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Ionising radiation

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

Ionisierende Strahlung


Diagram of radon pathways from the soil to the surface Radon pathways

Radon is a very mobile, radioactive noble gas that cannot be seen, smelled or tasted. It is a result of the radioactive decay of uranium. Uranium, for example, exists in the ground or in building materials.

From the ground, radon enters the atmosphere and buildings. Outdoors, it immediately mixes with the ambient air, so that the radon concentration there is low. Indoors, however, high radon concentrations can be reached.

Breathing an enhanced amount of radon and its radioactive decay products over a longer period of time increases the risk of getting lung cancer. It is often sufficient to take small measures to clearly reduce the radon content and thus the risk of disease.

The Radiation Protection Act commits the state, employer, and developers to take measures for the protection against radon.

Diagram of the radon decay chain

What is radon?

Radon is formed from natural uranium in the ground and in rocks and can accumulate in buildings, increasing the residents' lung cancer risk. Radon is a very mobile, radioactive noble gas occurring everywhere in the environment. During its decay it emanates radiation. According to recent findings, five to ten per cent of the lung cancer cases in the German population can be attributed to the exposure to radon in buildings. Thus, radon is the second leading cause of lung cancer.

A map of Germany

What is the spatial distribution of radon in Germany?

In Germany, there are regional differences in the amount of radon in the soil, in the air and indoors. In the North German Plain, radon concentrations are mostly low; in most low mountain ranges, in the Alpine foreland and in regions with moraines of rock from the last ice age they are rather high. The BfS provides maps on the regional distribution of radon in soil, indoors and outdoors. No information about single buildings or plots can be derived from the forecast maps.

Drawing of radon inside the lung

Health effects

The health risk due to radon is not so much due to radon itself but to its short-lived radioactive decay products. The radon decay products contained in breathing air (radioactive isotopes of the elements polonium, bismuth, and lead) deposit in the respiratory tract where they decay completely. This process produces high-energy alpha-radiation which may damage the cells, thus promoting the development of lung cancer.

Diagram of radon occurrence

Where does radon occur?

In different concentrations, radon occurs everywhere in our environment. From the underground of buildings radon also gets indoors, where it can accumulate. In particular when houses are only ventilated occasionally, this may lead to high radon concentrations that are dangerous to health. The radon concentrations in the ground, in the air, and indoors vary locally and regionally.

Protection against radon entering buildings

How can I protect myself from radon?

In the event of too much radon indoors, the first measure would be regular and intensive airing of the rooms. Since high radon concentrations generally occur from radon-containing soil air entering the rooms from the subsoil, new buildings should be waterproofed against soil moisture and leaks in existing buildings should be identified and removed.

Symbol of radon regulations

Provisions for buildings and workplaces

Protection from radon and its risks for health are regulated in Radiation Protection Act and in the Radiation Protection Ordinance. Their aim is to prevent as far as possible or to significantly impair the entry of radon into buildings, in particular in areas where a high radon concentration can be expected in many buildings. Protection provisions apply in these areas and these are different for residential buildings and workplaces. Under Radiation Protection Act, a reference value provides a standard for the suitability of protection measures.

© Bundesamt für Strahlenschutz