March 15, 2011


The news from the Fukushima reactor is not good, and it is of particular interest to those of us on the West Coast.  But while it is grim, it is also baffling to the average reader. From the Guardian:

Readings at the plant, taken at 10.20 a.m., varied considerably. Edano told reporters that the highest level around one of the reactors was 400 millisieverts, with a reading of 100 millisieverts around another.

These figures are more than meaningless – they are incomprehensible to most Americans.  What exactly is a millisievert?  Aren’t roentgens the measure of radiation?

No, sieverts are.  They are named in honor of Swedish scientist Rolf Sievert, who studied the effect of radiation on biological systems.

They are part of the SI vocabulary – the International System of measurement (Systeme internationale in French, which is the language in which scientists agreed to the new nomenclature) which was adopted by the scientific community in 196o.

It is a universal scientific system of measurement adopted by almost every country in the world  – except the United States, Burma and Liberia. The truth is, we just can’t handle the metric system, which is the basis of the SI.

Roentgens, btw, were replaced by rems at some point, then in 2006 the SI adopted the sievert. Maybe everyone else got the memo…



  1. what about hawaii? scary stuff…


    Comment by nina c — March 15, 2011 @ 11:18 am | Reply

  2. very interesting but what does that rating mean in life and death impact? thank you Jean


    Comment by avery — March 15, 2011 @ 1:26 pm | Reply

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