I think the core of the explanation given is correct but some of the adjacent details need adjustment. The important part is:<p>"Clothes dryers are very effective at making statically charged surfaces. (Dryer sheets help.) So when radon and its temporary decay products are blown through the dryer, electrically-polarized molecules tend to be attracted to the charged surfaces"<p>What that commenter misses is that nearly all hobbyist grade detectors (Geiger tubes) are not sensitive to alpha but they are highly sensitive to beta and a little sensitivity to gamma. However, any thin solid will block beta, so they would need the Geiger tube to be very near the radiation emitting material to pick up the beta. In other words, if they're just waving the detector around they're probably just catching the gamma.<p>The radon in the air decays into various progeny, and by the time it reaches the dryer that will be to some extent in equilibrium, so several isotopes, including gamma emitters, will be present in the mix. Therefore I'm not surprised the detector reads a tiny bit of that.<p>Why it dissipates is probably not a decay thing but rather the accumulated material gradually diffusing away from the filter or whatever after the dryer is turned off and no longer actively accumulating radon.<p>This could be tested by putting a detector right next to the filter to see how much beta it picks up. I've basically done that with a home air filter:<p><a href="https://twitter.com/BetterGeiger/status/1605639346865901570?s=20" rel="nofollow">https://twitter.com/BetterGeiger/status/1605639346865901570?...</a><p>That's with the detector I make and sell which is primarily sensitive to gamma, which is why I could register a reading through the plastic container, even a couple days after preparing the test. When I used a pancake style detector sensitive to alpha and beta, directly against the exposed filter, the detector reacted much more strongly... But the Better Geiger S-1 gives an accurate <i>dose</i> reading, the Geiger tube or pancake probe will dramatically overestimate dose in that scenario, which can cause undue concern... In reality it's pretty harmless levels of radiation. :)
I haven't read much on physics before. My favourite thing to do on these stack overflow sites (or on specific tags) is to go to Questions -> sort by score, and just read through the top questions and answers. It's a bit hidden away because they want to steer people to the active questions, not to established ones.
> I was once prevented from leaving a neutron-science facility at Los Alamos after the seat of my pants set off a radiation alarm on exit. This was odd because the neutron beam had been off for weeks. It was a Saturday, so the radiation safety technician on call didn't arrive for half an hour — at which point I was clean, so the detective questions began. I had spent the day sitting on a plastic step stool. The tech looked at it, said that radon's decay products are concentrated by static electricity, and told me that I needed to get a real chair.<p>Hilarious
Reminds me of the story about how Radon was discovered (well the fact that it can accumulate in homes). The story goes that a worker at a nuclear power plant kept on setting off the detectors when coming in to work and eventually they investigated his house.
We had this issue in the Midwest (central Illinois). Can’t remember exactly why, but radon would accumulate in the basements. Had to have sensors and ventilation for it.
I saw this nice visualization of radon decay time at <a href="https://www.reddit.com/r/dataisbeautiful/comments/13fw2uh/oc_radioactive_decay_of_radon_progeny_in_dryer/" rel="nofollow">https://www.reddit.com/r/dataisbeautiful/comments/13fw2uh/oc...</a>
Florida is about to build some test roads using phosphogypsum, a radioactive waste product of the fertilizer industry that has been piling up and they want to unload.<p>It contains high quantities of radium which decays into radon, this should end well.<p>> "Phosphogypsum contains appreciable quantities of uranium and its decay products, such as radium-226," according to the EPA. And because the fertilizer production process concentrates waste material, "phosphogypsum is more radioactive than the original phosphate rock," the agency notes.<p>> "The radium is of particular concern because it decays to form radon, a cancer-causing, radioactive gas," the EPA adds.<p><a href="https://www.npr.org/2023/05/09/1174789570/florida-roads-radioactive-paving-phosphogypsum" rel="nofollow">https://www.npr.org/2023/05/09/1174789570/florida-roads-radi...</a>
This is similar to a fun trick I used to show people back when CRTs were the predominant television screen. The face of the TV would build up a static charge and collect dust over time. I’d wipe the screen off with a damp paper towel and place it under a alpha/beta/gamma-sensitive Geiger probe. It would hit 500 counts per minute easily(background was about 250).<p>I knew people who took this to an extreme by putting a high-voltage static charge on a needle, then placing the charged needle in a closed bell jar with a pile of thorium-doped lantern mantles. The tip of the needle would pick up enough radon daughters that it made a great rechargeable point source for cloud chamber demonstrations.
I doubt it has anything to do with molecular dipoles. More likely I'd guess ionized radionuclides adsorb onto macroscopic dust particles (or some similar mechanism), which then maintain a net charge imbalance.
Interesting that the second answer mentions the enhanced radioactivity of laundry detergeant. One of our smoke detectors briefly went off the other day as I walked under it with a basket of wet clothes straight out of the washing machine. Any chance that's what it was?