The influence of different types of granite on indoor radon concentrations of dwellings in the South African West Coast Peninsula

Granite commonly contains high concentrations of uranium, with subsequent high exhalation of radon gas. The geology of the West Coast Peninsula of South Africa is dominated by granite. No measurements of radon gas has, however, been undertaken in, or near the towns of the peninsula and a recent article predicted potentially high indoor radon concentrations in the town of Saldanha. This article sets out to validate the predicted results by measuring the indoor radon concentration for the two largest settlements on the West Coast Peninsula: Vredenburg and Saldanha. Measurements were conducted during the summer months with houses typically being more open due to the warm weather. The data was found to exhibit lognormal behavior, with the I-type granite formation of Vredenburg yielding a higher indoor radon concentration than the ignimbrite formation of Saldanha. The average indoor radon concentration of Vredenburg was 34% higher than that of Saldanha, with 58.7 Bq/m³ and 38.6 Bq/m³ respectively