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Baseline nitrogen dioxide (NO2) concentration and distribution in 10 offices in Benin City, Nigeria have been evaluated. Palmes diffusion tubes were employed in capturing NO2 data in this survey. The diffusion tubes were deployed at the specific offices at a height of approximately 2.0 m above the floor, and changed at two-week intervals. The survey was carried out between May and July 2005 in accordance with the Department for Environment, Food and Rural Affairs (DEFRA) UK NO2 Diffusion Tube Network Instruction Manual - Version 1.5. A NO2 range of 1.89 µgm-3-24.83 µgm-3 was obtained for the offices studied which indicate good compliance with the available National and International regulatory limits for NO2. Significant spatial variations (p < 0.05) were noticed in the NO2 distribution. The Principal Component Analysis (PCA) identified several clusters of NO2 and different degrees of correlation between the monitoring sites. Outdoor sources were identified as the main source of NO2 at these work places. [ABSTRACT FROM AUTHOR]

In 2004, through the assistance of the World Bank, air quality monitoring equipment was supplied from the United Kingdom and United States to Edo State Ministry of Environment in Nigeria. Amongst the air pollution assessment tools supplied, are a portable SKC 506673 high volume Gravimetric Sampler and a light‐scattering method – Haz–Dust™ 10 µm particulate monitor – for airborne particles. In this preliminary study, the two samplers were co‐located at different monitoring sites in Benin City to assess spatial distribution of airborne particles and also to ascertain the collection efficiencies of these monitoring tools. Preliminary results available indicate the non‐compliance of the TSP (Total Suspended Particulates) load obtained at the created monitoring sites with the regulatory limits of 150–230 µgm-3 and 250 µgm-3 set by WHO (World Health Organization) and FMENV (Federal Ministry of Environment) respectively. Differences in the collection efficiencies of these samplers were observed with a coefficient of determination (R2) value of 0.6289 obtained. The principal component analysis (PCA) showed different degrees of correlation between the monitoring sites. Two principal components were identified for the particulate matter distribution by the combined methods, which were further confirmed by the hierarchical cluster analysis. Vehicular exhaust, industrial emissions, combustion of solid wastes, dusts from roads and harmattan dust were identified as the major particulate matter sources at these market environments. [ABSTRACT FROM AUTHOR]