Electricity generators of varying capacities are popularly utilized in Nigeria as alternative source of power owing to the unreliability of electricity supply through the national grid. This study evaluated the impact of emissions from generating sets on air quality and human health in selected areas of Abeokuta city, Nigeria. The levels of particulates (PM1, PM3), carbon monoxide, carbon dioxide, sulphur oxides, nitrogen oxides, nitrogen dioxide, hydrogen sulphide and methane were monitored using portable samplers. Copies of questionnaire were administered to generator operators and nearby residents so as to collect additional information. The capacities of sampled generators ranged from 1 to 25 kVA. The range of mean concentrations of PM1 (4.7-219.2 mu g/m(3)), PM3 (7.8-251.6 mu g/m(3)), carbon dioxide (4.5-10.9%), methane (0.0-1.2 ppm), carbon monoxide (141.1-4167.0 ppm), NOx (4.0-85.7 ppm), methane (2.3-31.0 ppm), sulphur oxides (3.5-65.6 ppm) and hydrogen sulphide (0.0-0.7 ppm) was highest at generator sites. The distance of sample sites to generator locations accounted for 14-66% variation of pollutants levels. Ailments frequently suffered by the exposed residents included nasal congestion (66%), cough (33%), headache (24%) and fever (12%). A national policy on appropriate use of electricity generator is urgently needed in Nigeria.