Activity concentrations of 40K, 232Th, 226Ra and radiation exposure levels in Nairobi Central business district and the industrial area

Radiation levels were determined using a handheld meter device model Horiba PA- 1100. Soil samples were also collected and analyzed using gamma spectrometry. Radionuclides present were identified. The activity concentration for 232Th and 226Ra ranged between 21.1878±0.22 to 163.323±0.32 and 34.5543±0.03 to 198.467±0.14 Bqkg-1 respectively. The mean air absorbed gamma radiation dose rate (D) was 156.1788366 nGyh-1, 4 times higher than the world average value of 43 nGyh-1. The average measured absorbed dose rate for the sampled sites was 1064.9229 nGyh-1, 17 times higher than the world average value of 60 nGyh-1. Mean values for External and Internal hazard indices were 0.880899 and 1.086053 respectively compared to the standard unity value (?1). Average annual effective dose rate calculated from the soil sample was 0.957689 mSvy-1. Nairobi and it’s environ are highly polluted with radiative materials. The data partly explains the high incidences of cancer related diseases within the study area. The aim of this study is to enhance documented radiation data in Kenya which is important in creating awareness and assessing radiation related diseases, towards achieving global radiation reduction.