Radon in dead-end caves in Europe

Miloš Briestenský, Fabrizio Ambrosino, Iveta Smetanová, Lenka Thinová, Stanka Šebela, Josef Stemberk, Lucia Pristašová, Concepción Pla, and David Benavente

ABSTRACT:

We report the results of 3-years of Radon-222 monitoring in six show caves across Europe, selected with the feature of having only one, or no natural entrance, defined as dead-end caves. The caves are located in Spain, Slovakia, Slovenia, and Czechia. The consecutive monitoring was performed between January 2017 and January 2020. Continuous measurements of the radon activity concentration using spectrometry detection and analysis of the ?-particles of 222Rn progeny were performed. Meteorological parameters influencing gas flow were recorded inside and outside of the caves. Although the radon activity concentrations differed from one cave to another, all six of the studied caves revealed very similar trends, showing evident seasonal variability with higher values in summer and lower values in winter. The measured values of radon activity concentrations ranged between 633 and 26,785 Bq/m3. The temperature differences between the inside and outside of the caves is the main radon movements driving force. The results of this study have significant practical implications, making it possible to provide cave administrators with recommendations regarding employee or visitor time-limited access to the investigated caves. Ours is the first comparative study encompassing the most interesting dead-end caves in Europe

SIMPLE LANGUAGE SUMMARY:

This report talks about a three-year study where scientists monitored levels of a gas called Radon-222 in six tourist caves in Europe. These caves, located in Spain, Slovakia, Slovenia, and Czechia, were selected because they have only one entrance or no natural entrance, and are called dead-end caves. The study took place from January 2017 to January 2020. The scientists used special equipment to measure the amount of Radon-222 in the caves. They also recorded weather conditions both inside and outside the caves, because these can affect how the gas moves around. The amount of Radon-222 varied from cave to cave, but all six caves showed the same patterns over time. They found more of the gas in the summer and less in the winter. The Radon-222 levels ranged between 633 and 26,785 Bq/m3 (a unit of measurement for radioactivity). The main factor driving the movement of the gas was the difference in temperature between the inside and outside of the caves. The findings of this study are really important in a practical sense, as they can help the people who manage these caves. They can use this information to limit the time that employees or visitors spend in the caves to reduce their exposure to the gas. This is the first study that compares Radon-222 levels in these specific types of caves across Europe.