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Tuesday, 22 January 2013

[Column] What is Sv, Bq, Cesium, how and why it matters

Fukushima Diary

I’m often asked what is Bq/Kg and what is Sv/h etc.. I’d like to explain it in the most casual way in the world.
For example, if I shout from the window, my neighbors are annoyed. My voice to be heard by my neighbor is Sv. Sv = 1000 mSv = 1,000,000 ╬╝Sv.
and if you put your ear directly on my mouth, that would be louder. This is Bq.
How much you are annoyed is Sv, how noisy I am is Bq.
so even if I’m 10000000000 Bq/Kg, if you are so far from me, you don’t hear me (0 Sv/h). On the other hand, even if I’m just 1 Bq/Kg, if you are 1cm away from me, you’d be so annoyed (100 Sv/h or something).
This is why you cannot use a geiger counter to know how much food is contaminated. It would only show how much radiation the geiger counter caught emit by the food. As it flies, radiation is weaken. To know how much it’s contaminated, you need to take it to a lab and analyse. The result is in Bq/Kg.

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