UPDATE: Japanese officials say elevated levels of radiation found in Tokyo and Yokohama are not related to the Fukushima nuclear crisis, BBC reports. Japan's science minister announced Thursday that the radiation has been "traced to material stored in the basement of a house," it states.
Japanese officials say they have detected elevated levels of radiation in a residential area of Tokyo, and in Yokohama.
Bloomberg reports that more tests are being run after a pike in radiation readings pointed to “hotspots” being formed as a result of fallout from the Fukushima nuclear disaster.
The Tokyo hotspot is in Setagaya ward, in the city's west, which has a population of more than 840,000 people. It is located 124 miles from the Fukushima plant, which was damaged by a tsunami in March.
Authorities will run tests in in 258 locations, after a concerned resident reported a high radiation reading of 2.7 microsieverts per hour in the Tsurumaki 5-chrome area.
The 2.7 microsieverts an hour equates to a dose of 14.2 millisieverts per year, or more than 14 times the internationally recommended level for the general public, according to a Science Ministry formula.
That reading is higher than several areas within the 20-kilometer exclusion zone around the crippled Fukushima nuclear plant that was evacuated by the government, according to Science Ministry data.
The discovery led authorities to partially block off a sidewalk, which is to be decontaminated. The Kyodo news agency said the route is regularly used by school children.
Michio Hirasawa, a spokesman for Setagaya ward, told Bloomberg the readings were found in a very small area “and we will take measures to resolve residents’ concerns”.
But Ban Hideyuki, co-director of the Citizens’ Nuclear Information Center, said the readings came as a surprise, and prove that government surveys can miss small hot spots - “and surveys by citizens are needed to find them.”
(Read more on GlobalPost: Japan to give radiation meters to children living near Fukushima plant and Fukushima cesium "equals 168 Hiroshimas")
According to The Japan Times, the discovery in Setagaya comes after reports that high levels of strontium-90, which is linked to leukemia, had been found on a rooftop in Yokohama.
Yokohama is located some 250 km from Fukushima. The paper said that if the substance is found to have come from Fukushima, it will be “the first time strontium at a concentration of more than 100 becquerels per kilogram has been found beyond 100 kilometers from the troubled plant”.
The strontium-90 was reportedly detected by a private agency that had been carrying out tests at the request of a resident.