The problem is not the radiation in the air in this is particular accident. The Fukushima reactor(s) won't go boom and blow up a cloud of radioactive particles, as Spectre has already explained long ago. So the chart is rather meaningless.
The radiation will, however, be disastrous for the nearer vicinity and -- if the core really melts itself into the ground -- for the soil and the ground water, especially, since reactor 3 (the most critical one at the moment) contains those nasty MOX fuel rods, which contain plutonium. Since no "all clear" signal has been given yet and the official statements still speak of "slight problems" or "bit of damage" but never saying everything is under control, it has to be assumed the whole thing is still pretty much out of control.
People are making the mistake of believing that now the worst part is over, since it didn't go boom. But that's a misbelief. It is clear by now, that an efficient cooling of the rods doesn't take place, that the meltdown is probably still in process. This isn't a fast process, you know. Leave those fuel rods to themselves and they will generate heat and radiation for years to come.
There will be no danger for the wider region (except some really terrible still happens, like a steam explosion or so) but the area around the Fukushima facility will be uninhabitable for some time and there will be quite some contamination of the ground, the water, the plants. I don't know, where the ground water at Fukushima goes to, if for example it ends up in a river or in the sea (which both would contaminate an even wider area) but the least people around Fukushima should expect, is a raising rate of cancer in the future, especially among children.
Welcome to the nuclear age.