Geiger Counter Readings – How Bad is Bad?

The following information may help you understand Geiger Counter Readings, the units of measurement for Geiger Counters (nuclear radiation detectors).

Radiation Units of Measurement

1 rad = 0.01 gray (Gy)
1 gray (Gy) = 100 rad

1 rem = 0.01 sievert (Sv)
1 sievert (Sv) = 100 rem

Rad and Gray are ‘absorbed dose’ units.
Rem and Sievert are ‘equivalent dose’ units.

Rem and Sievert

The units of ‘rem’ and ‘sievert’ relate to biological damage done to human tissue.

These units factor the differences between types of radiation. A multiplication factor (radiation factor) is used that represents the ‘effective’ biological damage of a given type of radiation. This is the main reason for these units – to factor the differences in damage that is caused from one type of radiation to the next.

Radiation Factor (QF Quality Factor)
(1) Beta
(1) Gamma
(1) X-ray
(10) Nuetron
(20) Alpha

For example, the list above shows that a ‘rad’ or ‘gray’ unit of ‘Alpha’ energy that is absorbed by soft human tissue does 20 times more damage than a ‘rad’ or ‘gray’ of Gamma, X-ray or Beta radiation.

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Radiation Dosage

Radiation dosage is a measure of risk – the biological harm that tissues receive in the body.

The unit of absorbed radiation dose is the sievert (Sv). Since one sievert is a large quantity, radiation doses are normally expressed in smaller units, milliSievert (mSv) or microSievert (µSv) which are one-thousandth or one-millionth of a sievert.

For example, one chest X-ray will result in about 0.2 milliSievert (mSv) of radiation dose.

On average, our annual radiation exposure from all natural sources is about 300 milliRem, which is equivalent to 3 milliSieverts (3 mSv). Adding man-made sources (medical procedures, and others) the average annual U.S. radiation dose is about 600 milliRem, which is equivalent to 6 milliSieverts (6 mSv).

Average annual human exposure to radiation (U.S.)
600 milliRem (mRem)
6 milliSievert (mSv)

Radiation dose for increase cancer risk of 1 in a 1,000
1,250 milliRem (mRem)
12.5 milliSievert (mSv)

Earliest onset of radiation sickness
75,000 milliRem (mRem)
750 milliSievert (mSv)

Onset of radiation poisoning
300,000 milliRem (mRem)
3,000 milliSievert (mSv)

Expected 50% death from radiation
400,000 milliRem (mRem)
4,000 milliSievert (mSv)

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NOTE: I will soon be updating the following sections regarding CPM, because it is a unit dependent upon the type of Geiger tube that’s in any given radiation detector. I intend to include (convert to) uSv/hr as well as accumulated dose (uSv) in order to present a normalized set of numbers.

Measuring Radiation with a Geiger Counter (CPM)

Geiger Counter Readings: What are CPM units?

CPM abbreviates Counts Per Minute and is a measure of radioactivity – a unit of measurement seen on some Geiger counters. Technically, “It is the number of atoms in a given quantity of radioactive material that are detected to have decayed in one minute.”

Most Geiger counters are calibrated to Cs137 (Cesium), a radioactive isotope.

1,200 CPM on the meter (for Cs137) is about 1 mR/hr (milliRad per hour).
120 CPM on the meter (for Cs137) is about 1 uSv/hr (microSievert per hour).

How Much CPM is Dangerous?

When does the CPM count become bad?

That depends on how long you are exposed at any given level. It is a function over time. The level itself, and how long.

The Radiation Network website, for example, uses a threshold warning level of 100 CPM for 3 consecutive minutes before sending out an alert. They say “it would be unusual for those levels to exceed 100 CPM”.

So, how do we correlate CPM numbers with dangerous?

First, we must understand a few radiation facts and numbers regarding dosage. By plodding through the math, we can determine a relationship of Geiger counter numbers versus the risks to your health.

For example, the CPM readings that you might see on the Radiation Network Map or elsewhere.

With the radiation dose examples listed above, we can correlate how long it would take to experience those effects based on hypothetical Geiger counter readings given in CPM.

So, let’s use the number 100, since this is the threshold that the Radiation Network website has chosen. The Cs137 calibration factor listed above (120 CPM) was converted to obtain the proper factored results listed below (0.83x). Higher CPM readings are also listed for relevancy.

Days compared with the average annual human exposure (U.S.)
207 (at 100 CPM)
42 (at 500 CPM)
14 (at 1,500 CPM)
2 (at 10,000 CPM)

Days to receive chronic dose for increase cancer risk of 1 in a 1,000
432 (at 100 CPM)
86 (at 500 CPM)
28 (at 1,500 CPM)
4 (at 10,000 CPM)

Days for earliest onset of radiation sickness
25,937 (at 100 CPM)
5,187 (at 500 CPM)
1,729 (at 1,500 CPM)
259 (at 10,000 CPM)

Caution regarding CPM readings:

CPM readings are not necessarily consistent from one device to another.

The Geiger-Mueller tube within the Geiger counter come in all shapes and sizes. Some are incredibly sensitive. Others are not. Some are high quality. Others are not.

The tube on a quality Geiger counter will typically be several times larger than the tube on a cheaper Geiger counter (for example). So comparatively it will always pick up a larger CPM value.

It’s possible for one device to have a reading of 150 CPM while another device only reads 50 CPM. Therefore in a given area it’s best to know the normal background radiation level from your specific device.

