Most excellent question.

To convert from counts per minute (CPM) to milli-Roentgen/hr (mR/hr) you have to make some assumptions.

Assuming a Cesium 137 sensitivity conversion, 1,200 CPM = 1 mR/hr.

So... the immediate danger threshold is between 50 and 100 Rads. That's when you start loosing your cookies and hair.

We saw 165,000 CPM in the video. That's 137 mR/hr or 0.12 Rads per hour. At that rate you would reach the 50 Rad zone in 17 days. You would reach your average yearly exposure in 3 hours.

This Fukushima disaster is serious business, and I wonder if large parts of Japan will be inhabitable from a generational standpoint.

More bad news: Internal exposure to hot particules is estimated to be 300 - 500x more damaging than external exposure.


From Modern Survival Blog:

[link to modernsurvivalblog.com]

"Days compared with the avg. annual human exposure (U.S.)
207 (at 100 CPM)
42 (at 500 CPM)
14 (at 1,500 CPM)
2 (at 10,000 CPM)

Days to receive dose for increase cancer risk of 1 in a 1,000
432 (at 100 CPM)
86 (at 500 CPM)
28 (at 1,500 CPM)
4 (at 10,000 CPM)

Days for earliest onset of radiation sickness
25,937 (at 100 CPM)
5,187 (at 500 CPM)
1,729 (at 1,500 CPM)
259 (at 10,000 CPM)"