The Japanese government (MEXT) has issued a contour map of cumulative radioactive dose in air in the 50 km or so of northeastern Japan around the Fukushima Daiichi site, to 11 September.
Warmth of colour indicates greater radioactive dose. Units: mSv. Source: MEXT.
Also displayed on the map are the 20km mandatory and 30km optional evacuation radius circles.
The map shows that the highest radiation dose falls in a familar plume heading northwest from the station, which is on the coast. The amount of radiation, measured in mSv, is colour-coded so that warmer colours are used for higher amounts of radiation.
The map shows that the highest levels of contamination are in the near vicinity of the station, and that farther areas generally have been exposed to lower doses. However, radiation dose does not simply drop away with increasing distance. The map shows three pockets of higher radioactivity (greater than 50 mSv) within the 20km zone, and one outside it. The standard IAEA maximum safe radiation dose for the general population is 1 mSv/year (the worldwide average background radiation is about 2.5 mSv/year).
The map is based on sampling radiation at many points.
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| Country-by-country report links (in other languages) |
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European Nuclear Safety Regulators Group: all interim reports (whether or not stress tests are completed) Countries with completed stress tests: Belgium France Hungary Spain |
