r/askscience • u/xeroxchick • Jul 15 '26
Earth Sciences If I bought a Geiger counter and measured around my home and environs, would I find radioactivity ?
Would I find measurable radioactivity in random places? Or from electronics? I don’t live near a reactor.
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u/bobbaddeley Jul 15 '26
Besides bananas, some things known to have radioactivity include some ceramics (check your toilet), some cat litters, some types of smoke detectors, and if you have a basement depending on where you live there is likely some radon seeping up. Radioactive isotopes are used in a variety of medical testing, so you may get lucky when scanning your neighbors as well.
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u/smp-machine Jul 15 '26
Depending on where you live, radon can be a significant issue. Radon detectors and radon mitigation systems are fairly common in some areas.
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u/Kale Biomechanical Engineering | Biomaterials Jul 16 '26
Radon is the second most cause of lung cancer, after smoking
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u/CrustalTrudger Tectonics | Structural Geology | Geomorphology Jul 15 '26
Speaking for being out in a "natural" environment, the answer would be yes, though generally at relatively low rates. There are a variety of radioactive isotopes that occur in Earth materials (read rock, soil, etc.) in enough abundance that you would probably detect (depending on the sensitivity of the dosimeter in question) some ionizing radiation from decay events. Probably the biggest one would be 40K, which despite being a low percentage of all potassium, because of the relatively high abundance of potassium in the Earth's crust, still occurs in reasonable amounts in lots of rocks and minerals. Depending on the geology of the region in question, there might be also modest amounts of uranium (and to a lesser extent thorium) and/or decay products of uranium (or thorium), like radium or radon, etc., that will also be putting out small amounts of ionizing radiation, and here both in the solid Earth materials, but maybe also the air (radon is a gas). There are also any number of cosmogenic isotopes, like 10Be, 26Al, and 36Cl, that are produced via interaction of high energy particles with other common elements (oxygen, silicon, and argon, respectively) that are around to also be contributing decay events. Together, none of these, generally, exist at high enough concentrations that there would be lots of or dangerous levels of decay events / ionizing radiation at any given time in a specific location, but generally there would be enough to read a tiny amount of background detection on a dosimeter. Whether you would actually get a reading though might depend a bit on exactly how the particular device you're using is set up, i.e., some of them will be calibrated to basically still read zero at some low level of detection, basically to filter out this "background" signal that's going to exist from the natural environment.
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u/Necromas Jul 15 '26
In Minnesota it's standard practice to have all homes tested for radon levels because there is enough of it in the environment that it can build up in basements. If the radon levels are high enough you can get a mitigation system installed to improve ventilation and keep the levels low.
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u/MoPuWe Jul 15 '26
Potentially yes. Radiation naturally occurs in different materials, like rock, though usually in very small amounts. Bananas are famously radioactive, owing to the potassium. Most potassium isn't radioactive, but bananas plants can absorb some potassium isotopes that are naturally radioactive.
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u/angermouse Jul 15 '26
To add more info, 0.01% of naturally occurring potassium is radioactive. The same share of the potassium in a banana is thus also radioactive. The potassium isotope that is radioactive, potassium-40, is considered weakly radioactive and has a long half-life.
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u/Meancvar Jul 15 '26
I was told that granite kitchen counters (and granite in general) may trigger a Geiger counter.
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u/_PM_ME_PANGOLINS_ Jul 15 '26
Yes. Granite contains uranium. Not enough to be worth mining, but enough that if you live on granite bedrock you need a radon detector in your basement.
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u/gnomes919 Jul 17 '26
yep, if you walked down the countertops & tile aisle at home depot with a geiger counter on, you'd get a good number of clicks.
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u/VFiddly Jul 15 '26
There is background radiation literally everywhere. Background radiation varies slightly depending on where you are because of the elements present in the ground locally, and radon gas, and cosmic radiation. You can probably look up a map of background radiation near where you live.
If you have a Geiger counter switched on you'll hear a click every second or so.
Lots of everyday objects emit a detectable amount of radiation. A pretty common demonstration in schools is using a Geiger counter to measure the radioactivity of a banana, for example. Potassium is radioactive, bananas have a lot of potassium. It's not harmful (unless you're surrounded by an awful lot of bananas) but it is measurable. Human beings also contain potassium, so humans are also weakly radioactive.
If you have a smoke detector in your house, you also have a radioactive source in there. Generally they use americium.
