This website uses cookies to improve your browsing experience and the continued use of the webpage indicates your consent to ÅF’s use of these cookies. Find out more about how ÅF uses cookies and how you can manage them here: Read more


We know radon

Let ÅF help you measure and reduce radon levels.

Radon is a gas produced by the natural decay of certain radioactive heavy metals. The radon atoms often become attached to particles of dust that can then be inhaled. The National Board of Health and Welfare in Sweden has recently reduced the threshold value for radon. In schools and preschools in Sweden a threshold value of 200 Bq/m3 must be met by 2010. This value must be met in homes by 2020. Radon is odourless, tasteless and invisible, so the only way to detect it is by measuring it.

Three sources of radon in indoor air

The presence of radon in air indoors can be traced to three sources: the substrate (i.e the ground), the building materials used, and/or the water.


Radon is present in the ground throughout Sweden, with the exception of the Baltic Sea island of Gotland, which lies on a bedrock of chalk. Air from the ground seeping up through minute cracks in the foundation of a building may transport radon into the indoor air. Even a small amount of seepage can increase the radon concentration indoors.

Building materials

Until around 1975 blue porous concrete was used widely in Sweden and elsewhere in both walls and ceilings/floors. The number of walls and ceiling/floor slabs in a building that are made of this type of lightweight concrete is one of the factors that affect ambient radon levels indoors. Poor ventilation in buildings constructed using blue porous concrete can increase the concentration of radon indoors.


Usually the risk of radon in drinking water supplied by municipal waterworks is minimal. However, excessive levels of radon can occur in private wells drilled in rock.

Measuring radon and taking appropriate action

ÅF consultants measure radon concentrations in indoor air and carry out checks to determine whether blue porous concrete has been used in the construction of the premises. On the basis of these measurements, appropriate action can then be proposed when necessary.