Author(s)

Sylvanus A. Onjefu^1,2*, Nnenesi A. Kgabi³, Simeon H. Taole¹, Owen P. L. Mtambo⁴, Charles Grant⁵, Johann Antoine⁵

¹Department of Physics and Electronics, North-West University, Mafikeng Campus, Mmabatho, South Africa.
²Department of Natural and Applied Sciences, Namibia University of Science and Technology, Windhoek, Namibia.
³Department of Civil and Environmental Engineering, Namibia University of Science and Technology, Windhoek, Namibia.
⁴Department of Mathematics and Statistic, Namibia University of Science and Technology, Windhoek, Namibia.
⁵International Centre for Environmental and Nuclear Sciences, University of the West Indies, Mona Campus, Kingston, Jamaica.

In this study, an occupancy factor model was developed and used to calculate the average time spent for outdoor and indoor activities along the coastline of the Erongo region of Namibia. A closed ended questionnaire was developed and administered to 800 respondents who visited the coastline for leisure, occupational and other activities. The mean time allocated for leisure activities ranges from 13.00 to 1.00 h, occupational mean time between 10.18 to 9.06 h and the values of other activities range from 16.66 to 11.00 h. The average computed time spent outdoor was found to be 11.46 h and indoor calculated to be 12.54 h. This shows an outdoor factor of 0.48 and indoor factor of 0.52 respectively. From the results obtained, the value of the absorbed dose rate ranged from 93.27 to 105.95 nGy·h^-1 and the annual effective dose rate ranged from 121.01 to 176.61 μSv·y^-1 (UNSCEAR factor) and 292.60 to 413.63 μSv·y^-1 (present factor). The values obtained for annual effective dose are higher than the acceptable limit. However, from this study, we can conclude that the use of the UNSCEAR outdoor factor in the coastline will lead to underestimation of effective dose by 24% based on the present factor.

Model, Indoor, Outdoor, Leisure, Occupation, Effective Dose

Onjefu, S. , Kgabi, N. , Taole, S. , Mtambo, O. , Grant, C. and Antoine, J. (2016) Occupancy Factor Model for Exposure to Natural Radionuclides along the Coastline of Erongo Region, Namibia. Journal of Geoscience and Environment Protection, 4, 117-126. doi: 10.4236/gep.2016.45012.