Measurement of radon concentration in metro stations of Istanbul, Türkiye

The main objective of this study was to determine the levels of radon concentrations in different metro lines in Istanbul. Measurements were conducted in underground stations of five distinct metro lines: M1A, M1B, M3, M4 and M6. Radon activity concentration (RAC) values were determined by means of measurements. The annual effective dose values were calculated for employees on the metro line and for passengers using these lines. The lowest radon concentration was found to be 15 Bq/m3, while the highest was 80 Bq/m3. It has been shown that the effective dose received by individuals from radon irradiation in underground stations does not appear to contribute significantly to the annual average effective dose. The city of Istanbul is characterised by a rugged topography, with some metro stations reaching depths of up to 40 m below ground level. Despite this, the increasing depth of the metro stations did not result in a significant increase in radon concentration.