Assessment of Vehicular Carbon Dioxide Emission at Major Road Intersections in Benin City, Edo State Nigeria

This study examines the levels of vehicular Carbon (IV) oxide (CO2) emissions in nine (9) selected locations characterised by high traffic congestion in Benin City Metropolis, Edo State, Nigeria. The contributory effects of these emission levels on climate change and air pollution were also assessed based on global standards. CO2 concentration measurements were conducted twice a day, four times a week, for a period of sixteen (16) weeks. Results showed that the highest average mean values were recorded at Ring Road, New Benin and Third East Circular Junctions with 1421 ppm, 1417ppm and 1171ppm respectively in the morning hours and 1767ppm, 1417ppm, 1217ppm respectively in the afternoon hours. Diurnal variations revealed significant statistical differences (P<0.05) for CO2 emissions generated at different times of the day. Spatial variations in the CO2 data were also statistically significant (P<0.05), with the highest mean concentrations of 1594ppm reported for Ring Road sampling station while New Benin and Five Junction sampling sites recorded mean CO2 emissions rates of 1417ppm and 745.8ppm respectively. The results showed that CO2 emission levels at these selected high traffic areas in Benin are approximately five times more than the internationally accepted safe limits of 350ppm for atmospheric CO2. However, these levels are less than the Occupational Safety and Health Administration (OSHA) permissible exposure limits of 5,000ppm. High vehicular exhaust emission which is the primary source of CO2 in the Benin city metropolis can be attributed to poor traffic handling and discipline; and low dilution and dispersion of the emitted CO2 due to prevalent low wind speeds in these study locations.