A group of Tokyo parents filed a request Tuesday asking the metropolitan government to change the way it determines radiation levels in the capital after their own study found relatively high levels of contamination around Koto Ward.
"No! Hoshano Koto Kodomo Mamoru Kai" ("No! Radioactivity — The Group to Save Children in Koto") found that some areas in Koto Ward, located in the eastern part of the capital, had a maximum hourly reading of 0.18 microsievert of radiation.
That number is a fraction of the level in Fukushima Prefecture, which hit about 1.6 microsieverts per hour on Tuesday.