Outdoor air particle-bound trace metals in four selected communities in Ibadan, Nigeria.

Trace metal concentrations were determined in particulate matter (PM10) in ambient air of four purposively selected residential areas in Ibadan, Nigeria namely Bodija market (BM), Ojo Park (OP), Oluyole Estate (OE) and University of Ibadan (UI). PM10 was determined in the morning (7-10 a.m.) and afternoon (2-5 p.m.) for 12 weeks in the dry season months of January-March using a volumetric sampler following standard procedures and levels compared with WHO guideline limits. Glass-fibre filter papers exposed to the particulate matter were digested using appropriate acid mixtures, and the digest analysed for trace metals including Ni, Cr, Mn, Zn, and Pb using ICPMS method and levels compared with WHO limits. Data was analysed using ANOVA and Pearson correlation test at 5 % level of significance. The highest mean PM10 concentrations 502.3 ± 39.9 µg/m(3) were recorded in the afternoon period at BM, while the lowest concentration 220.6 ± 69.9 µg/m(3) was observed in the morning hours at UI. There was a significant difference between the PM10 levels across the various locations (p < 0.05), and all the levels were higher than WHO limit of 50 µg/m(3). The highest levels of Ni, Zn and Pb were recorded at BM, which also had the highest PM10 burden. The trend in Pb levels across the locations was BM > UI > OP > OE with the highest level 5.70 µg/m(3) in BM nearly fourfolds WHO limits of 1.5 µg/m(3). There was a significant correlation between PM10 and Ni (p < 0.05).Urban communities with increased human activities especially motor traffic recorded both higher levels of PM10 and toxic trace metals. There is need to carry out source apportionment to establish the origin of these trace metals in future studies.

Outdoor respirable particulate matter and the lung function status of residents of selected communities in Ibadan, Nigeria.

BACKGROUND: Ambient air pollution remains a major public health hazard in urban communities. In Nigeria, air quality management especially in the urban centres, is fraught with enormous challenges including limited data. We assessed the outdoor respirable particulate matter (PM10) concentration and the pulmonary function status of residents in four selected communities in Ibadan. METHODS: A cross-sectional study design was employed. Four locations - Ojoo Park (OP = high traffic area), Bodija Market (BM = commercial area), Oluyole Estate (OE = industrial area) and the University of Ibadan (UI = academic community - reference) - were selected based on varying intensities of urban activity. PM10 levels were recorded in the morning and afternoon for 12 weeks between January and March 2008. Lung function status (FEV1) of 140 randomly selected participants was measured. Daily mean of PM10 levels were compared with WHO guideline limits. Data analysis was done using descriptive, χ(2), ANOVA and Spearman-rank correlation tests at 5% level of significance. RESULTS: For all sites, PM10 concentration was generally higher in the afternoon. The highest daily mean PM10 concentration was recorded at BM, followed by OP, OE and UI. These values when compared with WHO guideline limits showed: BM eightfold > OP sevenfold > OE sixfold > UI fivefold (p < .05). Weekly mean PM10 levels and mean FEV1(obs) gave the following order: UI > OE > OP > BM. There was a significant negative correlation between PM10 burden and FEV1(obs) across the study locations (r =-0.371, p < .05). CONCLUSION: Most of the locations with higher particulate burden were observed to have declining lung function status. A longitudinal study to establish more robust associations is advocated.