Radon measurement results: what comes next?

Start with the results you have

Send the complete report if you have it. A device reading or photograph of its display can also start the discussion; together, we will identify any additional information needed.

• Dates, duration and type of measurement: passive detector or electronic monitor.
• Recorded concentrations, rooms concerned and floor level.
• Room use, ventilation and any work already carried out.

Read the result in context

Radon concentration is expressed in Bq/m³. To interpret a value, we consider the duration, period and measurement conditions, as well as room occupancy. A peak and a long-term average have different meanings.

The Swiss reference level of 300 Bq/m³ concerns the annual average concentration in regularly occupied rooms. A recognised measurement documents this assessment; electronic monitoring graphs provide information about fluctuations and how the building operates.

Understand the building before choosing the work

When results indicate a problem, the survey involves approximately one week of simultaneous measurements in all rooms and other spaces in contact with the ground. Measurement points on upper floors extend the analysis where necessary.

Comparing the readings over time helps identify likely entry points and understand how radon moves through the building. These findings form the basis of a mitigation proposal; further tests may be needed.

Next steps guided by the findings

• A clearly identified problem: preparation of a mitigation proposal, taking existing measurements and any necessary confirmation into account.
• Low concentrations or intermediate results: passive detectors proposed to extend or confirm the assessment over a longer period.
• After mitigation: monitoring before and after the work, a mitigation report and confirmation using passive detectors.

You can send documents after the first contact. A letter from the authorities is also useful if it specifies a procedure or deadline.