http://ex-skf.blogspot.com/#Fukushima I Nuke Plant: Charts Showing Release of Radioactive Iodine and Cesium into Air May Be Going Up Again
Found them @Physics Forums, posted by clancy688 today. The poster doesn't link to the original site where the charts came from. Labels are in German, so they could be from DWD (Deutscher Wetterdienst), as CTBTO does not have a mandate to disclose the data.
CTBTO stands for "Comprehensive Test Ban Treaty Organization", and "38" is their Takasaki Station in Gunma Prefecture in Japan.
It looks as if something had happened around April 18, and both cesium 137 and iodine-131 are on the rise again in a volatile fashion in Japan. The US West Coast is following suit. MORE AT LINK
I do not know and do not guarantee the authenticity of the charts.
Unit is becquerels in cubic meter, and the red dotted line indicates the highest daily amount in Germany (May 1, 1986 in Bavarian Forest) during the Chernobyl accident.