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Radiation Levels In Japan


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1) Those interested in recently (?) measured radiation levels (at different distances from the Fukushima reactors in Japan) should see:



(dose levels measured 1 meter above the ground)



(dose levels measured 1 centimeter above the ground)


Note that the color code is explained near the lower left corner of each dispay. Radiation levels are expressed in micro-Sieverts per hour. [The 10 micro-sieverts, for example, is the same as 0.01 mSv, etc. And 10 micro-Sievert/hour is the same as 0.24 mSv/day, or 7.2 mSv/month.]


2) The effect of penetrating radiation on a person depends on the dose received. The common unit of dose is Sievert (Sv). Smaller doses are expressed in milliseverts (mSv) or microseveret.


A dose of 10 Sv will most likely results in death, within a day or two.

5 Sv would kill about 50% of exposed people.

2 Sv can also be fatal, especially without prompt treatment.


0.25 Sv = 250 mSv is the limit for emergency workers in life-saving operations.

0.10 Sv = 100 mSv dose is clearly linked to later cancer risks.

0.05 Sv = 50 mSv is the yearly limit for radiation workers.


0.004 Sv= 4 mSv typical yearly dose due to natural radiation (cosmic rays, etc).

0.003 Sv= 3 mSV typical dose from mammogram


Ludwik Kowalski (see Wikipedia)


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