title: Indoor radiocaesium contamination in residential houses within evacuation areas after the Fukushima nuclear accident.
abstract: Indoor contaminants were investigated from July 2013 to January 2015 within ninety-five residential houses in five evacuation zones, Iitate village, Odaka district, and the towns of Futaba, Okuma, and Tomioka. A dry smear test was applied to the surface of materials and structures in rooms and in the roof-space of houses. We found that (134)Cs and (137)Cs were the dominant radionuclides in indoor surface contamination, and there was a distance dependence from the Fukushima Daiichi nuclear power plant (FDNPP). For surface contamination in Iitate village (29-49 km from the FDNPP), 24.8% of samples exceeded the detection limit, which is quite a low value, while in Okuma (<3.0 km from the FDNPP), 99.7% of samples exceeded the detection limit and surface contamination levels exceeded 20 Bq/cm(2) (the value was corrected to March 2011). In residential houses in Okuma, Futaba, and Tomioka, closer to the FDNPP than those in Odaka district and Iitate village, surface contamination was inversely proportional to the square of the distance between a house and the FDNPP. In the houses closest to the FDNPP, the contribution of surface contamination to the ambient dose equivalent rate was evaluated to be approximately 0.3 μSv/h.
authors.affiliation: Graduate School of Pharmaceutical Sciences, Tohoku University, 6-3 Aramaki-Aoba, Aoba-ku, Sendai, Miyagi 980-8578, Japan.
authors.forename: Hiroko
authors.initials: H
authors.lastname: Yoshida-Ohuchi
authors.affiliation: Graduate School of Pharmaceutical Sciences, Tohoku University, 6-3 Aramaki-Aoba, Aoba-ku, Sendai, Miyagi 980-8578, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Kanagami
authors.affiliation: Advanced Industrial Science and Technology, 1-1-1 Umezono, Tsukuba, Ibaragi 305-8568, Japan.
authors.forename: Yasushi
authors.initials: Y
authors.lastname: Satoh
authors.affiliation: Department of Radiological Life Sciences, Hirosaki University Graduate School of Health Sciences, 66-01 Hon-cho, Hirosaki, Aomori 036-8564, Japan.
authors.forename: Masahiro
authors.initials: M
authors.lastname: Hosoda
authors.affiliation: Japan Environment Research Co., Ltd., 02-15-1 Hon-cho, Aoba-ku, Sendai, Miyagi 980-0014, Japan.
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Naitoh
authors.affiliation: Japan Environment Research Co., Ltd., 02-15-1 Hon-cho, Aoba-ku, Sendai, Miyagi 980-0014, Japan.
authors.forename: Mizuki
authors.initials: M
authors.lastname: Kameyama
mesh_terms: D000398:Air Pollution, Radioactive / Q000032:analysis*; D002588:Cesium Radioisotopes / Q000032:analysis*; D004784:Environmental Monitoring; D062406:Fukushima Nuclear Accident; D011834:Radiation Monitoring / Q000379:methods*
chemical_list: D002588:Cesium Radioisotopes