Radiation Chart Update

Ellen and I made our radiation chart in the early days of the Fukushima disaster. I intended it to provide context for radiation exposure levels reported in the media.  I included a few example doses from monitoring sites around Fukushima (the only ones I could find at the time). But our main goal was to give people a better understanding of what different radiation levels meant.  It wasn’t a guide to what was happening at Fukushima because neither of us had hard data on that.

I’ve recently corrected a few things on the chart (the old version is available here). In particular, I’ve changed the mammogram dose from 3 mSv to 0.4 mSv, based on figures from this paper.  The other figures seem to hold up, and I’ve made only small corrections elsewhere.  I’ve added a few more Fukushima-related doses where I could find data, but they’re examples only—not full coverage of the effects.  Specifically, I added total exposure figures over the weeks following the accident for Tokyo, a typical spot in the Exclusion Zone, and a station place on the northwest edge of the zone that got a particularly heavy dose. Those data came from here (Google cache of now-dead MEXT page) and here.

Unfortunately, the disaster has progressed beyond simple radiation releases—there’s some amount of contaminated water, and radioactive material potentially getting in food. When radioactive material is ingested, the effects get a lot more complicated, and depend on what isotopes are there and how they’re processed by the body. Ellen’s page has a bit more information about that.

For reliable information on what’s happening in Japan, including discussions of the contamination levels, there are two sites Ellen and I recommend. One is the MIT Nuclear Science and Engineering hub, which posts periodic articles explaining aspects of the disaster, and the other is the International Atomic Energy Agency’s Fukushima Accident Update Log, which has detailed measurements from a variety of sources.

Note: Some people questioned the side-by-side comparison of short- and long-term doses.  It’s true that they’re not always the same, and I mentioned this in the intro note on the chart. Combining the two sacrificed precision for simplicity, but I don’t think it was a huge stretch—most regulatory dose limits are specified in terms of a total yearly (or quarterly) dose, which is a combination of all types of exposures.  And for those low doses, the comparison is pretty good; the place duration becomes important is up in the red and orange zones on the chart.

90 thoughts on “Radiation Chart Update

  1. I might not be the first to notice, but there is what seems to be a prefix error on the chart. It’s in the field with the green boxes, third from the top. It says “40mSv” but is graphically represented as 40μSv. No biggie, but might be something to correct. :)

  2. Not sure if you’re still checking it, but in case you are – think I’ve spotted an error. In the red boxes, “Approximate total dose at one station… ” is labelled as 40mSv but has 2 boxes = 20mSv

  3. I found a typo: the “Extra dose to Tokyo” – should probably be 40 µSv, not 40 mSv

  4. I’d like to second Sarah’s request for a poster-scale version. Would buy in a heartbeat. Thanks for all your great work, Randall.

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  7. PLEASE sell both versions of this poster. A normal version and a BANANA version. My credit card is ready. Love your sites!


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  9. I notice that the Tokyo exposure is listed as 40 mSv, and displays as less than the entry above, which is 60 uSv. Then later down the chart, it says 1 mSv = 1000 uSv. I assume the Tokyo exposure is a typo, and should be 40 uSv instead of 40 mSv.

  10. Jul. 9, 2013 – The former head of the Fukushima Daiichi nuclear power plant has died of esophageal cancer. Masao Yoshida died at a Tokyo hospital on Tuesday. He was 58 years old. [...] The utility’s officials say Yoshida was exposed to about 70 millisieverts of radiation from the time of the accident to his resignation. They say it would take at least 5 years for esophageal cancer to develop after exposure to radiation.

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  12. I see a very minor error on the chart. In the quadrant located in the lower RH side of the chart, the first comment is listed as having 40mSv and there should be four (4) small red boxes, not the two (2) shown since each small red box represents 10 mSv.

    Love your site ! ! And I ESPECIALLY loved this Chart ! !

  13. Specifically, I added total exposure figures over the weeks following the accident for Tokyo, a typical spot in the Exclusion Zone, and a station place on the northwest edge of the zone that got a particularly heavy dose. Those data came from here (Google cache of now-dead MEXT page) and here

  14. The following table includes some dosages for comparison purposes, using millisieverts (mSv) (one thousandth of a sievert). The concept of radiation hormesis is relevant to this table – radiation hormesis is a hypothesis stating that the effects of a given acute dose may differ from the effects of an equal fractionated dose. Thus 100 mSv is considered twice in the table below – once as received over a 5-year period, and once as an acute dose, received over a short period of time, with differing predicted effects. The table describes doses and their official limits, rather than effects.thanks

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  16. The radiation is everywhere in nature. It can be non-ionizing radiation (eg, radio waves, light, microwaves) or ionizing radiation (eg X-rays used for medical diagnosis, gamma rays used for therapeutic purposes).

  17. From the point of view of radiation protection, radiation can be divided into two categories: non-ionizing and ionizing, to highlight the threat to human health. Electromagnetic radiation: light, ultraviolet and infrared radiation, radio waves, microwaves, ultrasound belong to the first category.

  18. Hi! I am a high school teacher and would love to have this image printed as a poster for my classroom, as I am teaching a unit on radioactivity when we come back from spring break. Would it be possible for me to obtain the image file? Even if not, thanks for this great teaching tool!

  19. Oops. Sorry, didn’t realize that I can just right-click and hit “save”. Science teacher, but definitely not a computer teacher.

  20. Me parecio super interesante e instructivo, espero que todas las personas que pasen por aca puedan sacarle el maximo provecho a este super servicio de ayuda y a May muchisimas gracias por todo.

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