 Conclusion: The Geiger Counter readings that one may experience can be compared to the equivalent ‘what-IF’ scenarios listed above for potential health impact. The lower the better. There are lots of theories and opinions regarding long-term effects, dosage vs. health, acute vs. chronic, and the effects of various types of radioactive ionized particles making it into the food chain, etc… Do your due-diligence

Interesting fact:
All food sources combined, expose a person to around 40 millirems per year on average.
Many foods are naturally radioactive, and bananas are particularly so, due to the radioactive potassium-40 they contain. The equivalent dose for 365 bananas (one per day for a year) is 3.6 millirems (36 μSv).

Other foods that have above-average levels are potatoes, kidney beans, nuts (especially brazil nuts), and sunflower seeds.

Ways to limit radiation exposure:

1. Time (limit exposure time)
2. Distance (intensity decreases sharply according to the inverse-square-law)
3. Shielding
(alpha: nearly anything… a sheet of paper will stop it – danger of breathing it)
(beta: wood, water, plastic-acrylic, aluminum)
(gamma: water, concrete, lead)

Disclaimer: The information in this article is one person’s estimation based on several hours research and working through some math.

[ Read: Best Geiger Counter For Preparedness ]

[ Read: Best Gas Mask For Nuclear Fallout ]


  1. So, we have radiation level readings, but is there any way to get readings on WHAT is coming over here? Do we know if its Iodine or Cesium or Plutonium? Seems like that’s more important than the levels themselves…

    1. @Gelaine, Although apparently currently very low readings, we might expect to see Iodine-131, Cesium-137, and possibly Plutonium-239, based on the fuel that had been used in Fukushima. Again, emphasis currently on the very low traces, which are evidently representative of the fact that what we are seeing now is the very beginnings of what happened at Fukushima during Day 1. We’ll see if and how much the levels rise next week to reflect what has happened there during this week. I think we’re OK for now.

      1. Do you still “think we’re ok”? Almost all States have had sustained CPM’s of just the CS-137 of 50 or above. I presume that any raised CPM is bad & that averaging doesn’t matter, since this stuff is coming to rest upon the ground, buildings & cars. Isn’t my presumption correct, because none of these “items” fully deplete in less than a month & no-one’s decontaminating or even testing their water, food, shoes, pets, playing fields, streets, sidewalks, stores, offices, houses or cars. I conclude that everyone has already blown through their typical 600mrem & even their harmful 1200mrem by now. What are your reactions to the reported increase in birth mortalities & alarming findings in food, water & milk…at this late date & after my above possibly flawed reasoning.

        1. Dont worry, the govt raised the safe allowance level, so we’re all good lol

      2. I am working with a Fukushima decontamination project and I am desperately need a Geiger counter that can measure Cs 134 and Cs 137 level of radioactive (bacquerel/kg). Do you know of any such device?

        1. You work at a decontamination project and you aren’t issued one?

        2. Check ebay. Got a smatlabs geiger counter for my android for 25$

    2. Radiation is radiation. Some isotopes will remain radioactive for a longer time though.

  2. The EPA’s website shows the GAMMA GROSS COUNT RATE (CPM) in Anaheim to be in the 3000 range. Why is this so much higher than the alert level you discuss which is 100 CPM?

    1. @Jack, you need to look at this one: “Beta Gross Count Rate (CPM): 17”, which is near the top of the list for each station. All of the others, range 2 through 10, mean other things having to do with the isotopes themselves. The ‘range’ numbers are to be interpreted differently.

    2. If you look at the notes, it says:

      The Gamma Gross Count Rate shows how many gamma rays the monitor detects each HOUR.

    3. The discussions of rising radiation readings, their affect on the human body, and how to interpret the readings is important. But the readings on my kitchen table are 12,000 CPM steady. With fluctuations to 14,000 CPM and more. A small ditch (10 inches deep) next to my house – 22,000 CPM. Apparently the radiation concentrates in the ditch. I believe that we need to talk about our daily survival. We are all contaminated! Let’s accept that and try to keep mankind around for a few more years. I live 10 (ten) miles from the Pacific in central California. My dogs have died. The birds are gone. Bugs are gone. The ocean has limited life remaining. I hope that we are not so egotistical we think that we are not next. Stop by my house any time if you do not believe the readings. The experts have told me that “things are fine, just fine.”, Why don’t I believe them? Stay Safe!
      Stam Peden
      Aromas, CA

      1. bad enuf you need to make sure you have your iodine in and keep iron levels up for starters.. as you pack to leave…which will put it off for a whileif you can get out of the direct wind currents.
        they can’t tell anyone things are not fine, would not be able to keep the roads open. “Acceptable levels”have been raised everywhere.

      2. Have you tested some of the fruit’s and vegetables coming out of the valley ? I would guess all that is contaminated as well !

        Time Lapse Of All Nuclear Explosions Since 1945

        After viewing this it’s not hard to believe that we engineered our own ELE !

        Not only counting Chernobyl and Fukushima all NPP leak from what that say.

        The PTB are psychopaths for doing this to us. They opened Pandors’a box and unleashed this on us !

        So sad.

      3. Anyone want to comment now on radiation levels after the “Pandemic”?
        I have a Berthold LB122 last calibrated in 2016 sat in a wall since. It is picking up 16-20 CPS – 960 to 1200 CPM. Pretty sure the pandemic was and is Nuclear War. PCR is identucal to liquid cintilation for tritium. Thoughts?