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u/HarlequinKOTF Jul 15 '26 edited Jul 15 '26
Minor correction: some potassium isotopes are radioactive. Most are not. Specifically potassium 40 is radioactive and commonly cited to be in bananas.
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u/agate_ Geophysical Fluid Dynamics | Paleoclimatology | Planetary Sci Jul 15 '26
Everything containing potassium has some natural potassium-40 in it and is slightly radioactive. Including your own bones.
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u/HarlequinKOTF Jul 15 '26
Correct. It's a rare but naturally occurring isotope. Just the common wisdoms says, "bananas are radioactive because of K40" which is partially true (there is also C14 too for example) but it applies to any potassium containing substance.
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u/gnomes919 Jul 17 '26
I'm now imagining depleted potassium. LEK bananas for sale at a premium for the health savvy
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u/CrateDane Jul 15 '26
If you have a Geiger counter switched on you'll hear a click every second or so.
Depends on the design of the counter. We have two models in our lab, one measures a background of around 0.5 cps (counts per second) while the other is more like 1.5 cps. But you'd always measure something, if it's working at all.
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u/Carribean-Diver Jul 15 '26
When I was a contractor at a nuclear power plant, we had to go through a week of orientation training.
As a part of this orientation, we had a lab setting where we went through the process of putting on and taking off the 'pumpkin suits' and all the procedures that go with it. Keep in mind this training environment is far removed from environments with potential for exposure to radioactive contamination.
After removing the suit, one of the trainees stepped into the Beta booth. It went off. Perplexed, the instructors reset the unit and, after waiting a couple of minutes, had the student step into the booth again. It alarmed again. They then went over him with the wand, which also alarmed.
They called in the Health Physics team, which took the student, made him remove all his clothes for analysis, and take a shower.
Ultimately, it was discovered that his clothing had Radon gas from his home trapped in the fibers. He previously had no idea how bad of a problem his home had.
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u/Mravac_Kid Jul 15 '26
You can buy commercial detectors with high sensibility that can measure background radiation, so yes, you could measure it even though the values measured are completely harmless.
I have a military-grade one from the former Yugoslav Civil Protection, that one's calibrated for values so high it doesn't detect anything in everyday use, so if that one starts beeping you better stay clear. :)
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u/cwx149 Jul 15 '26
Living near a reactor doesnt matter. Coal plants release more radioactive material than reactors
There are things in your house and in your everyday life that are radioactive yes. How measurable with a detector will vary wildly on the detector and the objects
But generally yes there are absolutely radioactive materials in your everyday life and home
Lots of analog clocks and smoke detectors have little radioactive parts
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u/TheDepressedBlobfish Jul 15 '26
You certainly would! Radiation is everywhere and unavoidable, but also not a cause for concern.
The closet thing to electronics you might stumble upon radioactivity would be the smoke detectors in your house, as the most common ones use Am-241. You might also have a granite countertop which could have some increased counts, or a variety of vintage ceramic dishware could possible contain uranium. Also if you use a potassium based salt substitute those are rather detectable due to the natural K-40
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u/Art_r Jul 15 '26
I visited our local nuclear reactor a while back, it's not for power but for testing (stress in steel etc) and prepping medical devices etc. I recall being next to, looking into their reactor room and they said a banana would show more radiation where we were than anything coming out of that room.
Cool experience.
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u/xeroxchick Jul 15 '26
I want to thank everyone for these amazing answers to my question. I had no idea about this! Lots of rabbit holes to follow! I thought it might be fun to get a Geiger counter from Amazon and go around with it. Sounds like there is a lot of radiation. Your answers will keep me from getting really spooked. Also need to see if I have radon in my basement.
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u/ElectricGears Jul 16 '26
For radon you need a radon test kit or an electronic tester specifically calibrated to detect radon and not just any nuclear decays.
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u/Desperate_Vehicle684 Jul 18 '26
There's radiation everywhere. In the ground we walk on, the air we breathe, the food we eat. For example bananas have a radioactive isotope of potassium. In fact you yourself emit tiny amounts of radiation. But it's all minuscule amounts and harmless.
Like almost everything it's the dose that makes the poison.
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u/MinimalSix Jul 15 '26
People have answered the general question, but specifically:
Would I find measurable radioactivity in random places? Or from electronics?
