Gavin Shoebridge – an electric vehicle nut, a keen environmentalist

                Electric Car Conversion Blog By Gavin Shoebridge

January 6th, 2012 at 10:44 am

Really Simple Guide to Radiation Levels in µSv/h and mSv/h

If it starts showing this sort of reading, put on your jogging shoes...

If it starts showing this sort of reading, put on your jogging shoes...

How much radiation is too much? What level is considered safe?

Radiation levels can be a very complicated thing to figure out, with alpha, beta, and gamma rays to understand. I won’t go into details, or you’ll have 10 pages of reading to do, so I’ll just post a chart of what levels of radiation are safe to live in - and when it’s time to start running!

So, here’s a simple, plain-English chart of radiation doses in millisieverts (mSv/h) and microsieverts (µSv/h) per hour. Most dosimeters (the handheld Geiger counters that measure your body’s “Dose”) operate in these units.

Simplified hourly dosage rates

Simplified hourly dosage rates

It’s quite a simplified chart, and it helps to know that radiation gets more dangerous, the more your body gets. If you get a big amount of radiation in an hour, it’s more hazardous than getting the same amount over an entire year. This chart is measured in an hourly dose, just like what your meter will probably show on the screen.

I hope it offers some help to those learning to use their radiation meters, and feel free to add more information in the comments below. There’s a very handy radiation level conversion site here too:

* Please feel free to reuse this chart; just be sure to accredit my website.

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  • Damcho Dronma
    7:46 pm on May 4th, 2012 1

    it’s a good chart for simplying conversions; however it should be noted that The chart is handy for conversion, no doubt. However, there is no ‘safe’ level of radioactive exposure. There is always risk: all exposure a person receives, no matter how small, can lead to cancers or genetic damage or genetic damage to reproductive organs, therefore, to future generations. That’s why man-made radioactive product, through weapons, waste and even medical devices is something that should have ceased long ago. The overuse of medical use of radioactivity should be very strongly considered as it too is hazardous.

    Bulletin of Atomic Scientists

  • Ian
    3:12 am on November 16th, 2012 2

    I’ve been looking for a table like this for ages, thanks. I live a couple of hundred km from fukushima so this is very helpful when considering the kids.


  • amit
    9:44 am on September 18th, 2013 3

    Tnx for sharing such great information in brief. Its really help full for initial study about radiation.

  • Roger
    2:54 pm on October 8th, 2013 4

    Galvin, thank you for the table. Is there a dose rate meter in the price range of $150-$200 that you could recommend?

  • gavin
    11:57 pm on October 8th, 2013 5

    Hi Roger, you’re very welcome. I bought mine from eBay from a Russian seller. Unfortunately the good ones are not cheap. Mine is a Russian built dosimeter which cost something like $300 new if I remember correctly. I just had a look on ebay and found these however, which surprised me at how cheap they are:
    Edit: Ah, those are electromagnetic radiation – something completely different. This looks acceptable, and is in your price range:

  • cheryl
    4:51 pm on January 1st, 2014 6

    I need to what a reading of 67mSv h means?
    I’m very concerned if I should move back to LA from SF and I’m bad at math. Anyone tell me is this a high reading please.
    Thank you

  • Brandon
    1:01 pm on March 17th, 2014 7

    This is a fantastic table for understanding radiation tables! Thank you for this and your nice explanation. I will definitely be showing this to my clients!

  • kazuko hotta
    1:59 pm on September 23rd, 2015 8

    You have very comprehensive practical to understand the invisible ‘cannot feel’ radioactive.

  • Chris
    7:41 pm on November 26th, 2015 9

    My Terra-P reads 0.08 to 0.11 uSv/h under normal conditions, in east-coastal Australia.

    It works. The alarm has only gone off only once, when a farmer was doing soil moisture testing near me (his testing device contained radioactive material I found out, when I hunted down the cause of the alarm)

  • Glenn
    7:11 pm on January 2nd, 2016 10

    Gavin, for “Safe: Short-term habitation only”, about how many minutes of exposure time is considered safe?

  • Tom Griffin
    2:28 am on March 2nd, 2016 11

    Gavin many thanks. Im lying in a hospital bed after recieving radiation treatment. Your table has enabled me to understand the reading and understand risk. As im going home today youve been a great help to my family and friends. Thanks bud.

  • gavin
    2:59 pm on March 2nd, 2016 12

    That’s very kind of you to say, Tom. I wish you a speedy recovery and that you enjoy the good things in life.

  • Patrick
    2:30 pm on April 25th, 2016 13

    Hello! I just purchased a keychain with a small tube inside which houses hydrogen-3. The vial is encapsulated with a — what looks like — epoxy plastic. I was curious if there would be any harm from the Beta particles being given off. Also, is there a chance of being contaminated to radiation from the exterior of the casing during its manufacturing? What are your thoughts on these types of trinkets?
    Any info would be great!

  • gavin
    11:56 pm on April 25th, 2016 14

    Hi Patrick! I had a look around the web and it seems that you have nothing to worry about, just don’t break the capsule and eat it. It’s a “low energy emitter” of beta particles which are too weak to even penetrate human skin, so you’ll be fine.

  • Anonymouss
    7:53 am on May 6th, 2016 15

    I’m surprised how little information can be found on the dangers of radiation. I’ve had radioactive iodine treatment and was discharged after 18 hours because there was only 14 usv/h on 1 metre. I was told it was safe for my surroundings and I could do whatever I want as long as I keep 1 metre most of the time. I’m confused,because your table says that such an amount is dangerous. I’ve been home for 3 days and my housemates have been home too. So they’ve had a lot of radiation coming from me. Should I be worried for them and what can I do now to reduce the risk? How much will they absorb on for instance two meters? Is there a formula for that?

  • William
    3:11 am on April 19th, 2017 16

    Hi, thanks for this page.

    mine is FS2011+. I bought it via aliexpress. Made in China and probably passed quality check.
    It reads 0.08-0.13 uSv/h at home Mandalay, Myanmar. I use it to scan hospital X-ray machines. I tested it once with an industrial grade geiger. The results telly.
    Default alarm setting is
    Dose rate 0.5 uSv/h or above.
    Dose 0.05 mSv.
    How about the setting in your machines?
    Best wishes

  • ton
    11:31 am on July 29th, 2017 17

    Can anyone helps explain why my RADEX geiger counter reading is still high (25.5 usv) after 4th day of receiving radioactive iodine? Shouldn’t this number getting lower?

    I am told by doctor that my isolation period is 3 days minimum after that I should stay about an arm length from family members for 7 more days.

    According to this chart. My reading of 25.5 usv (now not dose) is high danger. I appreciate all the help.


  • ReyT.
    10:07 pm on November 28th, 2017 18

    Thank you very much for sharing this useful table.

    Our average reading that we have is at 0.2 uSv/h, do we still need to isolate the machine and enclose?

    thank you,

  • Nick
    3:18 am on March 10th, 2018 19

    There’s an excellent explanation of relevant risk from Professor Geraldine Thomas of Imperial College London. She was a lead researcher in Fukushima.

    Gerry Thomas (Professor of Molecular Pathology at Imperial College London) emphasizes the prevalence of misconceptions related to radiological risk as well as the range of factors that can influence both dose and exposure to radiation. Gerry Thomas Highlights Misconceptions over Health Impacts of Nuclear Accidents


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