        1. Way hard to find truth on the subject of cpm now a days may 2022 ,,,,,,’!

  3. Thank-you for this article. Could you give a reference for the increase in cancer rates related to radiation?

    1. @Luanne, There are a multitude of sources available by doing a Google search. Lots of various opinions about thresholds, etc…

  4. I’m interested in further understanding the level of MOX plutonium headed here and how to logically respond to it.

  5. How does the radiation fallout or the worst-case scenario at the Fukushima nuclear plant compare with the fallout that resulted from US nuclear-bomb tests in the Marshall Islands?

    Does anyone have an idea?

    1. And that’s if it’s just uranium if the Mox fuel – plutonium gets involved and it’s about 2 million times worse I’ve heard

    2. The MA cement dome on top of sand is only starting to wash into the oceans, and results of this irresponsible contamination and irradiation of locals, ecology, and entire world is yet to be witnessed by the entire world.
      The levels of toxicity in marine life has already exceeded threshold of the allowable limits. The rising level of ocean is about to fully wash off the MA island, and residents will forever have no place to call home. The rest of the world will experience what these folk been copping With for decades.
      Why isn’t there a clean up initiated? Something like scoop and lift and underpin then re-cement hopefully from safe distance.

  6. I was considering to start collecting antique vaseline (uranium) glass. However, after reading this page,I am having second thoughts about this hobby!

    Although most vaseline glass sites maintain that it is perfectly safe (unless ground and ingested), I have my doubts. A drinking glass generating 24000 CPM does not sound very healthy to me!

    1. It’s about exposure over time. It is also about distance – distance is your friend. Don’t sleep with your uranium glass next to you in bed and don’t carry it 24/7 with you and you have nothing to worry about.

  7. I really appreciate the efforts by Modern Survival Blog to carefully risks.

    Keep in mind please that these risk levels explained above reflect external exposure to radiation and do not address what happens when radionuclides lodge inside the body after being inhaled or ingested.

    As Helen Caldicott tells us, one atom of plutonium could kill over time if lodged in the body near vulnerable tissues.

    Also, the body mistakes radioactive iodine for the stable form and essentially sucks it up in the thyroid.

    Strontium is confused with calcium and is embedded in bones.

    Furthermore, Chris Busby and others have documented very thoroughly that the risk model explained so carefully above is flawed (no discredit to the very helpful efforts above)and lacks predictive value.

  8. I have done extensive research on this subject and I would have to say that I don’t think alpha particles are the most damaging. I thought that alpha particles were the LEAST dangerous kind and that neutrons were able to pass through a metre of concrete and cause extensive damage to human tissue

    If this isn’t true. Why?

    1. Distance of travel is not key when talking ingested particles. An alpha emitter may not give off a super energetic particle but it’s frequency of emission is (most often?) much higher than a beta or gamma emitter. All it has to do is score tracks through tissue enough times to cause a cancer. Higher freq gets there faster

    2. This is comparable to a person being inside of a vehicle on a rainy day. Imagine the rain is coming down in small tiny drops. Now if you are sitting in your car you are protected from it with a barrier. That barrier can be anything from a piece of paper to your skin to a piece of plastic held over your head. Dry… No problem!
      But, imagine you were outside of your car. Soaked to the bone! No matter how light the mist.
      That is what happens when a radiation source gets inside your body but imagine every single drop of water is sent to the same 1 cm of tissue. That is what causes cancer 20 yrs down the road.

      “One day we caught this rabbit that had been running around outside the plant. We got out there and caught him. Well, we had no idea what we were about to discover! That rabbit was what we called back then ‘Screamin Ass Hot!’ We turned on our instruments which the highest measurement on the Geiger counter was 100,000 CPM. It pegged out! We never did find out how high the reading was! It just buried the needle!”
      Please Note:
      A CPM reading of at least 100 is considered a warning level by the Radiation Network, although the length of time you’re exposed to the radiation is an important factor. Hanford is a nuclear time bomb waiting to explode.

  9. Can anyone answer a question for me. I have a CD-700 and I get 50 clicks per minute, when it clicks it will move the needle half way up the meter scale set on times one. I do believe this is a gamma click. How can I find the gamma ray particle. and how dangerous is this…

  10. Oh yes I forgot to mention this is in a building outside of the building I get zero counts per minute. Could this be a particle from Fukushima in the duct work ?

  11. Question. So my friend bought a geiger counter. We have been dehydrating food samples and testing them for radiation. Fish from Japan, Hawaii, Washington state, Santa Barbara, Alaska, the Atlantic and North Carolina. We’ve also tested local produce. Kale and tomatoes grown in various areas in southern and Central California.
    I understand that the scale and cpm readings you have laid out here are for air born, but do they also work for food. Our tests are showing 30 to 50% above back round. Back round averaging about 36 cpm. So as we stand right now we are not sure what these results mean. Is this a safe level? Can we use the same scale you are using to determine what our results are telling us? Thanks.

    1. I am wondering if rene ever got a the answer to her question. I am interested in testing the food in my area and would like to know how to determine what an unsafe level is in terms of CPM (Counts Per Minute). Does anyone know? Also, does anyone have recommendations of geiger counters to test food?

