[NOTICE:  This list may be outdated – See also my DISCLAIMER]

My heart goes out to the people of Japan suffering under the triple blow of the effects of the earthquake and tsunami, as well as the social, economic and health effects of the ongoing Fukushima Nuclear Disaster.

For a quick investigation, I use these:

— — — More details for Japan options, below: — — —

There are several possibilities to check radiation levels in Japan:

  • !–> A map and easy graph overlook can be found at http://new.atmc.jp/ (in Japanese, but available also in dozens of other languages!  click buttons on map for recent data graphs)

A couple direct links (zoom out, un-click checked box, click monitor):

  • Similarly:  This site has been taken down, unfortunately. ;-/ A very large number of monitors across Japan, graphing radiation measurement (in the SI radiation dose unit µSv/h (‘microSievert per hour’ – see Radiation Units for conversion info) also in near-real-time: http://ma-04x.net/all.html   This image (below) is a screenshot I took on Dec 5, 2012 (already Dec 6, 2012 in Japan), showing clearly that radioactive particles continue to be blown around and/or released into the atmosphere:  
http://ma-04x.net/all.html on Dec 5, 2012 at around 3:30 pm PST (Screenshot) CLICK IMAGE or LINK for LATEST: http://ma-04x.net/all.html

http://ma-04x.net/all.html on Dec 5, 2012 at around 3:30 pm PST (Screenshot)

It’s too bad the graphs don’t show the specific locations in English as well, but perhaps the following is helpful: the parent page (http://ma-04x.net/) has this following menu (with my ‘Google Translator‘ translations added):

全国 (福島県は相双地域のみ)  Japan (Fukushima Prefecture is a bi-phase region only)

  • Japanese government’s SPEEDI:  Real-time radiation data collected via the System for Prediction of  Environment Emergency Dose Information (SPEEDI).  See above for new better access.
  • !!–> More for Tokyo:  Aside from the already mentioned, there are (at least) these three live monitors with graphs and important weather information:
  • ! –> Sometimes reports on Ex-SKF News (one-of-a-kind blog, translates Japanese news sources to English)

!!!–> See my tab NUCLEAR NEWS for the more reliable news sources on the topic.

Japanese News Sources

  • NHK World  Live NHK Japan News and Video link (English)
  •  Ex-SKF News (one-of-a-kind blog, translates Japanese news sources to English)
  • Japan Times
  • JIJI Press (English page of the Japanese news service)


The above is for quick reference.   There are more options for news and data to explore below, although some may be outdated.  DISCLAIMER.

Possibly Useful Organizations:

The Institute for Information Design Japan (IIDJ):  “Concerned with the lack of understandable information in the current situation, IIDj is collecting all available measurements to compile a consistent and comprehensive Japan Radiation Map.  Most of the data used are updated hourly …” [Continue Reading]    Screenshot from one of the many data presentation on IIDJ (April 11, 2012):

Japan Radiation Map | 日本語 |
This map shows most recent radiation measurements, collected from different sources. On roll-over specific information is provided for that particular location where radiation levels are visualized by the colored square area’s size. Locations marked with the + sign reveal more locations on zoom-in.
CLICK IMAGE TO SEE LATEST @ SOURCE, http://jciv.iidj.net/map/

[The above saw some changes/edits in 2015]

—- —- —-   —- —- —-   —- —- —-

—- —- —- ARCHIVAL (below) —- —- —-

BELOW:  Most of the links listed below may still work, but where they don’t, I’m leaving it all as-was, as an archive of how this blog got started.   — I put this list together within days after the Fukushima-Daiichi NPP disaster, and improved upon it for many weeks.  It was really good in March-April 2011. Unfortunately some sites have reduced, rather than improved, their access since.  :-/ I’m leaving it as-was for now.  See the newer above link(s), and the Nuclear tab for more.]  /

  • CAUTION: Comparing dose rates is not necessarily a dependable way to gauge dangers from fallout.  See Caution with links at ‘Health Exposure Effects’.

Fukuchima Situation Updates


  • –> MEXT – Monitoring Posts out of 20 Km Zone of Fukushima Dai-ichi.  Data accessible through easy-downloadable PDF-documents with detailed radiation measurements in µSv/hr,  updated every 3 hours. Select a file:  ‘Reading of environmental radioactivity level – (English version)‘ Comprehensive PDF-files with overview of radiation levels in other perfectures, too.

Michael Gakuran – http://twitter.com/#!/gakuranman
Roy Berman – http://twitter.com/#!/Mutantfroginc
Martyn Williams – http://twitter.com/#!/martyn_williams
Tokyo Reporter – http://twitter.com/#!/tokyoreporter

  • –> SPEEDI – System for Prediction of Environmental Emergency Dose Informationis the extensive near-real-time monitoring network of the ‘Japan Nuclear Safety Division’. See clusters of monitoring areas in this image (image is a screen-shot taken March 18, 2011); for Current Measurements, CLICK ON THE IMAGE below, and then select a prefecture to get the most recent data from that prefecture’s many monitoring stations:

Note: These SPEEDI reports are in nGy/hr or ‘nanoGray per hour‘.  See the Radiation Units page for a better understanding of the different units.  The nanoGray allows for differentiation between different absorbtion rates for different species.  Conversion for humans is easy: 1 nGy/hr ≈ 0.001 µSv/hr. On 3/17/2011, a reading of 700 nGy/h thus corresponded with an unusual 0.7 µSv/hr.  See the Radiation Exposure Effects page to help put the measurements into context.

  • –> Independent monitor in Hino City, Tokyo: streaming near-real-time Geiger Counter data, reporting in CPM (in this case: 12 CPM≈ 0.1 µSv/hr), plotted on a nice graph.  For additional questions, see their FAQ page (English below Japanese).   Graph is for reference (with normal levels in the 10 – 25 CPM range (≈ 0.08 – 0.21 µSv)

Click on the Reference Graph below (showing normal radiation measurements, Dec 5, 2010) to access the current measurements:

 –> Hino City, Tokyo

  • TargetMap – Interactive frequently-updated (data from SPEEDI) radiation map for Japan. CLICK ON IMAGE [screen-shot taken March 21, 2011] for most recent measurements reported here:

  • NAZ – Nationale Alarmzentrale (based in Switserland)  Concise overviews of the radiation measurements in Japan.  The map right below [an outdated static screen shot] serves as a reference for measurements on March 19, 2011.  Click on the map(right below) for the most recent measurements reported by NAZ, or check for Updates from the NAZ regarding the situation in Japan. (If you don’t speak German or Japanese, try copy-pasting the text into  Google Translate, or look for a pdf-document like “Radioaktivitätsmesswerte Japan vom 19.03.0900 (pdf)” with the latest date and time.  It may not be best for near-real-time monitoring, it does give a clear overview of the day’s unfolding:

Click on Image for most recent measurement reported by NAZ (based out of Switserland)

  • Additional information can be found on some Twitter feeds. Examples (if any are outdated: search keywords for new/recent):

My heart goes out to the people of Japan suffering under the triple blow of the effects of the earthquake and tsunami, as well as the social, economic and health effects of the ongoing Fukushima Nuclear Disaster.