The chart is useless due to the metrics used.
http://www.whoi.edu/main/topic/fukushima-radiation
From the article:
“The scientists found elevated levels of the nuclear by-product cesium but they were below the threshold of concern for direct human exposure. The levels of cesium had diminished quickly off shore because cesium is soluble in seawater and was therefore diluted by the Pacific ocean currents.”
It also speaks of folks on the West Coast of America breathing in “hot particles”. I’m assuming that would mean alpha-emitters? One of the big problems with determining dangers is the withholding of data from the government who in all likelihood, after years and years of study and billions spent, knows but is hindered by bureaucrat channels from releasing.