Contamination due to radioactive materials around the metropolitan area in Japan

The reactor accident of Fukushima Daiichi Power Plant of Tokyo Electric Company due to the East Japan Earthquake of March 11, 2011, emitted radioactive substances including such as cesium 137, 134 and iodine 131 which deposited on a vast area around Metropolitan. The contamination map was made based on environment monitoring from airplanes reported by Ministry of Science and Technology. Radioactivity of soils at the ground surface in metropolitan area amounts to 10 kBq/m2 at the highest level, radioactivity distribution being mentioned. Time variation and spatial (local) distribution of air dose rate are reported. Furthermore, some examples of guiding principles which are proposed by local government for appropriate countermeasures are presented. (S. Ohno)