TOKYO (Dow Jones)–Japanese researchers have discovered high levels of radioactive material in concentrated areas in Tokyo and Yokohama, more than 241 kilometers away from the Fukushima Daiichi nuclear plant, as increasingly thorough tests provide a more disturbing picture of just how far contamination has spread and accumulated after the March disaster.
In Tokyo, a sidewalk in Setagaya Ward in the western part of the city recorded radiation levels of 2.707 microsieverts per hour, about 50 times higher than another location in Setagaya where the ward regularly monitors radiation levels.
In Yokohama, the local government said last month that it detected 40,200 becquerels of radioactive cesium per kilogram of sediments collected from one part of a roadside ditch.
By comparison, the Japanese government has banned cultivation of rice in fields found to have more than 5,000 becquerels of cesium per kilogram of soil.
Yokohama is currently investigating another spot on an apartment rooftop where tests conducted by a local private research institute detected more than 60,000 becquerels of radioactive cesium per a kilogram of sediments.
Both Setagaya Ward and Yokohama discovered those concentrated spots after local residents carrying their radiation measuring devices noticed such spots and reported it to local officials.
In the roadside ditch where 40,200 becquerels were detected, another spot in the same ditch recorded only 3,030 becquerels.
“We’ve always known that there are ‘hot spots’ where contamination levels are higher than other areas, but these tiny spots are like ‘micro hot spots’,” said John Kuramochi, who heads the section of the Yokohama city government in charge of monitoring contamination.