Radon map Federal Office for Radiation Protection
The radon map of the Federal Office for Radiation Protection estimates the regional occurrence of radon in homes, but the actual radon exposure in individual buildings cannot be accurately predicted. It is therefore a forecast and not an absolutely accurate statement about the radon levels in your individual rooms. For a professional assessment, it is necessary to measure the air component radon - using a radon measuring device or a one-off radon room air analysis.
Tip: You can find a zoomable map on the BfS geoportal.
Where in Germany is the radon concentration highest?
The radon map depicts strong regional differences and shows the average exposure of people in Germany in their homes. According to the BfS, there is a very high concentration of the radioactive gas in the low mountain ranges and the Alpine region, while exposure is rather low in north-western Germany.
The comparison between large cities and rural areas indicates that people in rural areas are exposed to more radon than in cities. Settlement structure characteristics therefore have an effect on the radon concentration. While single-family homes with a few storeys dominate in the countryside, in urban areas there are mainly apartment buildings and multi-storey buildings. As the gas rises from the ground, the exposure decreases the further the home is from the ground and increases the closer the living spaces are to the ground. In cities such as Berlin, Leipzig, Kassel, Hamburg, Regensburg or Erfurt, the radon map therefore indicates lower forecast values than in the surrounding areas of the cities.
What is the average radon concentration in Germany?
In living spaces, the average annual radon concentration is around 65 becquerels per cubic meter - this means that 65 nuclei of the radioactive substance decay per second. According to statistics, around 10.5 million people are exposed to a radon concentration of over 100 becquerels per cubic meter in their homes. Two million of them are even exposed to a concentration of over 300 becquerels per cubic meter. Values above 1,000 becquerels per cubic meter are rarely reached.
The radioactive gas radon
The Radiation Protection Act regulates protection against the noble gas and defines measures for areas with high radon levels. The Radiation Protection Act specifies 300 becquerels per cubic meter as the reference value for an increased concentration. Above this value, measures should be taken to reduce the gas in the building. The following applies:
- Owners of private, existing buildings can voluntarily initiate measures.
- Builders of new private buildings are obliged to avoid structural measures that facilitate the penetration of the gas.
- The reference value of 300 Becquerel per cubic meter averaged over the year prevails at the workplace; above this radon exposure level, there is an obligation to introduce measures to reduce it.
Regardless of the limit value, the lower the radon exposure, the lower the risk.
What is radon?
Radon is a gas that occurs naturally in the earth's crust . These properties characterize radon:
- colorless
- odorless
- Tasteless
- radioactive
Due to these properties, the noble gas is not perceived by the human senses. An appropriate measuring device or dosimeter is required to measure radon.
Radon is produced by the radioactive decay of uranium and thorium, which are present in rocks and soil materials. As the noble gas is particularly small and unbound, the particles migrate to the earth's surface and the radon easily escapes from the ground. Radon then enters the building through the smallest cracks and fissures in the concrete. While it is distributed outdoors and diluted with the fresh air to a harmless concentration, the particles indoors can accumulate to a level that is hazardous to health.
How dangerous is radon & what are the health effects?
As radon is a radioactive gas, there are health risks associated with breathing it in. If the radon nuclei decay while they are in the lungs, the resulting alpha particles can damage the alveoli and promote the development of lung cancer.
If people are exposed to increased radon levels over several years, the risk of lung cancer increases by approx. 16 % per 100 becquerels per cubic meter of indoor air. There is no lower threshold value that could be estimated as a harmless, safe concentration. This means that radon should generally be avoided. After smoking, the gas is the most common cause of lung cancer. It is therefore advisable to measure the radon concentration in living and working spaces and, if necessary, to take measures to reduce exposure.
How does radon get into buildings & the home?
The gas is found in some soils and penetrates into the building from the soil air of the building site. In addition to the soil, building materials and drinking and process water can also be a source of radon to a small extent. As the particles are extremely small, they even penetrate concrete, thus reaching all interior rooms and can spread here. In comparison, the concentration is highest near the floor, i.e. in the basement and on the first floor. However, radon may also occur on higher floors due to air circulation within the house.
How is the radon concentration in the home affected?
The concentration of the gas is influenced by various factors:
- Radon saturation with which the soil is enriched with radon: If the soil contains more radon, more gas can diffuse into the air.
- Composition & permeability of the soil: For example, sandy soils are more permeable than clay soils.
- Construction type of the building: Pressure differences between the interior of the building and the subsoil can lead to suction, which draws the radon into the interior. Pipe penetrations and leaks in the masonry and/or the floor slab also facilitate the penetration of the gas.
- Ventilation intensity & intervals: In closed, poorly ventilated rooms, the noble gas can accumulate to a concentration that is hazardous to health. Regular ventilation prevents the gas from accumulating in the room.
- Location of indoor rooms: The further away the room is from the building ground, the lower the radon exposure.
How do you protect your home against radon?
As radon atoms are extremely small, they cannot be filtered. To better protect yourself from radon in your home, you can prepare the building site accordingly and take radon exposure into account when building your house. You should pay attention to these points:
- Continuous base plate
- Modern moisture insulation & drainage
- Basement
- Sealing leaks in the foundation
- Improving ventilation with a ventilation system
- Reliable indoor measurement strategy to measure radon exposure
The most important point is correct ventilation. Radon-enriched indoor air must be exchanged for fresh air and the pollutant removed. Ideally, you should ventilate on demand when the air composition requires an air exchange. Air measuring devices such as the air-Q, which measure the radon and issue a warning if necessary, are suitable for this purpose.
In comparison: radon device vs. radon room analysis
In a radon room air analysis, the radon content in your rooms is measured over a period of one week. This gives you certainty as to whether and how much radon is present in your home or workplace. This is useful for private individuals as well as employees and employers. For continuous monitoring of the gas, it is advisable to purchase a radon measuring device.
With the air-Q radon sensor, you can not only measure localized radon exposure, but also constantly detect the air components and even identify other pollutants. The colored LED display shows you the development of the air quality and the radon concentration and warns you when an air exchange is necessary. With the air-Q web app, you can analyze all sensors and measured values on your PC and keep a detailed eye on the air components.
What do you know about radon? Take the quiz:
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