[palmer]

Here's a link regarding potential harm to humans: http://www.merckmanuals.com/professional/sec21/ch317/ch317a.html#sec21-ch317-ch317a-605 It doesn't answer your specific question, but at the peak reading from yesterday (400mSv/hour) there is 20% increased risk of cancer from 2.5 hours of exposure plus up to five percent chance of death from radiation sickness from anything longer than that.

[mn-bush-man]

It’s always hard to interpret numbers. A 20% increased risk of cancer... so if, prior to exposure, I had a 5% risk of cancer, would I have a 6% risk of cancer post-exposure? That would represent a 20% increase. Not to minimize significance... but that doesn’t seem abundantly significant.