From the article:
“… radioactive cesium levels were unusually high …”
(More links are down below.)
– Scientists detect highest cesium levels in a year in Fukushima (Asahi Shimbun, July 4, 2013):
FUKUSHIMA–Radioactive cesium levels found in moss on a rooftop in downtown Fukushima exceeded 1.7 million becquerels, the highest levels detected in a year, researchers said.
Ryoji Enomoto, an associate professor at the University of Tokyo’s Institute for Cosmic Ray Research, who led the team, said radioactive cesium levels were unusually high in the samples collected.
The city is located more than 50 kilometers from the crippled Fukushima No. 1 nuclear plant.