Agora, Jared OmariHashim, Nadir Omar2023-07-052023-07-052015Agora, J. O., & Hashim, N. O. (2015). Assessment of Radioactivity Levels and Risks Due To Different Rock Types from the KERIO Valley “High Background Radiation Area (HBRA)” of Kenya. Int J Math Phys Sci Res, 3(1), 40-47.2348-5736http://ir-library.ku.ac.ke/handle/123456789/26071articleThe goal of this study was to analyse the natural radioactivity levels and assess the contribution of different rock types to environmental dose in the Kerio Valley region of Kenya, a suspect high background radiation area (HBRA). The activity concentrations of 238U, 232Th and 40K in granite, sandstone, tuff, limestone, quartzite, gneiss, marble and conglomerate rocks were found to vary from 72.70 8.47 Bqkg-1-116.15 11.46 Bqkg-1, 40.32 14.48 Bqkg-1- 83.65 9.91 Bqkg-1 and 427.41 48.23 Bqkg-1-1397.24 65.27 Bqkg-1 respectively. Radium equivalent activity and external hazard index show that all the rock types do not exceed the recommended limit of 370 Bqkg-1 and 1, respectively. Calculated outdoor absorbed dose rate ranged from 90.585 nGyh-1 (limestone) to 159.085 nG/h (quartzite) while the indoor absorbed dose rate ranged from 66.696 nGyh-1(limestone) to 157.442 nGyh-1 (quartzite), which are above the world average value of 60nGy-1. The annual effective dose rate analysis is also presented.enNatural radioactivityrock typesgamma spectrometryradium equivalent activitygamma indexdose ratesArticle