# Which state has the highest radon levels

• Because soil air containing radon penetrates buildings from the building site, radon occurs in all indoor spaces.
• Which radon concentrations actually occur in the common rooms of a house can only be clarified by measurements.
• The BfS had a map drawn up showing the average concentration of radon in apartments in Germany. Statements on individual buildings cannot be derived from the map.

Radon penetrates into buildings from the subsoil and accumulates there. A small part of it also gets into buildings from building materials and from drinking and service water. Radon can cause lung cancer there.

The gas can spread to all rooms. As a rule, the concentration is highest in the basement and on the ground floor. The radon concentration usually decreases on higher floors because the radon penetrating from the building underground mixes more and more with the low-radon outside air on the higher floors.

### Measured values ​​and forecasts

The level of radon concentrations in buildings varies widely. The average annual value in common rooms in Germany is 50 Becquerel per cubic meter, but more than 1,000 Becquerel per cubic meter is possible, but rarely occurs.

The radon concentrations in the interior of an individual building cannot be predicted. They can only be determined through measurements.

### Map "Radon Concentrations in Apartments"

Average radon concentrations (geometric mean) in apartments in Germany Source: according to Menzler et. al.

The map shows the geometric mean of the average concentration of radon in common rooms for the rural districts and urban districts in Germany (as of 2005). The map clearly shows the extent to which the radon concentrations in common rooms in Germany can vary regionally.

The different radon concentrations depend not only on the radon concentration in the subsoil of the building, but also on the building fabric in the investigated districts and urban districts: The "lighter spots" of some urban districts are in the "darker surroundings" of rural districts With a high geometric mean, this can be explained by the fact that the proportion of apartment buildings with a higher number of floors is greater in cities. In common rooms on higher floors, the radon concentration is usually significantly lower than in common rooms at ground level. As a result, the number of common rooms with relatively low radon concentrations in cities can be higher than in rural areas.

### Estimation based on representative measurement data

The map was created in 2006 as part of the study "Assessment of the attributable lung cancer risk in Germany due to radon in apartments" and is based on a statistical analysis of around 60,000 measurements in around 27,000 apartments, which were carried out on behalf of the federal government from the beginning of the 1980s to 2005 were made.

The study estimated the proportion of all lung cancer cases caused by radon in homes.

### The radon situation on site can only be clarified through measurements

Statements on the radon concentration in individual buildings or in the building site of certain properties cannot be derived from the map.

The radon situation in an existing building can only be determined by measuring the radon concentration in the room air.