Radiation Chart

There’s a lot of discussion of radiation from the Fukushima plants, along with comparisons to Three Mile Island and Chernobyl. Radiation levels are often described as “<X> times the normal level” or “<Y>% over the legal limit,” which can be pretty confusing.

Ellen, a friend of mine who’s a student at Reed and Senior Reactor Operator at the Reed Research Reactor, has been spending the last few days answering questions about radiation dosage virtually nonstop (I’ve actually seen her interrupt them with “brb, reactor”). She suggested a chart might help put different amounts of radiation into perspective, and so with her help, I put one together. She also made one of her own; it has fewer colors, but contains more information about what radiation exposure consists of and how it affects the body.

I’m not an expert in radiation and I’m sure I’ve got a lot of mistakes in here, but there’s so much wild misinformation out there that I figured a broad comparison of different types of dosages might be good anyway. I don’t include too much about the Fukushima reactor because the situation seems to be changing by the hour, but I hope the chart provides some helpful context.

(Click to view full)

Note that there are different types of ionizing radiation; the “sievert” unit quantifies the degree to which each type (gamma rays, alpha particles, etc) affects the body. You can learn more from my sources list. If you’re looking for expert updates on the nuclear situation, try the MIT NSE Hub. Ellen’s page on radiation is here.

Lastly, remember that while there’s a lot of focus on possible worst-case scenarios involving the nuclear plants, the tsunami was an actual disaster that’s already killed thousands. Hundreds of thousands more, including my best friend from college, are in shelters with limited access to basic supplies and almost no ability to contact the outside world. If you’re not sure how to help, Google’s Japan Crisis Resource page is a good place to start.

Edit: For people who asked about Japanese translations or other types of reprinting: you may republish this image anywhere without any sort of restriction; I place it in the public domain. I just suggest that you make sure to include a clear translation of the disclaimer that the author is not an expert, and that anyone potentially affected by Fukushima should always defer to the directives of regional health authorities.

809 replies on “Radiation Chart”

  1. Mr. XKCD, your site and your graph have been featured in the UK’s “The Guardian” and the Austrian “Der Standard”. Congrats! 🙂

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  2. Have I ever mentioned how much I love your (Mr. Munroe) intelligence. If I didn’t have xkcd I’d sufficiently deficient of it! This is just a thanks!

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  3. I think it would be neat to add the exposure that you’d receive standing in front of the US Capitol Building. I found a source that said the yearly exposure was 850 µSv. The Capitol wouldn’t be licensed to operate as a nuclear power plant!

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  4. @stevie
    The article stevie linked to is a bunch of hyperbolic BS…

    Chernobyl exposed 220,000 people to doses over the lowest amount linked to cancer, and killed 28 people outright, and still only caused approximately 4000 cases of cancer.

    Since Fukushima only exposed around 200 people to similar doses, we can really only expect around 4 people to get cancer from the exposure.

    Similarly, while chernobyl released 50% of the reactor mass in soot from the inferno, including the longer lived decay products. Fukushima released only the water soluble iodine 131 and cesium 137, and the iodine only has a half-life of 4 days, so it is already a non-threat to returning residents. (most of the exclusion zone has already been lifted, with the exception of a small area with large amounts of cesium contamination.)

    And quite frankly, it is hard to consider the plant operators who caused the accident “victims of radiation”.

    The fukushima reactors are the same design that was successfully contained at 3 mile island, and if they had just bit the PR bullet and released the contaminated gas buildup like at TMI, then there would have been no hydrogen explosions to contaminate the surrounding area and damage the containment structures.

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  5. A friend of mine said his 9th grade daughter asked him why don’t we use the space suits used to walk on the moon to protect against radiation at Fukushima’s reactor for repair? Can any one answer?

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  6. Re: Jack –
    The space suits did not provide adequate radiation protection. The early astronauts that went to the moon have suffered from many complications due to the increased radiation they were exposed to.

