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Ionising radiation

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

Ionisierende Strahlung

Radioactive substances in building materials

Radioactive substances in building materials can be of natural origin. Radon is particularly relevant in this context. Naturally occurring radioactive substances accumulate in several residues from industrial processes. Some of them are used as secondary raw materials in the building and construction industry.

Building material: paving stones

Radionuclides in building materials

Radionuclides in building materials cause radiation exposure through the emission of gamma radiation and the inhalation of radon released in rooms. The mean value of the gamma local dose rate (ODL) in buildings caused by the natural radionuclides in building materials is about 80 nanosievert per hour. ODL values above 200 nanosievert per hour are rare. The building materials traditionally used in great quantities in Germany, are generally not the cause for enhanced radiation exposures due to radon in buildings.

Radon in Granite

In the past, newspapers reported about granite in homes as a source of potential radiation exposure. Natural stone and other building materials contain the natural radionuclides uranium-238, thorium-232 and their decay products as well as potassium-40. As an intermediate of the uranium-238 decay chain, the radioactive noble gas radon-222 (Rn-222, half life 3.8 days) originates from radium-226. However, in most instances the proportion of radon from building materials and natural stone in homes is small compared to the amount of radon emitted from soil. Radon is a colourless, odourless and tasteless radioactive noble gas. Part of the radon occurring indoors is emanated from building materials.

Interior with clay plaster

Radon in clay

Common mineral house building materials such as concrete, brick, gypsum and aerated concrete contain natural radionuclides. It is currently a matter of debate whether unfired clay building materials may result in radiation exposures critical to health. Unlike radon of which both the occurrence in buildings and health effects have been studied well, thoron requires further research to facilitate a reliable evaluation of its health implications.

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