Nuclear cloud trajectory Northern Hemisphere Xe-133

Xe-133 is a fission product used in medicine for imaging purposes in lungs and brain.
It is radioactive and decays emitting beta and gamma emissions and decays to Cs-133 its half life is 5.243d. It is made by fission of uranium 235. Health effect of chronic exposure: cancer, leukemia, genetic and teratogenic effects.

Right now the whole continent of N. America is under a blanket of X-133.