(i) Radiation around us
We are exposed to radiation in our daily lives without realizing it. In addition, there are natural radioactive materials contained in the human body and common foods.
Measurement results for ambient dose rates in major cities
- Source:
- Prepared based on data by the Japan National Tourism Organization
(https://www.japan.travel/en/news/post-2011-3-11-general-information/, as of December 2018)
This figure shows ambient dose rate measurements for major cities in Japan and other parts of the world in 2017 or 2018. Radiation dose can be seen to vary by region. This is due to variations in the amount of ground radiation, mainly caused by differences in soil and rock composition.
Natural radioactive materials in the human body and foods
As shown in the figure to the left, the human body and common foods contain radioactive materials. Potassium is an essential element for life, and because 0.01% of potassium is radioactive, most foods contain radioactive potassium. Radioactive potassium emits β-particles and γ-rays, causing internal exposure from food intake. The internal potassium concentration is held constant, so exposure doses from potassium in foods depend on individuals’ physiques and are considered unaffected by diet.
- Source:
- Prepared based on “Research on Data about Living Environment Radiation (1983),” Nuclear Safety Research Association
For more information about natural radioactive materials, see page 73 of Vol. 1, FY2022 edition.
