Comparison of Public Indoor Internal Exposure from Radon-222 Inhalation in the Different Dwellings of 09 Regions of Madagascar

Radon is the radioactive gas naturally present in the environment produced by natural radioactive decay of uranium-238. It is uncolored and inodorous and present in outdoor air as well as in dwelling spaces. In nine (09) regions of Madagascar, radon study was carried out for indoor radon concentration measurement in 62 dwellings spread. The aim of this study is to compare the indoor internal exposure due to Radon inhalation. AphaGuard and SARAD equipment were used. The radon concentration and the annual effective dose vary respectively from (4.37 ± 1.74) Bq.m<sup>-3</sup> to (77.80 ± 4.51) Bq.m<sup>-3 </sup>with average value of (31.04 ± 7.78) Bq.m<sup>-3</sup> and from (0.14 ± 0.05) mSv.y<sup>-1</sup> to (2.45 ± 0.14) mSv.y<sup>-1 </sup>with average value of (0.98 ± 0.18) mSv.y<sup>-1</sup>. The average value of Lung Cancer Case (LCC) per year and per million persons was found at 17.62. The average radon concentration is lower than the WHO, UNSCEAR 2000, and GSR Part N°.3 Public limit value, however, its contribution to the total exposition to the population is significant. It has been found that all the obtained results during this works vary across regions. The Region of Vakinankaratra represents the highest effective average value of annual high effective dose and radon concentration due to high uranium potential of this region. Analanjirofo and Antsinanana regions represent the lowest annual effective dose and radon concentration due to the abundance of Th-232 concentration than Uranium in these regions.