Indoor radon concentrations in the dormitories of selected secondary schools in Otuke District, Northern Uganda

Abstract

Inhalation of radon and its progeny is the most significant source of natural radiation exposure to human population. Over 50 % of the natural background radiation comes from radon (222Rn). This study measured background radiations, determined indoor radon concentrations and assessed the effective dose to students due to radon inhalation in the dormitories of five selected boarding secondary schools in Otuke District. Background radiations in the dormitories were measured using survey meters. Radon concentrations were determined using activated charcoal canister method. Effective doses were calculated basing on radon concentrations in the dormitories. Data collection was done for a period of seven months; between September 2016 and March 2017, and between April and May 2018. Background radiation in counts per second (cps) was found to range from 0.8±0.2 to 1.7±0.3 with an average of 1.2±0.2 cps. Radon concentrations were in the range of 18±3 Bq m−3 to 49±5 Bq m−3 with an average of 30±4 Bq m−3 and annual effective dose ranged from 0.14±0.02 mSv y−1 to 0.39±0.04 mSv y−1 with a mean of 0.24±0.02 mSv y−1. Radon concentrations found in this study were below the World Health Organization (WHO) action level of 100 Bq m−3 and the mean effective dose was well below 1.0 mSv y−1 which is the dose limit set for members of the public by the International Commission on Radiological Protection (ICRP). Basing on these set limits, students sleeping in the studied dormitories are not exposed to high doses of indoor radon and are therefore safe. It is recommended that, strategies for radon prevention in new dormitories could be put in place to further reduce radon concentrations in the studied schools below the values reported and a national radon survey be done to establish a reference radon level for Uganda, upon which comparison can be made.