there's been no specific studies done to say this is the absolute size of the evacuation zone. it should be this size based on these readings. some of it is based on weather conditions, wind conditions and things like that. it's safe to say the u.s. recommendations are more conservative. they're saying we need a farther evacuation zone. keep in mind with that 20 kilometer evacuation zone you had hundreds of thousands, 200,000 some residents who are essentially displaced adding to the displacement of the people affected by the tsunami. this is compounding those two problems. as far as the differing numbers, i said almost since the beginning there's an arbitrary nature to this and this is another example of that. >> there's a lot of fears about the radiation cloud, the jet stream is going to be blowing this to the west coast of america. how concerned will we be when it comes this way? will most of the radiation be dissipated?