Changes in Air Dose Rate with Time Series Variations on the Mountain Trails of Mt. Takahara

Abstract

The purpose of this study was to clarity change in air dose rate with time series variations on the mountain trails of Mt. Takahara from October 2011 to November 2015. The air dose rates at a height of 1m in November 2015 were 0.3-0.4 times lower than those in October 2011. At investigation sites, the air dose rates decreased with natural decay, and were less than 0.23 μSv/h in November 2015, in endemic spruce, where the air dose rate was higher than that at other sites. This suggested that aerial radioactive materials were trapped on the canopy of the endemic spruce through cloud water deposition. During a hike to Mt. Takahara, the level of radioactive exposure was 0.001 mSv, and it returned to daily life in November 2015.