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Ionising radiation

Environmental Radioactivity - Medicine - Occupational Radiation Protection - Nuclear Hazards Defence

Ionisierende Strahlung

Where does radioactivity occur in the environment?

  • Radionuclides are found everywhere in the environment.
  • In principle, every individual on earth is naturally exposed to ionising radiation. Nobody can avoid it.
  • It arises from naturally occurring sources present in nature, independent of human activity.

In many people, the term "radioactivity" elicits unease. The ionising radiation emitted from radioactive substances is often considered threatening - no matter how strong it is or where it comes from.

In principle, every individual on earth is naturally exposed to ionising radiation. Nobody can avoid it. It arises from naturally occurring sources present in nature, independent of human activity.

When an individual is exposed to ionising radiation, we speak of radiation exposure or radiation burden.

Natural radiation exposure

Natural radiation exposure comprises internal and external components. The internal component constitutes the main part of natural radiation exposure. It accounts for two thirds of the total natural radiation exposure, the external component for one third.

Internal radiation exposure

Through breathing air and eating food, people have always taken up natural radionuclides into the body. In addition, radionuclides can enter the body through open wounds.

Intake through breathing

The largest proportion of natural radiation exposure stems from inhaling the radioactive noble gas radon and its decay products. The radiation exposure from radon results in an average annual dose of 1.1 millisieverts.

Further information can be found in the section on radon.

Intake through food

Through food, natural radionuclides from the radioactive decay chains of thorium and uranium, as well as potassium-40 are absorbed; on average this adds 0.3 millisievert per year.

Further information can be found in the section on radioactivity in foods.

External radiation exposure

External radiation exposure amounts to 0.7 millisievert per year.

Cosmic radiation

A substantial part of the ionising radiation people are exposed to, originates from cosmic radiation. It reaches the earth from the sun and from deep space and is mainly composed of high energy particles and gamma radiation. On its way through the atmosphere, cosmic radiation is partially absorbed. Thus, the intensity of cosmic radiation depends on altitude. It is lowest at sea level and increases with the altitude of a site. On the Zugspitze it is four times higher than at the coast. Airplanes cannot be shielded against cosmic radiation. Thus, people are exposed to this type of radiation during a flight.

Further information can be found in the section on radiation exposure of airline passengers and in the section on monitoring of aircraft crews.

Terrestrial radiation

Terrestrial radiation is a further component of the external radiation exposure. It arises from natural radioactive substances present in soils and strata of the Earth's crust and differ vastly across different regions.

On average, the annual effective dose due to terrestrial radiation in Germany amounts to 0.4 millisievert, about 0.1 millisievert of which is attributed to the time spent outdoors and about 0.3 millisievert to the time spent indoors.

Radioactive substances in building materials

Rocks and soils are important resources for mineral building materials, such as bricks and concrete. The radionuclides present in the rocks pass into the building materials and in this way add to the external radiation exposure.

Further information can be found in the section on building materials.

Natural radiation exposure in Germany

The total natural radiation exposure in Germany amounts to 2.1 millisieverts per year on average (effective dose). Depending on the place of residence, dietary and lifestyle habits, it ranges from 1 to 10 millisieverts.

Exposure due to artificial sources of radioactivity

Artificial radionuclides in the environment make you think of reactor disasters as they occurred in Chernobyl and in Fukushima. However, artificial radionuclides were also released during nuclear weapons tests. Small amounts of radionuclides are released from nuclear installations during normal operation as well. The release is strictly monitored by various measuring networks.

Further information can be found in the section on IMIS.

State of 2017.05.02

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