Around 1,500 radon measuring devices undergoing international testing at the BfS

Preparing the radon detectors for testing

With 37 participants from 14 countries, the 20th interlaboratory comparison and proficiency testing of passive radon measuring instruments at the Federal Office for Radiation Protection (BfS) started in mid-February. For two decades, the BfS has been helping to ensure that radon measurements and the development of new measurement methods can be carried out at the highest level.

Radon measuring centres with their own evaluation laboratories and radon testing laboratories accredited according to DIN EN ISO/IEC 17025 use the comparative tests of the BfS in order to provide the proof of quality they require. In addition, manufacturers and laboratories can test new radon measurement methods or prove themselves in international competition. Apart from the BfS, there are only a few providers of such comparative tests in Europe.

Radon is a radioactive gas that is formed in the ground and which can penetrate buildings. Elevated radon concentrations in indoor air increase the long-term risk of lung cancer for people who spend time in the affected rooms. Reliable radon measurements are a basic prerequisite for identifying buildings with elevated radon concentrations and taking the appropriate measures to protect people. Around 1,500 passive measuring devices (i.e. detectors that do not require electricity) are tested.

Radon measuring devices must fulfil strict criteria

Measuring devices in the radon chamber

For the comparative tests, the BfS uses the radon chambers in its own accredited calibration laboratory in Berlin: "This allows us to precisely control the amount of radon and the duration of the measurement", explains Dr Felice Friedrich-Kees, coordinator of the tests and quality officer at the calibration laboratory. "We place around 1,500 measuring devices from the participating laboratories in the chamber and expose them to different radon concentrations and measurement durations in several runs. Only we at the Federal Office for Radiation Protection know what these are."

The laboratories then analyse the data obtained with their measuring devices themselves and report the results to the BfS. "Only if the results are within a predetermined tolerance range is the suitability of a laboratory confirmed", says Friedrich-Kees. However, the participating laboratories can also derive valuable information from outliers: "For example, it is possible to recognise whether an evaluation process needs to be readjusted or individual devices are being processed incorrectly."

Science thrives on diversity

"With the performance of radon comparison tests and the calibration services offered, the radon laboratory of the Federal Office for Radiation Protection has a prominent position internationally", says Sebastian Feige, Head of the Radon Metrology Section at the BfS. However, from a scientific point of view, he would like to see a broader diversification of expertise. "Science thrives on the diversity of ideas as well as the exchange and mutual review of theories and methods." This also applies to quality assurance and the further scientific development of radon measurement methods.

As part of the European Metrology Network, the BfS is also committed to ensuring that expertise and quality assurance services can be found and used in a coordinated metrological infrastructure.