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.
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