Familiar type of radiation

Natural radiation

There are many radioactive materials in nature and we are exposed to various kind of radiation everyday. Such radiation is called "natural radiation."

Radiation from space

Much radiation is traveling through space, some of which comes to the surface of the earth. This radiation which comes from the universe is called "cosmic rays."

When we are outdoors, we are always being exposed to cosmic rays because cosmic rays can penetrate directly from outside of the body like a gamma rays. Most cosmic rays are interrupted by the atmosphere which covers the surface of the earth. But since the atmosphere is thin, the amount of exposure to cosmic rays also increases at high elevations.

Moreover, high up in the sky, nuclear reactions occur when cosmic ray particles collide with the atmosphere and various kind of radiation are produced. Some of this radiation reaches on the ground.

Radiation from the air

Gasses called radons which exist in the air in small quantities is also give off radiation.

The radiation from the ground

We also receive radiation also from the ground because radioactive material is also contained there.

For example, radioactive material is contained in the granite used for gravestones, etc. Therefore, in the Kansai district,which has a higher rate of subterranean granite than the Kanto district, the quantity of natural radiation is a little higher.

In other are as, the quantity of natural radiation becomes higher in land with many radioactive elements, such as uranium, radium, and thorium, contained in their geology.

Moreover, as for doses of radiation, indoors is sometimes higher than outdoors because radioactive material is also contained in concrete and other substance which are used in buildings. Of course, if it is the wooden building and other radiation sources cannot be found, a dose of radiation inside will become lower.

Radiation inside living things and food

A plant and an animal take in an inorganic substances into their bodies, in order to live.Radioactive material may be contained in these inorganic substance.

For example, potassium is required in order humans,animals, and plants to live, but potassium　has the isotope called "potassium 40". That is, when we eat a meal, we may be ingesting and accumulatiny potassium and potassium 40 into out bodies. But the amount inside the body is kept almost constant because such radioactive material's radioactivity weakens over time is passes out ok the body metabolism.

In addition topofussiurm,other radioactive materials taken into the body meals "carbon 14" and "lead 210".