The Japanese earthquake and tsunami caused a severe event at the Fukushima Nuclear Plant. At the University of Washington Physics Department we rapidly adapted one of our basic research labs to monitor for the arrival of trace amounts of fission products produced at Fukushima. On Friday, March 18, we detected the first trace amounts of radioactive isotopes from Fukushima in Seattle. We stress that the overall amount of the radioactivity is extremely low, at least thousands of times below EPA limits. For all of the details, see our recent article on the arXiv!
Here are the most recent data
And a clear arrival peak of 131-I in the data