Blåbetong

One of the most common indoor radon sources

Blåbetong (blue concrete) is a lightweight aerated concrete made from alum shale that was manufactured at various sites across Sweden between 1929 and 1975. The material contains raised levels of radium, and as the radium decays it forms radon that slowly seeps out into the rooms. That is why blåbetong is counted among the most common radon sources in homes.

The reference level is 200 Bq/m3

A home containing blåbetong does not automatically mean the radon level is too high. How much radon actually ends up in the air depends on the type of concrete and on the ventilation. The reference level for radon in indoor air in homes is 200 Bq/m3, and the only way to know where your home sits is to measure.

What you should do

If the home was built or renovated between 1929 and 1975, ask the broker (mäklare) whether a radon measurement has been done. If there is none, you can carry one out yourself after moving in. A long-term measurement during the heating season gives the most reliable value. If the level comes out above the reference level, it can usually be brought down, most often by improving the ventilation. So blåbetong is nothing to panic about, but it is worth measuring before you draw any conclusions.