核医学と放射線治療

Determination of Background Ionizing Radiations in Selected Buildings in Nairobi County, Kenya

Abstract

Ogola PE, Arika WM, Nyamai DW, Osano KO, Rachuonyo HO, Wambani JR, Lagat RC, Njagi SM, Mumenya SW, Koteng’ A, Ngugi MP and Oduor RO

A survey taken by the world health organization (WHO) and the international commission on radiation protection (ICRP) shows that certain materials used for the construction of such buildings (rocks soils) are known to be radioactive. Exposure to indoor ionizing radiation like exposure to any other type of ionizing radiation results in critical health challenges. This work set out to determine the levels of background ionizing radiations in selected buildings around Nairobi County and its environs. The Radiation Alert R (Digilert 200) meters were used to capture the readings. The meters were held about 1 m above ground level and readings were recorded in mR/h for all buildings. Numerical data was subjected to analysis of variance using Minitab version 17.0 to determine the statistical differences of exposure levels within various areas. A total of 400 buildings were sampled. The annual indoor readings were highest in Eastleigh (4.070 mSv) and relatively lowest in Nairobi Central Business District (CBD) at 2.763 mSv, representing a deviation from WHO recommended standard of 307.0% and 176.3%, respectively. None of the buildings sampled had exposure levels below the WHO recommended standard of 1 mSv. Overall, these results indicate presence of higher levels of ionizing radiations in buildings beyond the acceptable annual threshold thereby posing significant health risk to the public. Consequently, these results could find great application in guiding the formulation of the national building code to include routine surveillance of the background ionizing radiation levels in various buildings to assess the health risk of general public as well as exploring appropriate mitigation approaches.