In this paper we present the results of four years of field measurement data of the radiation from global systems for mobile (GSM) base stations and commonly used mobile phones across Nigeria. We evaluate the electric field strengths, the power densities, and the specific absorption rate (SAR). The radiated intensities were compared to the international standard limit of 200 .W/cm2 and were found to be far below the set limit. The highest intensity level was 5.94 nW/cm2 from a mobile base station. However, the average radio frequency exposure levels from GSM base stations were considerably lower at 0.806 nW/cm2, 0.0.451 nW/cm2, and 0.236 nW/cm2 for Globacom, MTN, and V-Mobile, respectively. We note that these measured, low, power densities from GSM base stations and mobile phones are safe only when considering thermal effects of these radiations. However, our findings from an epidemiological viewpoint show that there are associated health effects with these levels of radiation, which are purely non-thermal.