title: Impact on ambient dose rate in metropolitan Tokyo from the Fukushima Daiichi Nuclear Power Plant accident.
abstract: A car-borne survey was made in metropolitan Tokyo, Japan, in December 2014 to estimate external dose. This survey was conducted for all municipalities of Tokyo and the results were compared with measurements done in 2003. The ambient dose rate measured in the whole area of Tokyo in December 2014 was 60 nGy h(-1) (23-142 nGy h(-1)), which was 24% higher than the rate in 2003. Higher dose rates (>70 nGy h(-1)) were observed on the eastern and western ends of Tokyo; furthermore, the contribution ratio from artificial radionuclides ((134)Cs and (137)Cs) to ambient dose rate in eastern Tokyo was twice as high as that of western Tokyo. Based on the measured ambient dose rate, the effective dose rate after the accident was estimated to be 0.45 μSv h(-1) in Tokyo. This value was 22% higher than the value before the accident as of December 2014.
authors.affiliation: Department of Radiological Sciences, Graduate School of Human Health Sciences, Tokyo Metropolitan University, 7-2-10 Higashiogu, Arakawa-ku, Tokyo 116-8551, Japan. Electronic address: kzminoue@tmu.ac.jp.
authors.forename: Kazumasa
authors.initials: K
authors.lastname: Inoue
authors.affiliation: Department of Radiological Sciences, Graduate School of Human Health Sciences, Tokyo Metropolitan University, 7-2-10 Higashiogu, Arakawa-ku, Tokyo 116-8551, Japan.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Tsuruoka
authors.affiliation: Department of Radiological Sciences, Graduate School of Human Health Sciences, Tokyo Metropolitan University, 7-2-10 Higashiogu, Arakawa-ku, Tokyo 116-8551, Japan.
authors.forename: Tan
authors.initials: T
authors.lastname: Van Le
authors.affiliation: Department of Radiological Sciences, Graduate School of Human Health Sciences, Tokyo Metropolitan University, 7-2-10 Higashiogu, Arakawa-ku, Tokyo 116-8551, Japan.
authors.forename: Moeko
authors.initials: M
authors.lastname: Arai
authors.affiliation: Department of Radiological Technology, Faculty of Health Sciences, Nihon Institute of Medical Science, 1276 Shimogawara, Moroyamamachi, Irumagun, Saitama 350-0435, Japan.
authors.forename: Kyoko
authors.initials: K
authors.lastname: Saito
authors.affiliation: Department of Radiological Sciences, Graduate School of Human Health Sciences, Tokyo Metropolitan University, 7-2-10 Higashiogu, Arakawa-ku, Tokyo 116-8551, Japan.
authors.forename: Masahiro
authors.initials: M
authors.lastname: Fukushi
mesh_terms: D000396:Air Pollutants, Radioactive / Q000032:analysis*; D002588:Cesium Radioisotopes / Q000032:analysis*; D062406:Fukushima Nuclear Accident; D011834:Radiation Monitoring; D014041:Tokyo
chemical_list: D000396:Air Pollutants, Radioactive; D002588:Cesium Radioisotopes
keywords: Ambient dose rate; Annual effective dose; Car-borne survey; Dose rate distribution map; Metropolitan Tokyo