Evaluation of concentrations and calculation of effective dose of radon/thoron in cement brick housing in the city of Mounana, south-eastern Gabon
Sylvere Loemba Mouandza, Sylvestre Tsila Saidou, Durastanti-Rabenga Mombo, Shinji Tokonami, Wilfried Ndong, Philippe Ondo Meye and 5 more
Nuclear Technology and Radiation Protection
This study focuses on public exposure to natural radioactivity from radon (???Rn) and thoron (??0Rn), the assessment of the annual effective dose from inhalation, and the estimation of the risk of radon-inducedcancerforpeople living in homes inthe town of Mounana, Gabon. Fifty detectors were deployed in 50 homes in the city of Mounana in the south-east of Gabon. The concentrations obtained varied between 88 ?1 Bqm-3 and 226.4 ?1 Bqm-3 for 222Rn, and between 2 Bqm-3 and 145 Bqm-3 for 220Rn. The arithmetic and geometric mean values determined were respectively 123.9 ?4.3 Bqm-3 and 121.4 ?1.1 Bqm-3 for 222Rn, 21.3 ? 25 Bqm-3and 13.2 ?1.12 Bqm-3 for 220Rn. Thoron concentrations were below 100 Bqm-3? and in 50 % of cases below 10 Bqm-3, the global reference value. The geometric and arithmetic mean values for radon were 3 to 4 times higher than the global arithmetic and geometric mean values recommended by UNSCEAR (40 Bqm-3 and 30 Bqm-3). The annual effective inhalation doses vary between 1.6 mSv and 4.3 mSv for 222Rn, witha mean of 2.4 mSv, and between 0.1 mSv and 3 mSv for 220Rn, witha mean of 0.6 mSv. Unlike thoron, radon concentrations exceeded 100 Bqm-3 in 89 % of homes, which is above the reference level set by the world health organization.