We have observed fallout from the recent Fukushima Dai-ichi reactor accident in samples of rainwater collected in the San Francisco Bay area. Gamma ray spectra measured from these samples show clear evidence of fission products - 131,132I, 132Te, and 134,137Cs. The activity levels we have measured for these isotopes are very low and pose no health risk to the public. © 2011 Norman et al.
Norman, E. B., Angell, C. T., & Chodash, P. A. (2011). Observations of fallout from the fukushima reactor accident in San Francisco bay area rainwater. PLoS ONE, 6(9). https://doi.org/10.1371/journal.pone.0024330