Radiation from Fukushima - Map from Norwegian Institute of Air Research
Full mid levels of Cesium , Xenon, and Iodine.. particulate matter, in the cloud vapor from surface level to 5000m (15,000 feet) ..
It is up to you to decide how you want to approach this data.
Personally, I believe it to be IN THE PRECIPITATION for sure.. which means you do not want to get the rain or snow on you, and do not want to injest the fluid.. (i.e. drink the water) until levels deminish.
Read more: Radiation Spreads throughout the Northern Hemisphere