The Mainichi Daily News has reported that the Koirino district of the town of Okuma, 3 km from the shattered Fukushima Daiichi nuclear power plant, has an annual radiation dose rate higher than 500 millisieverts (50 rem) -- a whopping 500 times the "allowable" exposure level permitted under ordinary, pre-catastrophe circumstances. One radiobiologist described such a high radiation field as exceeding "the amount that astronauts are exposed to during long stays on the International Space Station," and concluded it would be very difficult to decontaminate. Another area, the Kawabusa district of the town of Namie, registers 223.7 millisieverts (22.4 rem) per year; it is located 20 km northwest of Fukushima Daiichi, at the very edge of the exclusion zone, meaning residents could legally live very close by, despite such high risks.