      Here is rene’s original post from above:

      rene says: September 23, 2013 at 10:39 AM
      Question. So my friend bought a geiger counter. We have been dehydrating food samples and testing them for radiation. Fish from Japan, Hawaii, Washington state, Santa Barbara, Alaska, the Atlantic and North Carolina. We’ve also tested local produce. Kale and tomatoes grown in various areas in southern and Central California.

      I understand that the scale and cpm readings you have laid out here are for air born, but do they also work for food. Our tests are showing 30 to 50% above background. Background averaging about 36 cpm. So as we stand right now we are not sure what these results mean. Is this a safe level? Can we use the same scale you are using to determine what our results are telling us? Thanks.

  12. Attn Tom: Hey, I’m former C-130 flight-crew, and I can say this is within normal range, especially at higher altitudes. The higher we go, the less our atmosphere protects us (as if we didn’t have enough to worry about). It can also be affected greatly (spikes) by sun-spot activity.

    If you ever fly older 747’s, watch out for the DU weight’n’balance in the tail, OK? Also note kerosene fires and older 747’s aren’t a good idea if the DU is atomized.


  13. i have an idea which might work/ it involves concrete sea walls containing mica. mica is opaque to radiation. this is a brief outline. if you want more info- contact me- its free free free.

  14. Rob, nuclear phenomena are complex, as are many topics in science- there are semantics and the different quantifing words mean different things as far as energy, absorbed dose, etc. It’s not done on purpose. You can check out a radiation safety textbook, read a few hundred pages and everything is explained in detail.

  15. There seems to be a massive steam release at Fukushima near the very end of 2013, and now the netc site has most readings in the US in the triple digits, even in the midst of winter storm Hercules on the east coast. There’s been many high readings on Jan. 4, 2014, over 350 CPM, 500 CPM, even a couple over 900 CPM! A very small number of detectors show anything like normal readings in the lower 2 digits, and they are either in a fallout shelter or something else about them doesn’t measure the 600-800 KeV range.

    1. Where on the East Coast is safest? Is the Northern part like Vermont, Maine and new Hampshire or Southern? My family and I want to know where the safest place to live would be. We are willing to relocate to create a safe place to grow food and live sustainable. Does this post mean that the radiation has reached the East Coast?

      Thank you!

    2. I understand the condition is bad!! We are doing a lot of research! We are looking at places on the East coast such as Vermont, Upstate NY, Maine and New Hampshire. If you could go anywhere on the East Coast for safety where would you go and where do you reside now?

      Thanks :)

    3. I just realized that you are talking about readings that were taken on Jan 4th but Jan 4th is not here yet? What did you mean by this?

      1. Typo, I was thinking it was the Jan. 4th when it was Jan. 3rd. Sorry.

        1. I live just east of Buffalo & Rochester, NY, and readings are elevated above 150 at those 2 locations.

  16. I just bought an inspector Exp and am going around the house checking things out. Most background I have here in Medford Oregon is about 35 – 40 cpm. Except for my wifes favorite pottery dish that reads 120 cpm. What is the normal background and what do I do with my wifes dish without being thrown out of the house?

    1. Steve,
      I (at this point) don’t know what “high” levels are, but if the wife’s pottery is high, chuck it. get wife to chuck it. Speaking as a wife, I have always totally understood that high levels are NOT a good/safe thing. I cannot imagine anything which I would not chuck, given this.

      when we bought our last house, it had some lovely stonework on fireplace. we were warned that this stone often came fr pits with high levels. we had someone come and test it, it was ok. but, we absolutely agreed that if levels were high, we would not purchase.

      pottery is not worth the risk associated with high levels.

      1. Thank you for your advice. Crazy thing about it is that we have had it for about 25 years. It has held candy and cookies and now holds the bills. At least I can now send the bills back with a little zip to it.
        Being that I am new to all of this, I took an hour background test and came up with 38.166. I am now sitting here writing this note and see it spiked up to 65. Is this normal or should I wear aluminum foil underwear? I just don’t know what is normal.
        Thanks for your advice in advance.

        1. Steve,
          truly, I am not knowledgeable on specific levels. at the time of house purchase we did a fair bit of research, and honestly snuck the “tester” into the previous owners garage (he had labelling on his vehicle, so we did not want the neighbours etc to become alarmed).

          I suspect there are many readers of this blog who have knowledge or can suggest sites. Also, I recall there is considerable on line. we had found an expert locally, and at the time it was not unduly expensive (considering the cost of a house/ one’s health) to pay.

          also, I seem to recall, the expert mentioned houses/yards often do have high sources of these levels.

          you might find, the wife’s pottery is not your only home / yard exposure source.

          even if you do not hire them, maybe you can do what I have with some other situations.

          hunt around for some local or state experts who do this sort of testing.
          have a few question in mind, and ask each of them, sort of give them to understand you might hire them, but for now just getting info.

          use this info (if you are not hiring) to assess your own measurements, concerns, etc.

          you might find their cost to hire is worth the additional peace of mind/ worth the bigger impetus to convince wife to ditch her pottery. might not.

