Table 2.
Air doses measured at monitoring sites maintained by Fukushima Prefecture near the study area (μSv/h).
| Measurement date | Monitoring site (μSv/h) | Duration (days) | Mean accumulated dose (μSv) | |
|---|---|---|---|---|
| Iizaka tunnel | Ohzaso | |||
| Apr. 2011 | 1.1 | 1.2 | 30 | 828 |
| Aug. 2011 | 0.54 | 0.50 | 120 | 1498 |
| Feb. 2012 | 0.5 | 0.46 | 180 | 2074 |
| May 2012 | 0.51 | 0.35 | 90 | 1048 |
| Oct. 2012 | 0.44 | 0.34 | 150 | 1404 |
| May 2013 | 0.28 | 0.25 | 210 | 1336 |
| May 2014 | 0.18 | 0.22 | 365 | 1752 |
| May 2015 | 0.16 | 0.16 | 365 | 1402 |
| May 2016 | 0.10 | 0.13 | 365 | 1007 |
| Total | 12349 | |||
Mean accumulated doses were estimated to multiply the average value of air doses in two monitoring site by the number of days between consecutive measurement dates.