but at the whole-colony level, not at the zooid level. In other words, zooids within a colony do not have babies with one another that later join the same colony (there is no such thing as a zooid "joining" a colony, other than by budding); rather, reproductive zooids release sperm and eggs, which meet and become an embryo, and that embryo becomes an entirely new colony, as described above.