Traces of 137Cs detected in the air over Europe following wildfires in the Chernobyl exclusion zone in September 2024
In the past, there have been various wildfires in the area around Chernobyl. For example, in April 2020, several large forest fires broke out in Ukraine, reaching the surroundings of the former Chernobyl nuclear power plant (see article by Masson et al., 2021, linked below). This region has been heavily contaminated with cesium-137 due to the accident in 1986. The fires cause this radioactive cesium isotope to be released into the atmosphere.
Following a period of drought conditions in northern Ukraine, fires recently broke out again in the Chernobyl exclusion zone. At the end of August, wildfires were detected approximately 50 to 65 km west of the plant. On September 3, several of these fires were visible from monitoring satellites. Due to an anticyclonic weather pattern, the smoke plumes first moved westward toward Ukraine, then into Poland, Scandinavia, and much of northern Europe. As of September 12, rainfall in northern Ukraine significantly reduced the intensity of the fires.
In Switzerland, during the collection period from September 16 to 23, samples from all six high-volume aerosol collectors (at CERN-Geneva, Güttingen, Cadenazzo, Liebefeld, Klingnau, and Posieux) contained low levels of this radionuclide, with values ranging from 0.2 to 0.9 microBq/m³. The typical maximum concentrations of cesium-137 measured in Switzerland range between 1 and 2 microBq/m³, depending on the station, but concentrations are often below detection limits in HVS stations located north of the Alps, except in winter. Although the measured concentrations in September 2024 are low, the fact that this radionuclide was detected simultaneously in all Swiss stations suggests an additional input, likely from the fires in the Chernobyl region.
The high-volume aerosol collector (HVS) network, managed by the Federal Office of Public Health (FOPH), allows the detection of very low traces of radioactivity in the air in Switzerland. Currently, six stations are in operation. After a seven-day exposure period, which corresponds to the routine work schedule, the aerosol filters are sent to the laboratory for analysis. The results are then published on the platform www.radenviro.ch.
Additional information on this topic:
- The Institute for Radiological Protection and Nuclear Safety (IRSN) published a very detailed article on September 27, 2024, on the monitoring of this contamination in Europe (link).
- The following scientific article was published on the 2020 Chernobyl forest fires and the resulting spread of cesium-137 in Europe:
Masson et al., 2021. Europe-Wide Atmospheric Radionuclide Dispersion by Unprecedented Wildfires in the Chernobyl Exclusion Zone, April 2020. Environ Sci Technol, 13834-13848
