The NEOC runs its own radioactivity monitoring network – NADAM. It consists of 71 stations located at the MeteoSwiss weather stations throughout Switzerland, which transmit the measured values at ten-minute intervals back to the NEOC. If the threshold value (1000 nanosievert per hour [nSv/h]) is exceeded, an alarm is automatically raised.
Here you can consult the average daily values for each of the 71 monitoring stations. Depending on the location, the average values vary between 80 and 260 nanosievert per hour (nSv/h). This is mainly due to differences in the level of natural radiation. Key factors are, on the one hand, the geological composition of the ground, and on the other hand, the intensity of cosmic radiation. These values increase the higher you are above sea-level. Therefore the stations in the Alps (e.g. Jungfraujoch) are measuring much higher values. The highest natural radioactivity values in Switzerland are measured at the Piz Giuv, north of Sedrun. The maximum values are approximately 500 nSv/h.
At all NADAM stations, the proportion of artificial radiation amounts to only a few percent. The artificial part mainly comes from 1986 Chernobyl reactor accident and from nuclear weapons tests in the 1960s.
The onset of rain can lead to a temporary increase in the measured values as a result of the natural radioactivity being rinsed from the air. The intensity of the rainfall, and the duration of the previous dry period are decisive here.
In the winter months, the snow cover can reduce the proportion of ground radiation to such an extent that the measured values are below those observed in the long term.
The records for the previous three days are also available. The records are updated twice daily at 8 a.m. and 3 p.m.