Background radiation levels

[lambert@HAL.HAHNEMANN.EDU]

I have a researcher who needs to know about background radiation 
(ionizing, not UV,...)  levels since the appearance of life on earth.  
Specifically, during the almost 4 billion years of lifes evolution how 
have background levels of ionizing radiation changed?  

I would appreciate RADSAFER's insights and references for this.

Thank you in advance for all of the good information I am about to receive.


Kent Lambert
LAMBERT@hal.hahnemann.edu

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