Indoor radon concentration levels in some selected offices at Ibrahim Badamasi Babangida University, Lapai, Nigeria and its attendant annual effective dose

Although radon concentrations in outdoor environments are generally low, the indoor concentrations can become appreciably high thereby affecting the indoor air quality and causing some severe health challenges. Thirty (30) offices from the ground floor and first floor of some buildings within Ibrahim Badamasi Babangida (IBB) University campus, Lapai Nigeria, were randomly selected for indoor radon concentration (CRn) measurement using RAD7 continuous radon monitor. Annual effective dose was also computed to determine the level of public exposure. The results showed that radon concentration values for all the offices on the ground floor ranged between 9.6±2.7 Bqm−3 and 90.7±8.1 Bqm−3, with mean value of 28.5±4.8 Bqm−3 while the range of radon concentration at first floor was 2.5±1.4 Bqm−3 - 80.4±7.5 Bqm−3. All the measured indoor radon concentration levels were less than the 100 Bqm−3 action level proposed by World Health Organization (WHO). Average annual absorbed dose for both ground and first floors were 0.36±0.06 mSvy−1 and 0.24±0.05 mSvy−1 respectively, with corresponding mean annual effective dose of 0.86±0.15 mSvy−1 and 0.58±0.11 mSvy−1 in sequence. These values were below the 1.0 mSvy−1 safety limit set for public. Although the results did not suggest any immediate exposure threat to the public, it is important that the University staffs are adequately informed of indoor radon levels and its attendant health hazards. Improved and adequate ventilation of all the office buildings is highly encouraged in order to keep the radon levels as low as reasonably achievable (ALARA).