Quality assurance of radon measurements

Quality assurance requirements for measuring devices and laboratories concerned with the evaluation of measuring devices are laid down in the Richtlinie Arbeiten (Guideline on work activities) and in the Leitfaden "Überwachung von Strahlenexpositionen bei Arbeiten" (Guide to the monitoring of radiation exposure during work activities”). These requirements were in the first instance aimed at measurements performed under Part 3 Chapter 2 of the Radiation Protection Ordinance for the purpose of monitoring occupationally exposed persons. Beyond that, however, the Federal Office for Radiation Protection (Bundesamt für Strahlenschutz, BfS), recommends to apply these criteria to radon measurements in homes as well.

The following should be kept in mind when radon measurements are carried out or arranged for:

Measurements using passive measuring devices

Use of passive measuring devices involves exposure of measuring probes obtained from a laboratory. After exposure, the probes are returned to the laboratory. This latter will determine the level of radiation exposure and communicate it to the person who had arranged for the measurements.

Laboratories for radon measurements based on passive measuring devices have to prove their organisational and professional competence to accomplish their measuring tasks. This can be done either by accreditation through an accreditation body or by approval through the Federal Office for Radiation Protection.

In addition, it is mandatory for the types of measuring devices provided by the laboratories to participate in the annual comparison tests conducted by the Federal Office for Radiation Protection. The table below shows the laboratories offering radon measurements based on passive measuring devices in Germany that have proven to meet the quality assurance requirements.

Measurements based on electronic measuring devices (direct reading measuring devices)

With electronic or direct reading measuring devices, the measured value is either displayed on the device, or determined by means of a computer or another electronic device immediately after the measurement. The minimum requirement of quality assurance is to ensure that a valid calibration is available for the measuring device.

A calibration is regarded as valid when it has been performed by an approved calibration laboratory and is not older than two years. The validity of the calibration can be determined by reference to the calibration certificate or the calibration label.

The calibration certificate, issued by the calibration laboratory, includes all relevant data on the measuring device and the calibration tests performed. After calibration, the calibration label is attached to the outside of the measuring device.