Radon gas has long been identified as a human carcinogen. The purpose of this study was to understand the occurrence of radon gas in the West Rand region, located west of the city of Johannesburg, South Africa, and to investigate its potential health effects. In this study, the sampling of rocks, tailings, and construction materials was carried out for geochemical analyses. For characterisation of radon, 60 radon monitors (RGMs) were installed in indoor and outdoor environments. The results showed that mine tailings contain high uranium levels, with a maximum of 149.76 ppm and a mean value of 48.87 ppm. The radon levels in the area ranged between 32 Bq/m³ and 1069 Bq/m³ and thus, exceed the typical outdoor radon levels of about 10 Bq/m³. Significantly high values were obtained from gold tailings dams. In indoor environments, radon concentration ranged up to a maximum of 174 Bq/m³, which is above the recommended value of 100 Bq/m³. The effective doses calculated from the obtained radon levels showed a maximum of 16 mSv/y, which is above the recommended value of 1 mSv/y proposed for public exposure. The estimated doses have an enormous potential to pose high lung cancer risks to the populations residing nearby tailings.

The mining and processing of naturally occurring radioactive materials (NORMs) could result in elevated levels of natural radionuclides in the environment. The gold mining in the goldfields of the Witwatersrand Basin of South Africa has resulted in numerous tailing dams that have high concentrations of NORM bearing residue. The aim of this study was to evaluate the radioactivity levels in tailing dams, soils and rocks, and the consequential radiological exposure to the public in the gold mining areas of Gauteng Province, South Africa. The activity concentrations of ²³⁸U, ²³²Th, and ⁴⁰K were assessed using a gamma ray spectrometer (RS-230), and the activity concentrations ranges in the mine tailings were 209.95–2578.68 Bq/kg, 19.49–108.00 Bq/kg, and 31.30–626.00 Bq/kg, respectively. The radionuclides show significant spatial variability in soils, with high activities recorded in soils located in close proximity to tailings although regionally, the soil radioactivity levels mainly depend on the chemistry of the underlying rocks. The estimated annual effective doses were higher than the recommended regulatory limit of 0.25 mSv/y in particular tailing dams and soil impacted by tailings. Therefore, to ensure the protection of people and the environment, further monitoring and regulatory control measures targeting these areas are required.

Radon in dwellings is recognized as the primary source of natural radiation exposure to members of the public. In the West Rand District and Soweto in the Gauteng Province (South Africa), indoor radon (²²²Rn) mapping was carried out to assess the exposure levels of radon in dwellings around gold and uranium mining tailings dams. This study was conducted predominately during warm and cold seasons, using the solid-state nuclear track detectors. In summer months, the indoor radon levels measured in all areas ranged from below the lower limit of detection to 71 Bq/m³, with a mean value of 29 Bq/m³, whereas in winter, the levels ranged between 11 and 124 Bq/m³, with a mean value of 46 Bq/m³. Higher indoor radon levels are found in colder months (winter season) than warmer months (summer season). However, no dwellings with indoor radon levels that exceed the WHO (2009) recommended reference level of 100 Bq/m³ were found, except for one that was constructed directly on soil mixed with tailings material. It is recommended that residents should keep their indoor radon levels low through continuous ventilation so as to minimize the buildup of radon and the likelihood of increased health hazards associated with radon exposure.

Coal mining and combustion have the potential to increase exposure to radon, a form of radioactive gas recognized as one of the major contributors to lung cancer incidents. In South Africa, coal is used as the primary energy source for producing electricity and for heating, predominantly in informal settlements and township communities. Most of the existing coal-fired power plants are found in the Mpumalanga province. This paper presents long-term radon (²²²Rn) measurements in dwellings surrounding coal mining centres in the Mpumalanga province and evaluates their contributions to indoor radon exposures. The indoor radon measurements were conducted using solid-state nuclear track detectors and were performed during warm and cold seasons. It was found that the overall indoor radon activity concentrations ranged between 21 Bq/m³ and 145 Bq/m³, with a mean value of 40 Bq/m³. In all the measured dwellings, the levels were below the WHO reference level of 100 Bq/m³ and 300 Bq/m³ reference level recommended by the IAEA and ICRP, with the exception of one dwelling that was poorly ventilated. The results reveal that individuals residing in the surveyed homes are not exposed to radon levels higher than the WHO, ICRP, and IAEA reference levels. The main source influencing indoor radon activity concentrations was found to be primarily the concentration of uranium found in the geological formations in the area, with ventilation being an additional contributing factor of radon levels in dwellings. To maintain good air quality in homes, it is recommended that household occupants should keep their dwellings well ventilated to keep indoor radon levels as low as possible.

