Dr. Tsubokura's Radiation Lecture Vol.17

Author: Masaharu Tsubokura

Editors: Akihiko Ozaki M.D., Yuki Senoo

33. Radiation exposure in Eastern Japan is little different from that in Western Japan

It has been almost four and a half years since the Fukushima Daiichi nuclear accident (the publication date of the original article was August 23, 2015).

The air radiation dose rate has been gradually decreasing year by year; the air radiation dose rate in Soma City in 2015 fell by 70% compared to that of June 2011. However, the air dose rate will never reach zero due to the naturally occurring radiation emitted from radioactive agents in the universe or rocks and concrete in our living environment.

The level of naturally occurring radiation varies between regions in and outside of Japan. Initially, the region to the west of Fossa Magna—the north-south spot that geologically divides Japan in two—had a higher air radiation dose rate than the region to the east of Fossa Magna. One reason for this is that the distribution of granite (Kakougan) differ