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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]