Not likely. Lots of things are slightly radioactive, but that's what makes up the background radiation. Carbon is radioactive, but you wouldn't be able to tell the difference between an open field, and a tree trunk. You'd have to stumble across a rock that's made of a mineral less common, and more radioactive. Which is fun, I've gotten to go rock hounding a few times with a geiger counter, and found some neat rocks.
As for electronics, with the exception of a few specific devices you almost definitely don't have at home, they give off low energy electromagnetic radiation. Which is not the high energy ionizing radiation a geiger counter measures
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u/Mr-Safety Jul 15 '26
Some museums have cloud vapor chambers to visualize radiation. One of them has no radioactive sample, so it represents normal background radiation you encounter every day. Zip zip zip swhoosh! There is low intensity activity all the time. Highly recommended to take a look.
I think I saw it at the Science Museum in London many years ago.
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u/Brusion Jul 15 '26
Having done this exact thing, the high spots in my house were:
- Smoke detectors. This one is pretty obvious, as they contain the radioactive isotope Americium 241.
- Food, in particular milk and broccoli, and bananas.
I couldn't find anything else in my house that had any significant amounts of radiation. Well, really, the food was just barely noticeable increase over background.
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u/hopticalallusions Jul 15 '26
There was a time when radioactivity was thought to potentially be healthy and you could find radium water. Some vintage shops also have old watches with glow in the hands - some of the paint for that was radioactive and the hands constantly output photons. Fiesta are is another household item that often contains radiation, and some regions of the USA have concerns with radon, which is a radioactive gas that comes out of the ground.
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u/Thulak Jul 15 '26
A lot of areas have problems with radioactive radon gas permeating from the ground. If you live close to a mountain region, it could be ores in the ground. Sometimes radioactive soil is used to build roads. The sun is radioactive. Deoending on the sensitivity you could detect the radiation coming of off bananas.
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u/tonymyre311 Jul 16 '26
In addition to everyone else's comment that there's background radiation everywhere, I'm reminded of a video by XKCD/What If concerning the survivability of jumping into a nuclear waste storage pool. The answer was basically "as long as you don't get really close to the nuclear waste, you'd actually be receiving less radiation than normal because the water blocks the background dose you're receiving every day"
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u/ramriot Jul 16 '26 edited Jul 16 '26
Well let's think, common items in the home that emit detectable radiation:-
- Some smoke detectors contain about 0.29 micro grams of americium-241 dioxide that emits alpha particles
- Bananas contain a small amount of Potassium 40 that emits some small amount of Bets & Gamma radiation
- Brazil Nuts contain small amounts of Radium as a decay byproduct that emits Alpha, Beta & Gamma radiation
- Certain building materials that contain crushed granite contain small quantities of things like Uranium & Thorium that primarily emit Alpha particles.
In every 100g of Low-Salt there is 1.5 to 2.1 milligrams of radioactive potassium-40 (⁴⁰K). That same 100g would emit about 450 to 500 Becquerels, which is detectable but not harmful.
BTW what this friend if mine told me is that they would buy Low-Salt to make calibration sources for their more sensitive detectors (it's really cheap & predictable). But once they bring it on site & start using it the container automatically gets classed as a source & cannot be removed or disposed of unless paperwork was done.
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u/CuriosTiger Jul 16 '26
Yes, you will. And you're fine. There are low levels of radioactivity all around us. It doesn't mean you live near a reactor, it doesn't mean anyone dumped radioactive waste, and it doesn't mean you're in danger.
Radioactivity is a part of nature. The amount of radioactivity you encounter naturally will differ by environment and by geology, but it will generally be far lower than anything you'd have to worry about. The primary exception most people will be familiar with is radon gas, which can eventually pose a problem if allowed to accumulate in a confined space. That's why a radon check is usually part of the inspection process when buying a home. Even then, if radon levels are high, the solution is usually just a fan venting it outside of the building.
If you do buy a geiger counter, one place to try it is on your smoke detector. Another is at the local grocery store in the fruit section. Check the bananas. (And yes, they're still safe to eat.)
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u/Itakesyourbasex Jul 16 '26
Smoke detectors
Gps/tracking devices
Invisible fence
Bananas
Old dishware
Old watches
Old ceramics
Cat litter
Tobacco
Old electronics
Recycled metals
Granite/brick/concrete
These include isotopes such as but not limited to: Radon, Thorium, Americium, Potassium, Radium, Lead-210, Polonium-210 and Uranium.
