The natural γ-radiation in samples of a variety of marbles
imported into Bangladesh for use in building construction was measured,
employing γ-ray spectrometry with a HPGe detector. From the measured
γ-ray spectra, activity concentrations were determined for 226Ra
(29.31 ± 2.06 to 46.99 ± 2.97 Bq.kg–1), 232Th (42.91
± 2.53 to 62.92 ± 3.37 Bq.kg–1) and 40K (824.42
± 15.42 to 1071.58 ± 20.14 Bq.kg–1). The measured activity
concentrations for these natural radionuclides were compared with
the reported data of other countries and with the world average
activity of soil. The radium equivalent activity (Raeq),
the hazard indices, the gamma activity concentration index, the
indoor absorbed dose rate and the corresponding annual effective
dose were estimated for the potential radiological hazard of the
marble. The Raeq values of all marble samples are lower
than the limit of 370 Bq.kg–1, equivalent to a dose of
1.5 mSv.y–1. The average values of the external and internal
hazard indices are less than unity. The average indoor absorbed
dose rate (121.25 nGy.h–1) is higher than the population-weighted
average of 84 nGy.h–1, whereas the corresponding annual
dose limit falls within an average value of 0.60 mSv, which is an
order of magnitude below the limit specified for building materials
in the literature. The present results indicate that using marble
in building construction in Bangladesh does not pose any significant radiological
hazard.