Table 2. Geometric mean levels of the annual additional doses from external exposure among children in Soma City.

	Year	2011	2012	2013	2014	2015
Whole, n		3,812	3,824	2,979	1,937	1,853
	Geometric mean dose (mSv/y)	0.60	0.37	0.22	0.20	0.17
	Geometric standard deviation	1.72	1.71	1.71	1.61	1.53
	ND, %	79 (2.1)	484 (12.7)	1,268 (42.6)	980 (50.6)	1,235 (66.6)
	More than 1 mSv/y, %	593 (15.6)	115 (3.0)	8 (0.3)	2 (0.1)	0 (0)
Zone 1, n		157	144	123	75	56
	Geometric mean dose (mSv/y)	0.82	0.58	0.29	0.27	0.21
	Geometric standard deviation	1.76	1.54	1.62	1.48	1.67
	ND, %	1 (0.6)	1 (0.7)	27 (22.0)	16 (21.3)	26 (46.4)
	More than 1 mSv/y, %	60 (38.2)	14 (9.7)	1 (0.8)	0 (0)	0 (0)
Zone 2, n		231	205	177	125	119
	Geometric mean dose (mSv/y)	0.93	0.60	0.34	0.29	0.22
	Geometric standard deviation	1.45	1.60	1.74	1.43	1.45
	ND, %	0 (0)	2 (1.0)	29 (16.4)	19 (15.2)	46 (38.7)
	More than 1 mSv/y, %	105 (45.5)	28 (13.7)	2 (1.1)	0 (0)	0 (0)
Zone 3, n		23	18	12	10	11
	Geometric mean dose (mSv/y)	2.53	1.59	0.74	0.60	0.40
	Geometric standard deviation	1.28	1.55	1.39	1.65	1.44
	ND, %	0 (0)	0 (0)	0 (0)	0 (0)	0 (0)
	More than 1 mSv/y, %	23 (100)	16 (88.9)	3 (25.0)	1 (10.0)	0 (0)
Zone 4, n		26	27	22	7	8
	Geometric mean dose (mSv/y)	0.83	0.59	0.42	0.35	0.29
	Geometric standard deviation	1.35	1.38	1.55	1.37	1.50
	ND, %	0 (0)	0 (0)	1 (4.5)	0 (0)	1 (12.5)
	More than 1 mSv/y, %	3 (11.5)	2 (7.4)	0 (0)	0 (0)	0 (0)
Other areas, n		3,375	3,430	2,645	1,720	1,659
	Geometric mean dose (mSv/y)	0.57	0.35	0.21	0.19	0.16
	Geometric standard deviation	1.69	1.67	1.64	1.59	1.48
	ND, %	78 (2.3)	481 (14.0)	1211 (45.8)	945 (54.9)	1162 (70.0)
	More than 1 mSv/y, %	402 (11.9)	55 (1.6)	2 (0.1)	1 (0.1)	0 (0)

Zones 1, 2, 3, and 4 correspond to Yamakami, Yawata, Tamano districts and the Akagi area of Nittaki-district in Soma City, respectively.