        2. Steve,
          I have been thinking about what you said,
          a) wear lead underwear, don’t think aluminum will cut it.
          b) I seem to recall, that the expert we hired, stated that specific in home levels will / can vary, depending on air flow.

          for example, he suggested that if there was sufficient air flow “out” of the home/local, it would “carry off” some. (please realize, I am seriously paraphrasing, due to lack of specifics of memory…grin).

          for example, the expert suggested we drive by the home several times day of when he was coming to test, to check and make sure the sellers were not leaving all windows open, maybe even with fans, to increase air flow and “reduce” any levels. he said he suggested this, just in case they were aware of any such problems and wanted to reduce readings, if they suspected we were having readings done.

          so, having tried to explain all that,
          when your levels fluctuated, were there increases in air flow – fans/air conditioning/windows – doors open? etc…

        3. Thank you for the info about air flow. I will do my background test again.

  17. I know I am posting a lot of posts, but I just measured my air filter and with a normal background of 38cpm I read 340cpm. Anyone experience this? My wifes freaking out.

    1. I’ve seen several YouTube videos where air filters were measured and the readings were very high. Keep changing that filter everyday?

    2. You probably have radon, that would mean your airfilter is doing its job at filtering it out.

  18. I remember as a kid on the beach of Santa Cruz CA the surf was red. This is called a “red tide” Harmful algal blooms, or HABs. I marveled at it for a moment and then ran in, swam around without knowing it was harmful. Nobody knew and no government to tell the people it is harmful. With this said, I am also wondering about the health of our sea (pacific ocean) and the impact of the radiation. Not only from Fukushima, but also from the many, many and I mean many radiation dumps we and other countries have done. Not to mention using our ocean as a dump ground for toilet waist and other very nasty chemicals. As a kid, I went to church, and still do. I cannot help but reflect on this verse in the Bible.
    Revelation 16:3
    “The second angel poured out his bowl into the sea, and it became blood like that of a dead man; and every living thing in the sea died.”
    So what do we do? How can we change it? Stop using the toilet? I say that there is not much we can do except voice our opinion that is somewhat like a grain of sand. But with enough voices, you can have a beach.
    – I am now stepping off my soap box. :-)

  19. Yup. What about the hundreds, if not thousands of nuclear weapons tests in the Pacific, in the atmosphere, underground, Nevada desert and wherever the Soviets and others tested? Where did all that radiation go?

  20. At 4:30 PM on 3/20/14 the RADNETWORK website had no readings over 55 on their U.S. Continental map. Comparatively, on the NETC website their numbers range from 13 CPM at Lemaire, LA to 569 CPM at Billings, MT. with most sites across the U.S. at elevated readings averaging between 150 – 200 CPM. What gives with the big differences between the RADNETWORK website and the NETC website???

    1. (CPM of Gamma in energy range 600-800keV) are the readings of most counters on the netc site in triple digits. I don’t know what detector they are using to get that reading, and there’s little way to know exactly what kind of radiation it is. Is it radon or something far worse? Well, these readings do not seem to be coming down with a drought, so it can’t all be rainfall radon anymore (which is typically over 1200 CPM).

  21. Radiation @ Fukushima Dai-ichi MP-1, Fukushima, JP is 2400 nSv/hr; Radiation in downtown Los Angeles is 301 CPM, or 2500 nSv/hr.

    All of America is downwind from Fukushima, and since October 2013, we’ve got the radiation count to prove it.

    Days for earliest onset of radiation sickness 3 x 5,187 = 15,561 /365 = 42.6 years at 300 CPM

    Days to receive chronic dose for increase cancer risk of 1 in a 1,000 = 86 x 3 = 258 days at 300 CPM

  22. I witnessed H bomb test “Bravo” in March 1954 aboard the USS Gypsy ARSD-1. Our salvage ship spent 30 continues days in Bikini lagoon salvaging material off the bottom plus hosing down other equipment. 24/7 drinking water, swimming to set buoys, eating food cooked with water, handling items salvaged and more. Every thing was secret and couldn’t be talked about under threat of court marshal and jail. Never informed of possible health risks. Were not allowed back in Pearl Harbor until most personal gear and absorbent gear were removed from ship. According to now released info,(50 yrs. later) the Gypsy and crew were exposed to 1000 to 2200 mrem/mr per day while in lagoon. Who knows after that. At this time (79 yrs. old) I find I have 3 types of cancer. Feel blessed to have lived this long (lot’s didn’t) brother died at 51 from stomach cancer, but would like to have someone explain in dummy’s language what 1000 to 2200 mrems mean to a human body.

  23. Any experts would teach me whether the reading of 0.12 uSv/h is safe? (detected by GQ GMC-300, Geiger Muller Counter, for 60 seconds, on sea food.) Many thanks in advance.

    1. That is well below normal background levels. You are probably shielding some of the regular background radiation with the seafood. It has a high content of water.

  24. Where I work (Mineralized Core storage Facility) I am exposed to may levels of radiation (from pitchblend) – is there an easy way to come up with a exposure dose?

    The one hour total timer sitting next to my desk reads 9.

    Next to the door into the storage facilty – 25 feet from my desk – it reads 33.05 X1000.

    Next to the radioactive core – it reads 3530 X1000.

    So basically – its from one extreme to the next. I have never been given any training on evaluating or interpreting this radiation monitor. so just hoping someone out there might have some insight.

    Thank you everyone.

    ps – the monitor is “Inspector Alert – Nuclear Radiation Monitor”

    1. You didn’t post what measurement scale CPM, mR/h or uSv/h.

      Lets take the 33.05 reading…

      CPM = 33,050
      mR/r = 33,050
      uSv/h = 33,050

      From the manual….

