Estimation of radionuclides content and radon–thoron exhalation from commonly used building materials in India

Measurement of radium (²²⁶Ra) and thorium (²³²Th) content, and exhalation rate of radon (²²²Rn) and thoron (²²⁰Rn) from soil and building materials are important in the context of modeling indoor radon and thoron concentration. In this study, exhalation rates of radon and thoron from commonly used building materials in India were measured using active measurement techniques. Also the activity concentrations of ²²⁶Ra, ²³²Th and potassium (⁴⁰K) in building materials were measured by HPGe gamma spectrometric technique. The activity concentration of ²²⁶Ra, ²³²Th and ⁴⁰K varied from 16.4 ± 4.4 to 114.7 ± 3.4, 13.3 ± 1.5 to 153.9 ± 16.6 and below detection limit to 1,007 ± 40 Bq/kg with arithmetic mean 40.3, 61.9 and 822 Bq/kg, respectively, for the examined building material samples. The radon exhalation rates from the building materials varied from 0.5 ± 0.01 to 62.9 ± 12.5 mBq/kg/h for powder samples, 73 ± 5 to 6,000 ± 310 mBq/m²/h for structural building materials while the thoron exhalation rates varied from 0.07 ± 0.27 to 15.03 ± 2.1 mBq/kg/h for samples in powder form. Radium equivalent activity calculated for coarse aggregate and brick powder samples ranged between 73 and 343 Bq/kg.