Measures for the Protection From Elevated Radon Concentrations in Buildings

Radon protection by suitable building measures

Radon protection by baseplate sealing and low pressure in the foundation using radon drainage (Click to zoom.)

People considering the refurbishment of a building should evaluate the possible health risk beforehand. The basis for this is the annual mean value of the radon concentration in rooms that are used frequently (such as the living room, the sleeping room, or the nursery). Measurements which are performed only once have no informational value here.  Depending on how often and how long people air their rooms, the concentration of the gas changes. Since people air their rooms more frequently in the warmer seasons and, thus, there is a higher exchange of gas, the radon concentrations are lower at these times.

National and international research has shown that there is an increased risk of approximately 10 per cent per 100 Bq/m3 compartment air, of contracting lung cancer.. Those who stay over years in rooms where concentrations around 1000 Bq/m3 are measured, have a risk of contracting lung cancer that is twice as high, compared to the risk of persons staying in rooms with an annual mean value around 100 Bq/m3. Therefore, it is advisable to refurbish buildings with a radon exposure which exceeds 100 Bq/m3.

Where and when are refurbishment measures reasonable?

Radon is a gas generating/which forms in the soil. Therefore, potential spots where the radon can get into the building are mostly to be found in areas of the building that have contact to the soil, such as house walls, foundation, or cellar. Through cracks, gaps, or pipe penetrations, the gas finds its way to the interior of the building. However, radon also gets into the house from the external air, and even some construction materials release the gas.
At a radon concentration of more than 100 Bq/m3, the radon from the underground prevails. In cases like this, refurbishment measures are reasonable. Often, simple measures are already sufficient, such as
  • Frequent, intensive airing
  • Sealing of cracks, gaps, and pipe penetrations areas of the house touching the soil
  • Sealing of cellar doors
As radiation exposure does not only depend on the radon concentration in the ambient air but also on the length of time persons stay in rooms, it may be another point to change the usage of the room.

How rapidly refurbishment work should be carried out depends on the annual mean value. The recommended period up to refurbishment depends on the level of radon concentration.  At compartment air concentrations higher than 1,000 Bq/m3, measures should be completed within three years. Before a building is refurbished, an expert should first determine the causes of the elevated values and evaluate the constructional situation.  Taking into account the effort and prospects of success, different refurbishment options should be weighed against each other. In general, it should be said that the higher the radon concentration is, the more efficient a refurbishment measure should be,  People planning renovation and extension work should pay attention to them during refurbishment work and, if possible, take them into account. After refurbishment has been completed, it is recommended to evaluate the success of the measures through measurements. Here you will find a list of testing laboratories providing passive measuring devices and quality assured evaluations.

What should be considered when building a new house?

New buildings should be planned in such a way that average radon concentrations in living space exceeding 100 Bq/m3 per year are avoided. In most cases, the construction measures that are used according to today’s state-of-the-art of technology, are sufficient, that is, mainly the insulation of walls touching the soil and of the foundation from soil humidity. Radon-tight construction materials and thorough construction work provide additional protection. For areas with elevated radon concentration or very permeable building ground, special techniques have been developed and tested. In such cases, the radon concentration in the soil air should be measured first. Subsequently, appropriate measures can be selected to seal the construction against radon.

German handbook on Radon

For the German Handbook on Radon, the Federal Office for Radiation Protection (BfS) has compiled detailed informations regarding the design of radon mitigation measures. If you are interested in purchasing a copy (in German), please send an e-mail to info@bfs.de.
The Federal Office for Radiation Protection | Contact us | State of 2011/12/21