Spatial and Diurnal Variations of Carbon Monoxide (CO) Pollution from Motor Vehicles in an Urban Centre
Emmanuel Ehiabhi Ukpebor1, Justina Ebehirieme Ukpebor2, Felix Eromomene1, Justice Ighodaro Odiase3, Duke Okoro4
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1Department of Chemistry, Air Pollution Research Group, University of Benin, Benin City, Nigeria
2Department of Environmental Science, Lancaster University, Lancaster, LAI, 4YQ, UK
3Department of Mathematics, University of Benin, Benin City, Nigeria
4Department of Chemistry, Delta State University Abraka, Nigeria
Pol. J. Environ. Stud. 2010;19(4):817–823
In the months of May and June, 2008, about 20 deaths from CO poisoning were reported in Nigeria. Ignorance along with lack of information and data about this toxic substance can be blamed for these deaths. In this study, a preliminary attempt is made to evaluate the diurnal trend in CO generation and distribution at several road junctions and motor parks in Benin City. A dosimeter (in situ method) that uses an electrochemical sensor to measure ambient levels of CO was used. At the 5 sampling locations selected, very high CO concentrations were measured with a mean range of 14.8-28.3 ppm. The 10.0 ppm statutory limit set by the Federal Ministry of the Environment, Housing and Urban Development (FMEH&UD) was clearly exceeded. Diurnal variations in the data were statistically significant (P < 0.05), with the highest CO concentrations recorded in the morning hours. Spatial variations were also statistically significant, with the highest mean CO load of 28.3 ppm measured at Sokponba road junction. Vehicular exhaust was identified as the main CO source in the city. Frequent traffic jams resulting from poorly maintained roads, high traffic density, unfavourable traffic handling, inadequate traffic discipline and very low wind speed are identified as the main factors responsible for the high emissions, accumulation, and low dilution and dispersion of the generated CO.