The Effect of the Coal Industry on Indoor Radon Concentrations in eMalahleni, Mpumalanga Province of South Africa.

ABSTRACT: South Africa has rich coal deposits concentrated in the northeast of the country, and as a result, most of the country's coal mining is located in this region. Two of the principal coalfields exploited are the Witbank and Highveld coalfields, located in the Mpumalanga province. Coal contains trace quantities of the naturally occurring radionuclides whose mass concentration can be enhanced by anthropogenic activity. The radioactive fallout from these activities could lead to elevated radon concentrations indoors. Two towns, Secunda and eMalahleni, were identified due to their proximity to coal-based industries. A previous study investigated whether these industries caused elevated radon levels in Secunda homes but found a lower-than-expected average concentration of 76.4 ± 7.6 Bq m-3. This was attributed to either the prevailing wind depositing the radioactive fallout to neighboring towns, such as eMalahleni, or the type of industrial activity. This paper builds on this study by investigating whether elevated radon levels are found in homes in eMalahleni. Measurements were performed in 22 homes during December 2019, and the average indoor radon concentration was calculated as 122.1 ± 8.5 Bq m-3. The cause of these elevated levels was then investigated, and it was found that even though the coal industry contributes to elevated radon levels, the town's underlying geology seems to be the primary contributor.

The Anthropogenic Impact on Indoor Radon Concentrations for Secunda, Mpumalanga Province, South Africa.

ABSTRACT: Secunda is a town built amid the coalfields of the Mpumalanga province of South Africa. Surrounding the town are 11 coal-fired plants (CFPs) contributing around 59% of the country's energy needs. It is also home to Sasol Synfuels, which produces synthetic gas through coal gasification and natural gas reforming. Coal, like most materials found in nature, contains trace elements of the naturally occurring primordial radionuclides 40K, 238U, 232Th, and their decay products. The milling and combustion of coal in a CFP increases the mass concentration of these trace elements, and the residuals end up on ash heaps as fly ash, bottom ash, and boiler slag. A small percentage of fly ash also ends up in the atmosphere. This paper sets out to determine the anthropogenic impact of the industrial activity on indoor radon in the town of Secunda in the Mpumalanga region of South Africa. Measurements were done in 37 homes during July when higher indoor radon levels are expected due to homes typically being closed due to the low temperatures. The average indoor radon concentration was found to be 76.4 Bq m-3. This indicates that the fallout from the industrial activity surrounding Secunda does not enhance the emanation of radon. This may be due to the type of activity or the climate and prevailing winds mitigating its indoor build-up. Measurements during the warmer months and in neighboring towns with different industrial activities are required to confirm the trends established by this research.

INDOOR RADON MEASUREMENTS FOR THE SOUTH AFRICAN WEST COAST PENINSULA.

Granite commonly contains high concentrations of uranium, with consequent high exhalation of radon. The geology of the West Coast peninsula of South Africa is dominated by granite, and a recent article predicted potentially high indoor radon concentrations in this region's two largest towns, Vredenburg and Saldanha. This research aimed to measure indoor radon levels in these towns. Measurements were first done for a minimum of 3 d during warmer months, with houses typically being more ventilated. Thirty-four homes in Vredenburg and 27 in Saldanha were measured, and the average indoor radon determined to be 40 and 58 Bq m-3, respectively. The measurements were then repeated during the colder months, and an increase in average radon concentration of 173 Bq m-3 for Saldanha and 153 Bq m-3 for Vredenburg was found. The granite geology and lifestyle of occupants during the colder months seem to contribute towards elevated levels of indoor radon concentrations.