Spatio-Temporal Variations in Urban Vehicular Emissions in Uyo City, Akwa Ibom State, Nigeria

The increasing volume of road traffic and congestion strongly impact on air quality in most urban areas of the developing countries. This paper therefore investigates pollution from automobiles during traffic peak periods at intersections on some selected roads in Uyo, Nigeria. It estimates the level of some selected air pollutants which are largely products of internal combustion in motor vehicle engines, namely- Nitrogen dioxide (NO2), Carbon monoxide (CO), Sulphur dioxide (SO2), and Hydrogen sulphide (H2S), in six sample locations. Monitoring of ambient hourly concentration of NO2, CO, SO2 and H2S, took place at six major intersections in Uyo during morning and evening (peak traffic hours) and afternoon (off-peak hours), hence variations in concentration of these pollutants was determined. Emissions concentration for CO, was found to be higher during the peak periods due to traffic congestion and intersection, where long waiting time for vehicles were observed and however exceeded the Federal Ministry of Environment limits / Standards. Also, the concentration of SO2 was alarmingly high, especially in location C. Levels of Nitrogen oxides (NO2) and Hydrogen sulphide (H2S) measured, varied in time and space and was also above the recommended municipal and international standards in all the six locations during the peak traffic period. This finding thus has implications for public health in the region under study as such calls for the need to control emissions of these obnoxious air pollutants in the city.