You guys are loving handicapped
1- You cant breath in radiation (Unless you are breathing in radiated dust/particles)
2- America is stupid as forget to believe that they are more worried of radiation hitting the US over Japan
3- Even IF the nuclear reactors in Japan becomes another Chernobyl (I.E. loving handicaps doing stupid stuff they shouldn't be doing and poorly designed reactors) and a cloud of radiation does happen, it will NOT reach America, at most it will BARELY reach China and even if the jet-streams push the particles (Like it did in Chernobyl) we will have such a barely noticeable amount of radiation, its like if you sat through a plane trip.
Seriously... Take off your lead underwear and helmet already and hope for the best.