      Whenever X1000 is shown above the numeric display, multiply the displayed reading by 1000 to determine the radiation level.

      LOL. GLTU.

  25. i live on maui and have for 35 years.
    a week or two ago, an employee of the non profit whale sanctuary organization in kihei, maui
    stopped at all the surf schools in kihei and told the instructors that they should all wash with soap and water when leaving the ocean everytime. They said that they regularly monitor pollution levels, radiation, etc. in the ocean water and that for the last week there radiation reading has tripled from the normal reading they get.
    i have a geiger counter but am lost on how to read what is harmful or not.
    should we be worried out here in the hawaiian islands?

    1. In short, no. NNormal background levels are very low; 3x very low levels are still very low levels.

      that doesn’t mean that you shouldn’t still wash off well after getting out of the ocean. There may be other reasons such as pollution or algae swells or something like that.

  26. Recently we removed a trailer load of materials from work. It measured 12660 cpm. We work around this stuff every day. This level seems high after reading all the previous blogs. Should I be concerned for my future health?

  27. I collect Uraninite and I have one large chunk that puts out 80,000 CPM in Beta and Gamma alone, not counting alpha using a hot dog probe geiger counter. What I’d like to know is just how hot 80,000 CPM is??

  28. I have a vintage 1958 wristwatch and the lume radiates at a high level compared to others I own. My Geiger has a max reading of 9.99µSv/hour, which is what the vintage watch shows close-up. So I made several readings at various short distances from the watch dial expecting the inverse square rule to apply. Thus at 3cms the reading was 8.8µSv/hour, at 4cms: 5.0µSv/hour, at 8cms: 1.24µSv/hour, at 12cms: 0.56µSv/hour. What danger am I in if I wear the watch regularly? The source of the radiation is the radium 226 in the lume that was outlawed in 1960’s in the manufacture of wristwatches.

  29. Hi. I have an arduino based Geiger kit running an SBT11A GM tube. Background correlates to expected in South West UK here of around 0.05 to 0.09 uSv/hr. When placing against my Thyroid area it reads about 200 – 300 CPM and around 1uSv/hr. I can find no net data regarding human body output. Is this a normal reading? I have had no radio therapy. All the available data seems to be related to radiation entering the body but not much about an irradiated body aside from radiotherapy related cases. My only check source is a smoke detector Americium 241 pellet. Any advice most appreciated. Thanks to the admin and all contributors here for running some good data. Really grateful.

  30. had a nuclear stress test with contrast … tested my bodys radiation with Geiger counter first day over 65000 cpm that was the most my Geiger counter would read … took some zeolite count was normal in 2 days … is 65000+ cpm,s normal for a nuclear stress test ?

    1. My wife just had one this morning, and she is reading 500,000 CPM. Ear lobes are the highest (most blood ?)

  31. “The cores of reactors 1, 2, 3. are in the EARTH”
    Stop spreading rumors and speculation, Pattie.
    2017 and no one yet knows whether this has occurred.

  32. Mechanics that were working on a dozer that cleaned off an area which contained radiation dust. The readings came back 539, 575, 668 and 1077 (cpm). The workers that were working on the equipment used compressed air to blow off the equipment. What type of inhalation exposure did they receive? And is that amount dangerous in short and long term exposure?

  33. After having a medical test mri with contrast my cpm went to 29000 for 1 day a few months later after a stress test with contrast my cpm count was over the 65,000 limit on my Geiger counter for 1 1/2 days is this normal …

  34. You people are all fools if you believe any level of man made radiation is safe. There is over whelming proof from Govt testing many years back and recently that the smallest amounts of exposure to man made radiation will always give humans and animals cancer… no natural radiation can ever give you cancer and that is how they fool all of you into thinking it’s the same when it is totally different and toxic to all living animals…
    Do your homework and never believe the so called nuclear experts or scientists that are all lying to save their jobs and get the big pay cheque … traitors everyone of them

  35. its worth pointing out that CPM can be misleading UNLESS you know how the device is calibrated.

    For instance, 2 different geiger counters, with 2 different ( sizes, brands, configurations) of GM tubes in the SAME radiation field will give 2 different CPM.

    You can have one geiger that is super-sensitive and may detect 1000cpm, and a geiger in the same area that is less sensitive will only detect 100cpm. This doesnt mean you are ‘under’ or ‘over’ detecting radiation, it means one geiger is able to ‘see’ it more due to being more sensitive.

    the KEY thing is to look at the trend and know your meter, if your geiger measures 100cpm on monday morning and then the same geiger measures 500cpm in the same location in the afternoon then you have a problem. if you use a DIFFERENT, more sensitive geiger in the afternoon and get 1000cpm that isn’t comparable as you are not comparing like for like.

    Thats why its important to know your NORMAL background levels in your area, for your geiger.

