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Radon and asbestos represent two health hazards that are associated with geology.

Radon enters buildings from the soil.
Radon enters buildings from the soil, possibly leading to indoor air pollution.



Radon arises from the decay of uranium in the soil zone and is present there in variable concentrations. The more permeable the soil is, the easier the gas rises to the Earth’s surface. Because a slight negative pressure often prevails in occupied houses, it is practically sucked in and accumulates in rooms – especially if the building is not sufficiently sealed off from the ground.

The risk of lung cancer increases when radon is regularly inhaled in elevated concentrations. In Switzerland, radon is the second most common cause of lung cancer and results in 200 – 300 deaths annually. The geological and climatological conditions in Switzerland aggravate the problem: uraniferous granite regions and karst soils, long heating periods with little ventilation.

The radon concentration – measured in Becquerel per cubic meter [Bq/m3] – is easily and economically recorded using small dosimeters. As of 1.1.2018, the limit value of 1000 becquerels per cubic meter (Bq/m3) is replaced by a reference level of 300 Bq/m3 for the average annual concentration of radon gas in "premises where people stay regularly for several hours a day". In addition to this reference level, a threshold value of 1000 Bq/m3 is applicable for the average annual concentration of radon gas at workplaces exposed to radon.


Asbestos refers to a group of mineral fibers found in certain rocks. There are two main groups: serpentine asbestos and amphibole asbestos.

When these fibers remain in the lung tissue for years, they can cause various diseases, some of which are cancerous in nature. It is therefore important to keep the exposure of the population to asbestos fibers in the air as low as possible.


The radon map indicates the probability [%] of exceeding the reference value of the radon concentration of 300 Bq/m3 in a building.

Cantonal geoportals more accurately portray the radon risk.

Predictive modeling of radon concentrations is being researched at the institute of radiophysics (CHUV) in Lausanne. Measurements from buildings as well as natural environment factors (e.g., sediment thickness, tectonics or lithology) are used as input.

Geology in everyday life

Radon map