Samples of natural and manufactured building materials used by the people of Gobichettipalayam town have been analyzed for
226Ra, 232Th and 40K using gamma-ray spectrometry. Radium equivalent activity of the materials has been measured using the formula given by OECD
and the geometric mean value of sand, clay and cements are found to be 53.53 Bq·kg−1, 89.09 Bq·kg−1 and 72.25 Bq·kg−1, respectively. The radium equivalent activities obtained in the building materials are all well below the acceptable limit.
The indoor gamma-dose has been measured using thermoluminescence dosimeters and it was found in the range of 1051.2–3946.0
μGy/year. The annual effective indoor gamma radiation dose to the people of Gobichettipalayam town has been found to be 0.8
The terrestrial gamma-radiation in soil and sand samples collected around Kudankulam nuclear power plant site, i.e., in Radhapuram
Taluk of Tirunelveli District has been measured using NaI(T1) gamma-ray spectrometer. In the soil samples total dose due to
three primordial radionuclides lies in the range of 13.1–168.2 nGy/h with a geometric mean of 137.2 nGy/h, which yields an
annual effective dose of 0.17 mSv/y. In the sand samples the total dose due to three primordial radionuclides has been found
to be in the range of 38.1–1964.4 nGy/h with a geometric mean of 300.8 nGy/h, which gives an annual effective dose of 0.37
mSv/y which is well below the permissible limit (1 mSv).
The activity concentration and absorbed gamma dose rates due to primordial radionuclides (238U, 232Th and 40K) have been determined for the soil of Coimbatore city using NaI(Tl) gamma-ray spectrometer. The average activity concentrations
of 232Th, 238U and 40K in the soil samples have been found to be 31.4 Bq·kg−1, 12.8 Bq·kg−1 and 698.0 Bq·kg−1, respectively, which give the total gamma dose rate contribution of 56.4 nGy·h−1. Grab sampling technique has been used to determine the indoor radon (222Rn) and thoron (220Rn) progeny levels in different dwellings in the city. The concentrations of radon and thoron progenies range from 0.4 to
10.4 and from 0.7 to 12.7 mWL with a mean value of 1.4 mWL and 3.1 mWL, respectively. The annual effective dose due to radon
and thoron progeny has been found to be 0.14 mSv·y−1.