Information for construction professionals

If radon protection is already taken into account during the planning and construction of new buildings and additions or during renovations in which horizontal components in contact with the ground are newly erected down to the ground (foundation level), this can usually be implemented easily and cost-effectively. Further information on structural radon protection as well as everything about radon itself can be found in this section.

What is radon?

The naturally occurring noble gas radon is formed by radioactive decay from uranium and is itself radioactive. Radon can accumulate in buildings under unfavorable conditions, where it is constantly inhaled. It is not perceptible to the human senses. Nevertheless, it can be easily measured.

Since radon is formed during the radioactive decay of uranium and uranium is present in almost all soils, radon is also formed everywhere. As a gas, it can pass with the soil air through cracks and crevices in the foundation and thus into the indoor air. Under unfavorable circumstances, very high radon concentrations can thus occur in buildings. To protect the health of those people who stay in these buildings, such a situation should be avoided by precaution or remediation.

Since radon only becomes a problem when it accumulates in indoor air in buildings, it is a technologically related indoor pollutant. Outdoors, there is generally a strong dilution, so that no radon concentrations of concern occur.

Radon in buildings

Factors influencing radon concentration indoors

The radon concentration in buildings depends on the air exchange rate in the building, the condition of the building and the nature of the subsoil. The chimney effect can lead to an accumulation of radon in the indoor air.

Air exchange in the building

The exchange between indoor air and outdoor air has a significant influence on the level of indoor radon concentration. Leaky windows and doors lead to higher air exchange rates. If the air exchange rate is reduced by installing tightly closing windows and doors, the indoor air concentration of radon can increase considerably.

Building condition

The tighter the building envelope is designed against the ground, the better the protection against radon. The permeability of a building to the soil air is decisive. This applies to the foundation area as well as to masonry in contact with the ground. Possibilities of penetration exist through cracks and crevices as well as along cable and pipe penetrations. If cellars or other areas of buildings in contact with the ground are open to the living area, radon can spread particularly easily into the living area.

Inhabited buildings act like suction bells, especially during the cold season. The reason for this is a low negative pressure that sucks radon-containing soil air into the building. The effect is called "chimney effect" and is caused by temperature differences between indoor and outdoor air or also by wind pressure.

Condition of the substrate

The composition of soil and rock (uranium and radium content) and the grain size of the rock play an important role. The grain size provides information on how much radon is released to the soil air. The permeability of the subsurface determines whether onward transport of radon-containing soil gas occurs.

Special caution against elevated indoor radon concentrations is required for rubble cones and slopes, weathered granite, karst and gravel soils. This contrasts with very compact soils, for example, clayey soils.

Effective measures - simply set

An elevated radon concentration can often be reduced by simple structural measures or changes in user behavior. Even simpler and more effective is the installation of precautionary measures in new buildings or also as part of general renovations.

Radon Network Austria

The Radon Network has been in existence in Austria since September 2021. The aim of the network is to connect interested parties from various industries and to offer them the opportunity for exchange. For more information on the Radon Network Austria, please refer to the chapter Radon Network Austria.