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Basics of Ionizing Radiation

Radiation in Our Daily Lives

Space

Radiation from SpaceThe universe is believed to have been born from “Big Bang” that occurred approximately 13.8 billion years ago.
Ionizing radiation known as “cosmic rays” has been traveling around the universe in great numbers ever since the creation of the universe.
Even now, radiation from space reaches the Earth from shining stars, the sun, and other sources.

Earth

Radiation from the Earth
Since the Earth was born approximately 4.6 billion years ago, there have been materials on the Earth that emit radiation (radioactive substances), and living things were born and have evolved in such an environment.
Granite near ground emits weak radiation. Even now, in the Earth’s interior, soil and rocks near the surface contain various radioactive substances.
The level of radiation tends to be slightly higher in Western Japan than in Eastern Japan as the region has more granite that contains a lot of radioactive substances.

Air

Radiation from Air
Granite, concrete, and others contain a radioactive substance called “radon.” Radon is a gas and escapes into air.
In places with little ventilation, such as concrete basements and stone houses, radon levels increase, increasing the radiation amount.

Food

Radiation from Food
Potassium, along with nitrogen and phosphorus, is one of the three major nutrients required for plant growth. We intake potassium by eating vegetables and other foods. This element is needed in our bodies for building muscles, etc.
Potassium contains a very small amount of radioactive material. Because we intake potassium through food, ionizing radiation is constantly being emitted from our bodies.