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Ionising radiation

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

Ionisierende Strahlung

Radon in the soil air in Germany

  • In Germany, radon concentrations in the soil vary regionally.
  • This is due to the fact that uranium and radium, during whose decay radon is formed, regionally occur in different concentrations and that the soil's permeability to radon also varies regionally.
  • The BfS has created maps depicting the regional distribution of radon in the soil. No information on single buildings can ever be gained from the forecast maps but have to be measured in the respective building.

During the decay of uranium and radium, different amounts of which occur in all soils and rocks, radon is formed which propagates in the soil, finally reaching the surface.

As a result of leaks in a building, radon can get into the interior of buildings, accumulate there and cause lung cancer.

Measurement values and prognoses

How well radon can propagate in the soil, depends on its permeability to gas. Based on measurement values

  • of the radon concentration in the soil air,
  • the soil's permeability to gas
  • and by means of geological maps

the Federal Office for Radiation Protection (BfS) has developed prognoses for the regional distribution of radon in the soil air. The maps

  • "Radon concentration in the soil" and
  • "Radon potential"

show in a coarse grid how much radon occurs in the soil or, respectively, to what extent radon can be released from the soil.

Map "Radon concentration in the soil"

The map "Radon concentration in the soil" shows in a coarse grid how much radon occurs in the soil. Thus, it provides orientation as to the regional distribution of radon in the soil air one metre below the earth's surface.

Map of Germany with presentation of the radon activity concentration in the soil air Radon mapSurvey of radon concentrations in the soil air in Germany

Estimate by representative measurement data

The map is based on data from measurements at altogether 2,346 geologically representative measurement points in Germany that took place between 1992 and September 2003. In areas where an enhanced radon concentration has to be expected due to their geological characteristics, the measurement points were located closer together than in the other regions.

With the help of the 2,346 measurement data distributed over Germany, the Federal Office for Radiation Protection estimated the radon concentration in the soil for the whole of Germany. The map shows the estimates determined for a grid of three by three kilometres.

Radon situation in situ can only be clarified by measurements

The map does not provide information about the radon concentration in the soil air at a given location (such as a building plot) - nor about the concentrations in a single house.

The radon situation in an existing building can only be determined by measuring the radon concentration indoors.

Specialist application BfS Geoportal shows radon concentration in the soil

The estimates of the radon concentration in the soil air determined for a grid of three by three kilometres, can also be accessed via the BfS Geoportal specialist application.

By opening the complex map application, you need to close the welcome screen. With the help of the magnifier icon at the top right you can zoom in and out of the map.

"Radon Potential" map

The amount of radon escaping from the soil and potentially entering the interior of houses, is referred to as "radon potential". The level depends on how much radon is concentrated in the soil and how permeable the soil is to gas. The "Radon Potential" map therefore also considers the soil’s permeability, in addition to the radon occurrence in the soil.

Prognosis of radon potential in Germany shown in a map Prognosis of radon potential in GermanyPrognosis of radon potential in Germany

Estimate by representative measurement data

Since not every square metre in Germany can be measured to determine its radon concentration and permeability to gas, the BfS has developed a method with the help of which the radon potential can be estimated for the whole German territory.

Between 1992 and 2001, the radon concentration in the soil and its permeability to gas were measured at approximately 3,700 measurement points in Germany. With the help of these values, the radon potential can also be estimated for the gaps between the measurement points.

For this purpose, the measured values were compiled in a map of Germany according to their geology. Subsequently, similar measurement results in neighbouring regions were combined into a single unit. By means of mathematical simulations, the resulting pattern was then analysed and refined for the gaps between the measurement points.

The method is based on procedures that are used in a similar form e.g. in resource exploration, where, based on only a few test drillings, conclusions are drawn e.g. regarding the metal content. In earthquake research, too, a potential earthquake risk of single regions is concluded from measurements and the knowledge of the geological condition of the subsoil.

Radon situation in situ can only be clarified by measurements

The "Radon Potential" map provides a first assessment of the radon situation in a region. The actual level of radon at a given location can only be determined precisely by measurements of the near-surface air or the radon concentration inside a building.

The maps show in a coarse grid the regional situation to be expected. The map does not provide information about single buildings or plots since there may be strong local variations in the parameters used for the prognosis.

The actual radon situation at a given location can only be determined precisely through measuring the radon concentration.

State of 2018.11.21

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