The highly mineralised formation waters in the coal mines of Poland’s Upper Silesian Coal Basin contain natural radioactive nuclides, mostly radium. The ²²⁶Ra concentration in the groundwater that flows into the underground mine workings reaches 390 Bq/L, and is sometimes exceeded by the ²²⁸Ra concentration. The radium-bearing water sometimes also contain barium ions, which enables coprecipitation of barium-radium sulphate. Another type of radium-bearing water contains sulphate ions instead of barium; in this case, radium is transported to settling ponds and downstream. We have assessed the daily activity of radium in waters flowing into the underground mines and being discharged to the environment. Based on 1995 data, we estimate that the total activity of radium isotopes flowing into the mines was about 1300 MBq/day, while the radium activity in the discharge waters was about 700 MBq/day. A similar assessment performed with 2016 data indicated that the total activity in inflows was roughly 1150 MBq/day, while that discharged to surface waters was about 450 MBq/day.

The objective of this work was to perform a series of measurements of radon and thoron exhalation in the underground workings of an experimental coal mine. In the years 2012–2015, experiments on underground coal gasification were carried out in a coal mine, which caused, among other effects, damage to rock mass. Afterward, periodic increases in the concentration of potential alpha energy (PAEC) of radon decay products in the air were found, which could pose a hazard to miners. The question posed was whether the gasification experiment resulted in the increased migration of radon and thoron. If so, did it increase the radiation hazard to miners? The adaptation of the existing instrumentation to the specific conditions was conducted, and a series of measurements were made. It was found that the measured values of radon and thoron exhalation rates ranged from 3.0 up to 38 Bq·m⁻²·h⁻¹ for radon and from 500 up to 2000 Bq·m⁻²·h⁻¹ for thoron.

The article presents the results of radon research, carried out in the area of the mining commune in the Upper Silesian Coal Basin (USCB), Poland. Past investigations in the 1990s on radon concentrations in buildings, located within the mining area, showed that the indoor radon concentrations measured in the area affected by mining were higher than in buildings located outside that area. Currently, all underground hard coal mines within the boundaries of the observed commune have been closed. In 2020, after the closure of the last active mine, radon measurements were started again. The current results of indoor radon concentrations were compared with the archival results from the 1990s. It was found that the radon concentration increased significantly in the basements of buildings where measurements were made in 1990, 2020, and 2021: the maximum values were 260 Bq/m³, 644 Bq/m³, and 1041 Bq/m³, respectively. Therefore, these questions were posed: Do the mine closure processes increase radon migration? How long is the period of the occurrence of changes in radon concentrations in buildings after the cessation of mining operations?

The new basic safety standards (BSS) Directive 2013/59/Euratom [1] puts EU member states under an obligation to establish, amongst others, national radon action plans. In order to address the issue of long-term risks from radon exposures, it is important to identify areas where elevated levels of radon can be expected. One of the types of areas affected by an increased migration of radon and by the penetration of radon into buildings are areas in which industrial activity, for example, the exploitation of mineral resources, causes changes in the geological environment. The Upper Silesian Coal Basin (USCB) in Poland is one of the examples. The results of studies conducted in the past have shown that the levels of indoor concentration of radon, to a large extent, depend on the geological structure of the subsurface layers. One of the main factors influencing the migratory abilities of radon are the mining-induced changes of a rock body. We estimate that in specific radon-prone zones, the levels of radon may exceed 300 Bq/m³ in approximately 2% of the dwellings. Another problem that may appear in post-mining areas is linked to the reclamation of radioactively contaminated areas. The complex geology of the strata in USCB, the mining activity that can be observed in the region and, additionally, the discharge of radium-bearing waters into the environment are the most significant factors affecting radon potential and hazard in dwellings in this region. In this paper, problems linked to the detection of radon in the mining area of USCB are presented.