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  7. Space suits are great, but their radiation protection is limited. Moreover, a pace suit is quite heavy (e.g. EMU is 124kg with all eqipment, and at least 50kg without life-support), as they were designed for zero gravity.
    They also do not offer a too good protection, as intense radiation events (e.g. solar flares) could kill an astronaut in a space suite outside, and even during low-radiation periods, astronauts are allowed to spend only relatively short periods of time outside, to limit radiation exposure.
    For detailed info see e.g.: http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.118.2763&rep=rep1&type=pdf

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  8. To all potential Armageddon whiners or fatalists, I have to say, I am extremely [REDACTED] disappointed. Please, keep your proportion blowing comments to yourself, for the good of all parties involved.

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  9. Look at the space between the corners of the squares on the chart. Randall can’t get enough of that illusion, can he?

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  10. Look at the space between the squares on the chart. Randall can’t get enough of that illusion, can he?

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  11. Cell phones might not emit any radiations, and be safe on that side, but that is not the only way to kill someone…
    A cell phone is producing micro waves which effects on brain are far from being fully known atm…

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  12. ../…../ˉn……..(‘(…′…′….ˉ~ /’)
    ……………………..’../
    ………………………./
    ……………………..(
    …….

    Google in the input: = tntn.us ==you can find many brand names, even more surprising is that he will sell you the unexpected o(∩_∩)o

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  13. well done, but I found a mistake.
    it’s said that using a cell phone does not produce ionizing radiations and does not cause cancer. the latter is not true: using a cell phone exposes to radiofrequency electromagnetic fields and is possilby carcinogenic to humans (see WHO/International Agency for Research on Cancer Press Release N° 208).

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  14. URGENT–IMPORTANT TYPO

    There’s a clear typo on this chart that I can’t believe no one has noticed… Fukishima is listed as having received 70msv instead of 70PICOsv. According to what is graphically represented, that is a typo. If it is written correctly, then it is grossly misrepresented graphically. Which of the two is it?

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  15. Maybe it’s just me, but this graph seems a bit misleading in parts. You’re graphical representation is smart and intuitive as far as communicating the relationship between radioactive events in terms of absolute quantities of radiation emitted. But you’re not doing much for the parameter of time, that is rate of exposure, and you said yourself this is integral to the damage done. Yes you occasionally mention “over a year”, but is it apparent that your graph then visually represents ONLY total amount of radiation absorbed, and not the amount of damage dealt?

    You state the lowest one-year dose linked to increased cancer is 100 mSv, and the dose received by 2 Fukushima workers was ~180 mSv. For all I know those workers were killed within seconds because they were hit with that radiation all at once, which is like 1000 times worse than increased chance of cancer, instead of just 1.8 times worse. This sort of ambiguity in danger levels, caused by the omission of rates of absorption/exposure, is bad in a graph meant to clear things up when it comes to radiation poisoning, especially with respect with Fukushima.

    I’m sorry if I misunderstood the graph. Your comic is awesome.

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  16. Larissa what exactly defines prolonged use though? I think for the most part people are not spending more than an hour a day on their phones. My biggest concern would be how close it is to you while its not being used. Keeping it in the same pocket all the time while its on can’t be good and could be much more dangerous than active use. Just my opinion. Great read.

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  17. Well written however I think these days we have more to worry about than cell phone radiation and kitchen appliances emissions. Interesting to read how scientists are measuring radiation conditions. Pura vida!

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  18. I really dont think theres much danger in kitchen appliances emissions… lets not get carried away here. The cell phone theories may be true but contradicting studies are released so often now that its hard to take anything as truth. Be cautious, but don’t worry… that will do more harm then radiation.

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  19. This is total and complete news to me as well! I found this helpful in clearing up some of the misinformation out there, and the dosage comparison has been interesting to see.

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  20. So if sleeping next to someone is 0.05… if I sleep next to 20 people I’ll get sick?

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  22. Still a great chart but are you going to update it, now that they messured 10 Sievert per hour on a drainpipe between Fukushima 1 and 2?

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  23. Shouldn’t Extra dose to Tokyo in weeks following Fukushima accident be 40 microsieverts instead of 40 millisieverts? (If not, I’d be worried…)

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  25. Note that there are different types of ionizing radiation; the “sievert” unit quantifies the degree to which each type (gamma rays, alpha particles, etc) affects the body

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  26. tobacco cigarettes info would be interesting here, it’s not very well known that most cigarettes are radioactive

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