Baseline concentrations of nitrogen dioxide in offices in residential areas of Benin City, Nigeria

Abstract

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.

Keywords:

• Diffusion tubes
• Nitrogen dioxide
• Work places
• Principal component analysis

Acknowledgement

The passive samplers used in this study were donated by Prof. (Dr) H. Heydtmann of the Institute of Physical and Theoretical Chemistry, Johann Wolfgang Goethe‐Universitat, Frankfurt am Main. We are also grateful to Mr P. Obozekhai for helping with the analysis of the samplers.