Science and Education Publishing Journal of Atmospheric Pollution 3 1 2015 04 14 Outdoor Radon Concentration in the Township of Ado-Ekiti Nigeria 18 21 EN OJO T.J Department of Science Technology, Federal Polytechnic, P.M.B 5351, Ado-Ekiti, Ekiti State, Nigeria AJAYI I.R JAP2015314 10.12691/jap-3-1-4 2015 04 03 2015 04 11 2015 04 14 Solid State Nuclear Track Detectors (CR-39) were used for the measurement of outdoor 222Radon concentration in 30 locations in the township of Ado-Ekiti Nigeria. The annual effective dose of radon and its progenies to the residents was calculated from the results of the measurement. The concentrations of radon varied from 2.22 to 92.50 Bq m-3 with an overall mean of 29.57 Bq m-3. The annual absorbed dose was found to range from 0.09 to 3.81 mSv y-1 with an average of 1.18 mSv y-1. The estimated annual effective dose to lung ranged from 0.22 to 9.14 mSv y-1 with an average of 2.88 mSv y-1. The values measured for Radon concentration were found to fall below the upper limit of the ICRP reference level.