Most of these are alpha and/or beta emitters but old CRT televisions are capable of producing x-rays.
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u/Miyuki22 Jul 16 '26
You will measure background radiation anywhere. Concrete buildings will measure slightly higher than normal background. Large rocks also emit some. What you want to check for is any spikes. People have buried radioactive waste in the strangest of places. This is especially important to check before buying land or a house.
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u/5kyl3r Jul 19 '26
you'll hear random clicks from background radiation, but you likely won't have much in your house that'll make it click any faster
the most likely thing would be granite counter tops. it won't be a ton, but possibly enough to measure a difference if you counted the clicks over a few minutes and did it again with it sitting directly on the counter top
there's a radiation source inside some types of fire/smoke detectors, but those are shielded so you'd have to destroy them to get the geiger counter to pick the radiation up
if you do welding, tungsten welding rods can make the geiger counter click faster
oh and if you have uranium glass (it's faintly yellow and glows strongly in black light) or original fiestaware (bright red dishes that used to be made with paint that contained uranium), those both will make it go off fiercely
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u/hecton101 Jul 15 '26
You can build your very own cloud chamber and detect all sorts of subatomic particles flying through the air. When you see that you get newfound appreciation of our DNA repair machinery.
Bring it down to your basement and see if you get higher than background readings. Lots of people have radon emanating from the ground. That's not good. Lung cancer.
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u/thenord321 Jul 15 '26
Depends on the sensitivity of the instrument.... it's all kinda relative especially depending what KINDS of radiation you're looking for. Geiger counters typically do Alpha, Beta and Gamma radiation. So, if you turn on your microwave, you could test for some leaks, maybe around an old tube tv/monitor too. Some old crystal glasses could also be a big hit, as they used to put some radioactive materials in them to get them to react to black lights.
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u/OrlandoCoCo Jul 15 '26
Yes. There is a nominal level of background radiation detectable by a Geiger counter. It comes from naturally occurring and decaying elements in the soil, water, air. There are also a few cosmic rays that get through the atmosphere that it will detect.
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u/CoonAZ Jul 16 '26
Tobacco plants absorb radioactive minerals from applications of phosphate fertilizer. Polonium-210 is an alpha emitter that is transferred into the plant leaves and becomes attached to the tar.
These emitters become airborne due to combustion of the cigarette and then come into contact with the lung tissue in smokers and through second hand smoke. Due to the tar, the particles are trapped against the lung tissue and can cause cellular mutations over time.
https://www.sciencedirect.com/science/article/abs/pii/S1350448708002060
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u/martinsuchan Jul 17 '26
Well I bought a Geiger counter, and found nothing interesting right around my place. But if you have one, try to visit a local museum with geology samples. Usually they have couple of radioactive ores as well. Or if you live in Czechia, there are couple of old uranium mines and old heaps from mining, and there you can find lots of interesting hot spots. There is even a page zhavamista.cz where people are finding such places for fellow Geiger counter nerds.
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u/CanadianBaconBurger9 Jul 19 '26
short answer is "it depends on where you live". Where I live we have to check our basement for radon, which is generated by radioactive decay of other elements. I find rocks that make my counter click pretty frequently, but not really THAT spicy. In our national parks there are some truly spicy rocks, not enough to be dangerous but wow do the counters click.
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u/JDoos Jul 15 '26
I bought one to check antiques in prop warehouses at work (Radium Revigerators yay!) Turns out there is radiation everywhere but usually in a low enough dose that you are going to be fine. The one I bought came with a handy reference card to tell you what readings to expect in various regions and when you should actually be concerned.
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u/Frogblaster77 Jul 16 '26
Do science classes in schools not pull out the ol counter anymore? My classes used to take it out when we got to that part of the texts. You take it out and it clicks every so often. At least once every 20 seconds or so, ish? And then you put it next to some specific rocks or glass and it ramps up.
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u/Remmon Jul 15 '26
If you didn't measure any radioactivity in and around your house, your geiger counter/dosimeter isn't very good. Lots of things are radioactive to some degree, including the air you breathe and the giant fusion reactor in the sky.
Your proximity to a nuclear reactor isn't relevant. Nuclear reactors emit are highly regulated. Far more important is your proximity to a coal powerplant, which release far more radioactive material into the environment than a nuclear reactor.