    1. I am new to Geiger Counters. I bought the GQ GMC-300E Plus, a nice little Geiger counter, to test the levels around my cat who would be having I-131 treatment for her hyperthyroid condition. Of course the vet keeps her there a few days until her level is “safe” enough to go home.
      I tested the Geiger counter at home and at work and in all kinds of rooms, granite counter tops, and the CPM was low (0-50 is background). The highest I ever got was 30 or 33 CPM. But usually much lower.
      I drove home from the vet for 2 hour trip with my kitty in her carrier on the seat next to me, and tried the Geiger counter around her at home. It immediately started crackling like fireworks, and alarm beeps went off and it climbed into the hundreds, and very fast up to 2,490 CPM at which point I backed away in a panic. Didn’t know what to do.
      Does anyone know what is going on? The vet assured me their Geiger counter is calibrated at some hospital and her level was safe to go home. It was not a CPM measurement, MR/hr I think.
      Over the days and weeks her CPM numbers went down into the 600s finally and then the 300s and lower. Was I in danger sitting next to her for 2 hours in the car with 2,500 CPM (or higher) of gamma rays?

      1. You were seeing half lives of whatever they used on your cat. I would have actually found that fun and interesting to see in person. A half life is the amount of time it takes for a radioactive element to lose half its energy.

        No you were not in danger, even at 2,490 CPM that’s only about 20mR an hour, so a total of 40 for the trip. Even being near your cat for the few weeks it took most of the energy to decay, you probably still picked up less dose that I did working inside containment at a nuclear facility. I worked very short periods in areas twice that would have been in the 72,000,000 DPM range for just Gamma, plus there was neutron on top of that…that was considered dangerous!

  36. Tested myself 1 hour after stress test using contrast … my Geiger counter was pinned at 65000 cpm my geiger counter limit 1st day, the second day 5000 cpm 3rd day down to 500 cpm 4th day back to normal … are there any long term effects ?

  37. I took my geiger counter on the plane from Cairns to Brisbane and then Brisbane to Auckland and each time the Geiger counter levels rose from 12 cpm at ground level up to 2,500cpm at 30,000 feet. Is this normal or are there radiation clouds in the upper atmosphere from Fukushima? According to the above info that means 14 days of flying puts you in the high cancer risk category.

    1. Go to You tube, put in it’s search bar.. “radiation mitigation,” or ” removing free radicals”…etc. there are herbs you can use…must do full research ..and use with knowledge.. among the things to use are cordycepts…and chorella.. You must know exact procedures…There are several things that can be used..

    2. Cosmic radiation is higher at 30,000′ than at sea level because the atmosphere is thinner and there is less atmosphere above to shield the radiation coming from space. Also different at various latitudes because atmosphere depth changes with latitude. Major problem for aircrew and frequent flyers.

  38. Recently there was an radioactive explosion in Nyonoska, Russia. I saw a clip of a reporter’s Geiger counter with the number 171 on it. Can anyone help me understand what that means?

    1. No, but it may enable you to escape a contaminated area, and therefore continue eating.

      1. Ken
        Do you understand this website?
        I thought that these looked like huge numbers, but then I divided down into literal CPM and got 17.7 CPM for Portland, ME for the year between July 24, 2019 thru July 24, 2020. That seems super low according to this web site’s large numbers. Why would this guy Bob Nichols use such large numbers when 17.1 CPM is really how many clicks there are a minute? I was really shocked at these huge numbers thinking that my aching was because of these high numbers.
        This chart is much clearer on the website.
        Gamma radiation Counts have shot up as much as 21.59% in the last week. The Readings are then annualized and compared with the same city Gamma Readings for 2019.
        RadNet Total Gamma Radiation Data (TGR) NorthEast US Coast
        Week of July 24, 2020
        TGR CPM Annualized City, State Date Read 2019 TGR CPM
        87,824,984 Portland, ME. 7/24 78,648,600 83,059,359 Raleigh, NC. 7/24 72,873,751
        65,368,921 Worcester, MA. 7/24 57,573,062
        42,185,407 New York City, NY. 7/24 33,561,626
        30,001,738 Yaphank, NY. 7/24 25,724,470

  39. I bought a radiation detector several years ago (last decade). It has a timer feature and can count down 10 minutes and give me the total count (beeps) in that time frame. A few days ago, I got a reading of 30 CPM. The highest I’ve seen is just under 40 CPM. I don’t check the radiation often, but there’s a nuclear war threat from Russia this week so I thought I’d tell you how my basement dwelling is doing.

    1. Eric,,
      Curious what gives those readings? Radon? What is acceptable?
      Just curious

      1. Kulafarmer,
        Likely radon. If a Low pressure weather system moves in, he will see an increase, due to more radon seeping out of the ground and maybe the concrete.

        1. Minerjim,,
          The radon is from decaying granite? Learned all that but forgot info

        2. Kulafarmer,
          Radon an element that is formed from decay of radium, part of the decay chain sequence of thorium and uranium on their way to becoming lead.(OK, way to complex of an explanation.sorry) radon is very common in many “basement” rocks, granite included. Also found in many soils on the western slope of the Rockies, in groundwater, Well drill cuttings, etc.
          Thanks for reference to the article Ken! I need to review.

    2. I had a plug-in radon detector for years and it always read 0 or 1, but a couple years ago the alarm kept going off with high readings so I unplugged it. Detectors should be replaced after 10 years and this one was much older, so I figure I need a new detector, and I need to open my windows more.

      I don’t think the readings I got on my 10 minute scan lately were much of radon, but it doesn’t say. Readings are elevated because of Fukushima and might have been around 10 CPM before then. Tonight Russia is attacking a nuclear power plant, so people in airplanes might notice some extreme readings in addiction to Fukushima levels in a few days.

