Assessment of radiological dose from exposure to attached and unattached fractions of radon ( 222 Rn) and thoron ( 220 R
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Assessment of radiological dose from exposure to attached and unattached fractions of radon (222Rn) and thoron (220Rn) in indoor atmosphere S. Suresh1 · D. R. Rangaswamy2,3 · J. Sannappa3 · E. Srinivasa4 Received: 21 February 2020 © Akadémiai Kiadó, Budapest, Hungary 2020
Abstract In this study pin hole dosimeter with deposition based progeny sensors were used to estimate 222Rn, 220Rn and their daughters in the indoor atmosphere. The estimated annual average indoor 222Rn and 220Rn activity concentration were found to be 76.4 Bq m−3 and 93.5 Bq m−3, respectively. The mean value of EEC for radon and thoron was 45.5 Bq m−3 and 1.3 Bq m−3 respectively. The annual effective dose due to indoor 222Rn and 220Rn were found to be 2.9 mSv y−1 and 0.4 mSv y−1 respectively. The estimated effective doses are well below the safe limit as suggested by ICRP for indoor exposure. Keywords Equilibrium equivalent radon concentration · Equilibrium equivalent thoron concentration · Attached and unattached fractions · Equilibrium factor · Radiological hazards · Coastal Uttara Kannada
Introduction Nearly 52% of radiation dose to mankind is attributed by inhalation of 222Rn, 220Rn and their progenies [1, 2]. Radon and thoron are the naturally occurring radionuclides formed by the disintegration of their parents uranium and thorium present in building substances, distinct kinds of rocks and soils. The indoor radon is taken into consideration as the second maximum essential reason for lung cancer in general public after smoking [2]. Hence it is very essential to monitor the activity level of these radionuclides in indoor environment. On the basis of epidemiological research in different nations, the WHO has insisted to reduce the radon action level from 200 to 100 Bq m−3 [3]. This recommendation creates a curiosity among researchers in radon study * J. Sannappa [email protected] 1
Department of Physics, M.P.E Society’s S.D.M Degree College, Honavar 581334, India
2
Department of Science and Humanities, PES University Electronic City Campus, Bangalore 560100, India
3
Department of Studies and Research in Physics, Kuvempu University, Shankaraghatta, Shivamogga 577451, India
4
Department of Physics, IDSG Government College, Chikkamagaluru 577102, India
and large-scale radon mapping programme all over the globe are initiated to estimate the radon hazards in general public. Because of its quick half life, thoron has been neglected in the early studies [4]. But it has significant effect in those areas where in the background radiation level is high and the soil has high concentration of thorium. From the epidemiological point of view the priority must be given to these areas to estimate the low-level chronic exposure of radiation on human health [5]. The major contributors to lung doses are radon and thoron progenies but not 222Rn and 220Rn. Therefore, it is very essential to estimate the progenies directly. The progenies possess more diffusivities and stretch to form clusters and then to attach on the surfaces. Because o
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