Diurnal variations of carbon monoxide (CO) pollution from motor vehicles in an urban centre in Nigeria using a CO dosimeter

Author(s): E.E.Ukpebor, J.E.Ukpebor, F.Eromomene, J.I.Odiase, D.Okoro

In the months of May and June, 2008, about 20 deaths from CO poisoning were reported in Nigeria national dailies. Ignorance and dearth of information and data about this toxic substance have been suggested for this ugly trend. In this study, a preliminary attempt was made to evaluate the diurnal trend in CO generation and distribution at several road junctions andmotor parks in BeninCity.Adosimeter (in-situmethod) which uses an electrochemical sensor to measure ambient levels of CO was used. At the 5 sampling locations created, very high CO concentrations were measuredwith amean range of 14.8 – 28.3 ppm. The 10.0 ppmstatutory limit set by the Federal Ministry of Environment, Housing and Urban Development (FMEH&UD)was clearly exceeded. Diurnal variations in the data were significant (P < 0.05) with the highest CO concentrations recorded in the morning hours. Spatial Variations were also significant,with the highestmeanCOload of 28.3 ppmmeasured at Sokponba road junction.Vehicular exhaustwas identified as themain COsource 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 were identified as largely responsible for the high emissions, accumulation and low dilution and dispersion of the generated CO.

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