Originally Posted by sxf24

At this point, you're probably exposed to more radiation in flight than you are at NRT.

The State Department's warnings have not been as strongly worded as you suggest ("urging to defer travel") and (outside of the Fukushima Daiichi evacuation zone) is not based on possible radiation exposure.

I agree that leaving the airport in Japan should be avoided right now. However, there's really no risk for transiting passengers right now.