Estimation of Radiation Risks Associated with Radon within Residential Buildings in Okrika, Rivers State, Nigeria

Abstract

The presence of high indoor radon concentration in residential buildings is a major concern of the public worldwide. Measurements of the indoor radon concentration in some selected residential buildings made of different building materials within Okrika local Government Area, in Rives State, Nigeria, was carried out using a Corentium Digital Radon Detector. The maximum mean value of the indoor radon concentration recorded was 19.36 ± 2.26 Bq/m3 for mud houses, and minimum mean value of 09.35±0.78 Bq/m3 for houses made of cemented solid blocks and floored with ceramic tiles, with an overall mean of 11.70 ± 3.28 Bq/m3. This value is below the range of limit of 200 and 600 Bq/m3 recommended by ICRP for residential buildings. Values of the computed annual absorbed dose rate varied from 0.24 ± 0.01 to 0.49 ± 0.03mSvy1, with an overall mean of 0.30 ± 0.08 mSvy-1. This value is lower than the recommended ICRP intervention limit of between (3-10) mSvy-1. The computed annual equivalent dose rate ranged from 0.58 ± 0.02 to 1.17 ± 0.08 mSvy-1, with an overall mean of 0.71 ± 0.20 mSvy-1. This value is lower than the maximum permissible limit of 1 mSvy-1 recommended by ICRP. The computed excess life cancer risk ranged from 2.0 ± 0.07 E - 3 to 4.1 ± 0.28 E - 3, with an overall mean of 2.5 ± 0.07. This value is higher than the world average of 0.29 x10-3. The results of this research have shown that the radiological health risks of the inhabitants living in mud houses are higher compared to those living in other types of dwelling. In addition, measures have to be put in place for effective monitoring. Oil activities, as well as the effluents from multinational companies within its environs, needs adequate monitoring, and the government should encourage the execution of housing scheme projects for the less privilege in order to reduce the radiological risks associated to radon exposure.