Radon Concentration Radiation Protection Icon

Radon (Rn)

Radon is a noble gas whose decay releases radioactive particles (so-called alpha radiation).

Can be measured with:

✓ air-Q Radon is in progress and will be available in the air-Q online shop soon


Radon (Rn) is a chemical element from the main group of noble gases and, at 9.73 mg/cm³, the heaviest of the elemental gases. It is chemically non-reactive and colourless, odourless and tasteless under normal conditions.

All isotopes of this substance are radioactive. With an average effective dose per person (in Germany) of approx. 1.1 millisievert per year (mSv/a), radon has the largest share of radiation on the earth's surface. The most stable isotope is ²²Rn, which decays to radium after a half-life of 3.8 days. This and the isotopes ²²⁰Rn (thoron) and ²¹⁹Rn (actinon) are natural isotopes in the Earth's atmosphere and can accumulate in poorly ventilated rooms.

Radon is used in medicine to stimulate the immune system. In addition, the measurement of the radon content provides information about the quality of the groundwater. Radon measurements are also used in earthquake prediction and in the search for uranium ore deposits.

Limit values for radon:

Since 31 December 2018, the reference values issued by the EU as a directive and laid down in the German Radiation Protection Act have been binding. According to this, appropriate measures must be taken to reduce Rn concentrations of 300 Bq/m³ or more - i.e. 300 decays per second per cubic metre of air - in work and recreation rooms. Due to the differing radon levels in different areas, all federal states are required to determine compliance with this reference value by 2020.

The German Radiation Protection Commission (SSK) goes into even more detail in its assessments. It defines the standard range for the Rn content in indoor air at 250 Bq/m³. Values between 250 Bq/m³ and 1000 Bq/m³ are considered a discretionary range, in which adapted ventilation behaviour is sufficient to reduce radon. In the so-called remediation range at over 1000 Bq/m³, more elaborate measures to protect against radon damage are justified. The WHO and the German Radiation Protection Commission (SSK) recommend keeping the value permanently below 100 Bq/m³.

Designationning Radon limits
EU-wide Euratom standard 300 Bq/m³ per yearthroughcut
Planningguideline value for new buildings 200 Bq/m³ per yearthroughcut
WHO recommendation 100 Bq/m³

Consequences of too high Rn concentration:

According to studies by the World Health Organisation (WHO), radiation levels between 100 and 200 Bq/m³ can significantly increase the risk of lung cancer by 10 % per 100 Bq/m³. Smokers are particularly at risk because the carcinogenic properties of radon and tobacco smoke reinforce each other. Therefore, the Federal Office for Radiation Protection recommends taking precautionary measures to reduce radon concentrations as low as 100 Bq/m³.

With regard to drinking water, the German Commission on Radiological Protection (SSK) advocates a reference value of 100 Bq/litre, above which reduction measures should be examined.

Emergence of Rn:

Radon is formed when uranium and thorium decay in rock or soil. Since it does not chemically bind to the surrounding rock, it rises to the earth's surface through tiny cracks and joints in the rock and escapes into the atmosphere, the groundwater and into caves, mines, cellars and pipelines. In areas with high uranium and thorium deposits - in Germany especially in the Ore Mountains and the Bavarian Forest - there is also an increased concentration of Rn. Especially the accumulation in cellars, which are rarely ventilated, and the subsequent penetration into the ground floor, is an imperceptible health hazard.

In mines where uranium, lead or fluorspar are extracted, as well as in factories and laboratories where radium, thorium and uranium are worked with, an increase in radon levels can also be observed.

Measurement of radon:

The air-Q Radon is in the works and is expected to be released in the first half of 2022. This will add a sensor to the air-Q to measure another important component of the air(such as carbon monoxide or carbon dioxide).

Many facts about the technology of the air-Q can be found here on the website. You can order the air analyser air-Q in the online shop.

air-Qs, which use the sensor for

Radon (Rn)


No items found.
No items found.
air-Q Air Quality Meter

Monitor air quality, all air components and environmental influences with the air-Q. For your health and performance.