The paucity of data on air pollution indices in Nigeria prompted us to commence a national screening exercise regarding particulate matter loads. Six potential megacities (Aba, Abuja, Lagos, Kano, Maiduguri, and Port-Harcourt) representing the six geographical zones in Nigeria were chosen for the study. Sampling was achieved using a 'Gent' stacked filter unit sampler capable of collecting fractions of particulate matter with sizes of <10-mm and <2.5-mm simultaneously. The mean values for PM 10 are 550, 35, 87, 340, 246 and 130 mg m À3 while for PM 2.5 the mean values are 100, 14, 25, 67, 20 and 30 mg m À3 respectively for Aba, Abuja, Lagos, Kano, Maiduguri, and Port-Harcourt. Except for Abuja, the daily PM 10 mass loads exceeded the World Health Organization (WHO) guidelines daily limit where as the PM 2.5 values were within the WHO guideline limit. Their correlation matrix result indicates that some PM 2.5 fractions mass fractions were strongly correlated than the PM 10 fractions probably due to their long range transport potentials. Further work is in progress to determine the elemental profiles of both particulate fractions collected.

Ambient concentrations of PM 10 (x 10 mm) and PM 2.5 (x 2.5 mm) particulate fractions collected from Ikoyi Lagos, Nigeria, as well as their elemental compositions are presented in this study. Both size-segregated fractions were collected using a double staged 'Gent' stack filter unit sampler. Elemental characterizations of dust laden filters were carried out using proton-induced X-ray emission (PIXE) technique. Twenty-two elements (Si, S, Cl, K, Ca, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Pb, Br, Rb, Sr, Zr, Ag, Cd, and Ta) were detected as well as their concentrations and correlations were determined for both particulate size fractions. Their correlation matrix result indicates that some of the trace elements detected could have common source origins or similar chemical properties. The results were similar to the levels observed in moderately polluted urban areas and there is need for source identification and apportionment using receptor models in future studies.

No abstract

No abstract

No abstract