Naturally occurring radionuclides arises mainly from natural sources and anthropogenic activities such as mining. In South Africa, gold mining in the goldfields of the Witwatersrand Basin has resulted in numerous tailing dams that have high concentrations of NORM bearing residue. The aim of this study was to evaluate the surface radioactivity levels in and around the gold tailing dams of Gauteng Province in South Africa and further determine the consequential radiological exposure to the public. The portable BGO SUPER-SPEC (RS-230) spectrometer, with a 6.3 cubic inches Bismuth Germanate Oxide (BGO) detector was used to measure the activity concentrations for 238U, 232Th and 40K in mine tailings, soils and underlying rocks. This work was conducted on a regional scale and covered the West Rand, East Rand and Central Rand Districts of the Gauteng Province, which are dominated by the abandoned gold tailings dams. Of the three radionuclides that were studied, 238U was found to be the most significant radioactive contaminant of radiological concern. High 238U concentrations (209.95 to 2578.68 Bq/kg) were found in the mine tailings than in the surrounding soils (9.88 to 941.07 Bq/kg) and rocks (11.12 to 71.63 Bq/kg). In surface soil, the radionuclides show significant spatial variability with high activities recorded in soils located in close proximity to tailings thus signifying the adverse environmental impacts of mining in the study area. The annual effective dose estimations indicate that the mine tailings found in the area and soils impacted by tailings significantly contribute to the external gamma radiation received by members of the public. This therefore highlight the need for further monitoring and regulatory control measures targeting these affected areas, in order to ensure the protection of persons and the environment within the areas.Keywords: activity concentration; gold mine tailings; in situ gamma ray spectrometry; radiologicalexposures; South Africa

Human activities such as mining and processing of naturally occurring radioactive materials have a potential to result in enhanced radioactivity levels in the environment. In South Africa, there has been extensive mining of gold and uranium which produced large mine tailings dams that are highly concentrated with radioactive elements. The purpose of this study was to carry out a preliminary survey on a large scale to assess the activity concentrations of 238U, 232Th and 40K in mine tailings, soils and outcropping rocks in the West Rand District in South Africa. This was done to better understand the impact of the abandoned mine tailings on the surrounding soil. This study employed in-situ gamma spectrometry technique to measure the activity concentrations of 238U, 232Th and 40K. The portable BGO SUPER-SPEC (RS-230) spectrometer, with a 6.3 cubic inches Bismuth Germanate Oxide (BGO) detector was used for in-situ measurements. In mine tailings the activity concentrations for 238U, 232Th and 40K were found to range from 209.95 to 2578.68 Bq/kg, 19.49 to 108.00 Bq/kg and 31.30 to 626.00 Bq/kg, respectively. In surface soil, the activity concentration of 238U for all measurements ranged between 12.35 and 941.07 Bq/kg, with an average value of 59.15 Bq/kg. 232Th levels ranged between 12.59 and 78.36 Bq/kg, with an average of 34.91 Bq/kg. For 40K the average activity concentration was found to be 245.64 Bq/kg, in a range of 31.30 - 1345.90 Bq/kg. For the rock samples analyzed, average activity concentrations were 32.97 Bq/kg, 32.26 Bq/kg and 351.52 Bg/kg for 238U, 232Th and 40K, respectively. The results indicate that higher radioactivity levels are found in mine tailings than in rocks and soils. 238U was found to contribute significantly to the overall activity concentration in tailings dams as compared to 232Th and 40K. It has been observed that the mine tailings have a potential to impact on the activity concentration of 238U in soil in the immediate vicinity. However, on a regional scale it was found that the radioactivity levels in surface soil mainly depend on the radioelement concentration of the underlying rocks. The contamination is only confined to areas where mine tailings materials are washed off and deposited on surface soils in close proximity to tailings sources. This serves as an indication that the migration of uranium from tailings dams is localized and occurs within short distances. It is recommended that further radiological monitoring be conducted in areas found to have elevated concentration of uranium-238.Keywords-In-situ gamma-ray spectrometry, Mine tailings, Radioactivity, Soil.