impact on human health. they also said that they expect these levels of radiation, these venting of radiation particles into the atmosphere would be continuing for some time. how to piece this all together, how to give it context, involves give looking at what the radiation is and how high the doses are. 400 millisieverts, keep in mind this is one of the highest readings that was found today near one of the reactors. typically just walking around, living in most countries in the world, you re going to get a certain amount of background radiation, a few millisieverts a year. if you get a chest x-ray, a few more millisieverts, a c.a.t. scan, a couple hundred. here we re talking about 400 millisieverts that was actually within the plant. adds it starts to move outside the gates, some of that will decay, some disperse and people 20 to 30 kilometers away will as a result get a pretty low dose