How to measure radon

and which companies do the measurements

We point out that all measurements of radon and the other natural nuclides, pursuant to Atomic Act no. 18/1997/Coll., can be made only by the companies that own the valid permission of the State Office for Nuclear Safety. For the list of the companies, see the Internet page of the State Office for Nuclear Safety

You may meet with the following requirements related to the measurements:

  • To find out the radon risk of a building site
  • To measure radon concentration and natural radionuclide concentrations in water and building materials
  • To measure radon concentration in indoor air
  • To make a detailed analysis of sources and radon propagation in a dwelling (so-called radon diagnostics).

1. Radon risk determination on a building site

The measurements are done by the commercial companies in compliance with the SUJB approved methods. The methods are based on the following procedure:

  • Drilling at least 15 exploratory wells up to a depth from 0.8 to 1 m for air sampling from the underlying soil and radon concentration measurement
  • Gas permeability determination of foundation soil
  • Determining the category of the soil radon risk on the basis of the above-mentioned measurements (i.e., low, middle, and high radon risk).

2. Radon concentration and natural radionuclide measurements in water and building material

These measurements are also done by commercial laboratories, and the list of their contact addresses you will find on Internet page For more information about the procedures of sampling, contact some of the listed companies.

3. Radon measurements in indoor air

The correct measurements and the assessment of radon concentrations in dwellings are fairly difficult - the radon concentration significantly varies in dwellings at night and during the day, and by season. Hence, it is reasonable to carry out, first of all, the measurement of the radon concentration mean value (the annual mean value or at least weekly mean values) because these measurements are not expensive. If a higher radon concentration is detected, the more complex analysis, so-called radon diagnostics, should be done.

The basic measurements are as follows:

  • The annual mean radon concentration measurement (if there is ample time, we prefer to realise this type of measurement). In such a case, track detectors are installed in the house for one year. You can purchase the detectors directly in SÚJCHBO Kamenná, or participate in the charge-free target survey that is organised by the Czech state authorities under the agreed conditions (see the National Programme of Target Survey for Houses).
  • The weekly mean radon concentration measurement (zejména pokud zjištění výsledku spěchá). (in particular, if results have to be obtained as soon as possible). The measurements are again done by commercial companies (see above). We recommend that ventilation be reduced during the radon measurement to avoid any underestimation of the annual average radon concentration (and to avoid the underestimation of exposure). The minimum number of rooms to be measured is specified: all residential rooms that are in a direct contact with the underlying soil; at least one third of residential rooms on the first floor; and at least one residential room on the other floor if there is a reasonable suspicion that a type of radioactive building material has been used.


This is a set of measurements that is used for searching for radon sources (for example, radon risk from the foundation soil is determined by this method). Radon propagation in houses, and also tightness of foundations against radon entry may be assessed by the radon diagnostics, etc. The goal of the radon diagnostics is to acquire the data for a reasonable remedial measure.