  40. Some important info for those interested in radiation and radiation detection:

    1. CPM (counts per minute) and dose (uSv/hr, mR/hr, etc.) CANNOT be directly compared between different models of Geiger counter – the readings you get depend on the size and shape of the Geiger tube, and whether or not it has a mica window (the only way to detect alpha particles). My most sensitive counter reads 10x higher than my least sensitive one while measuring the same thing.

    2. The world is a naturally radioactive place with cosmic rays coming from above and the uranium-bearing minerals below our feet. You’ll never see 0 radiation unless your detector is broken ;)

    3. Radiation varies greatly depending on your altitude and local geology. Normal background levels get higher as you go up in elevation or if you’re in an area with granite bedrock.

    4. Most Geiger counters are useless for measuring radioactive contamination in food. The tubes in almost all consumer-grade counters (and all tubes without a mica window) just aren’t sensitive enough and would only begin to register far above the levels of contamination that are dangerous.

    5. When measuring background radiation, the only useful data are your average values. Radiation is somewhat random, and sometimes you’ll get an occasional “spike” with no real significance. Just today I averaged 67 cpm with a low of 21 and a high of 97. You need to know your normal average levels before you can say that things have gotten more or less radioactive.

    1. Almost forgot to mention – it’s tricky to tell when radiation levels are “dangerous”. Scientists used to rely on the “Linear No-Threshold Model”, which assumed that any amount of radiation is bad, and that any increase comes with increased danger (for example, twice the radiation being twice as harmful)

      It turns out it’s a bit more complicated. The body is pretty good at repairing damage, and low doses don’t seem to cause much if any harm. That’s not to say that you should go basking by your nearest reactor, but occasional exposure to elevated levels like those mentioned in the above comments isn’t a cause for panic.

      Think of it like sun exposure: Too much can be harmful, but those of us that aren’t vampires can manage just fine. And while the occasional sunburn isn’t exactly healthy, it’s not something that needs to be feared.

    2. Richard C – Great info but you lost me at microsieverts. Can you recommend an affordable model that meets your specifications?

  41. I had found a random article about 4 years ago on the radiation in the sludge from fracking being sold to communities to be used as a de-icer-I have lost all things saved on that past computer–does anyone have any links etc to share on the subject? thanks!

  42. I’ve been working on a construction site for the last 18 months when I recently discovered environmental reports that were withheld revealing the site was measured at background CPM of 7,000 +/- and hotspots of 15,000 to 18,000 CPM in a pre-construction environmental survey.
    When I brought my finding to the attention of the people in charge, they had it tested and confirmed these readings but tell me its safe.
    I’m trying to make sense of this, any input would be appreciated.

    1. Mike, Not my monkey , NOt my circus…. work thru this with more questions.
      you state,..” reports withheld” ..Now,question why would anyone withhold reports of “hotspots”..? “deemed safe”…huumm, for whom? -(? them as long as “they ” don’t work or be there daily?).. meThinks they are covering heavily- from the little i know. Now i ask you… what does that many hot spots damage? what is your health worth.? How do you counter any damage you may recieve? what natural substances can help with that.. mushrooms? serrapeptase?iodine? sea kelp? ..more? what did the Japanese ppl use… ? just askin’

    2. Mike, drag up! Get copies of the test results. Have a good family dr look at health effects that might show up over time because of your exposure and watch for them. Prayers.

  43. I’m looking to purchase a personal meter and need help choosing the right one.

    Background story: In August of 2021 I became very ill with respiratory dis ease which was diagnosed as bacterial phenomena ( tested+ for Covid). Three months later my hair fell out. I am completely healthy now however I am ultra sensitive to radiation. I now attribute my sickness to radiation exposure but can’t prove it.

    Do any of you think that there may be a correlation between covid and radiation exposure? Or illness and atmospheric radiation ( sun storms) exposure? Currently, everyone I know is ill. According to the web site the planetary K-Index peaked at 8 last week. So the K-index correlated with folks getting congested and sore throats.

    Any thoughts ??

    1. It is not impossible for anyone to be a victim of radiation exposure in the United States, and hasn’t been since we…and other…nations started conducting nuclear tests in the 1940s and thereafter.

      It used to be illegal to own a personal, civilian, radiation detector in the U.S., unless you were licensed, or a government employee, whose job required it. We didn’t wish the public to be aware their neighborhood was subjected to fall-out in those days, as it was thought it might negatively effect public opinion.

      If you do not know your area had been contaminated, we were not going to tell you, as the fall-out could not be effectively cleaned up and would diminish in a few weeks. Better to just let ignorance have sway, as any negative health issues, like certain cancers, which took time to develop and the effected people often moved from the contaminated area during that time, preventing easily observed “cells.”

      But, we mapped all of our fall-out from our tests, and we map all the fall-out drifting over the country, created by other Nations, such as China. We might tell some dairy farmers to put their cows in the barn and not feed them any local grass, for a bit, when their locations get some fall-out. But, we don’t tell the people living there to flee, or take any precautions…other than the old one of not eating the snow.

      Interesting how a normal dairy cow can stand much more radiation, and remain healthy, than a normal human can. A happy, radiated cow, who got contaminated by eating fall-out covered grass, could produce lethal, radioactive, milk, which would kill any person, who consumed it.

      If the government is worried about the cows, but not your family, you have something to worry about.

      Interested people can do some research on the fall-out which fell on the Northern United States as the result of an above ground, atomic, test, conducted by the Chinese in the late 1970s.

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