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ABSTRACT
Nitrogen dioxide (NO2) is a major air pollutant and an indicator of air pollution, whose ambient concentration in many urban areas continue to breach local statutory limits or the World Health Organisation’s (WHO’s) air quality guidelines. Palmes type passive diffusion tubes (PDT) are widely used for spatial and temporal measurement of nitrogen dioxide concentrations. In this study, the NO2 concentrations and distribution in the University of Benin, Ugbowo campus for outdoor and indoor air have been evaluated. PDT was employed in capturing NO2 in this survey. The samplers were deployed at the specific locations at a height of 2 meters above ground level and changed at two weeks interval. The survey was carried out between November 2021 and December 2021 in accordance with the Department for Environment, Food and Rural Affairs (DEFRA) UK NO2 Diffusion Tube Network Instruction Manual – Version 1.5. Three from each batch were not exposed to the air, and were used to establish the blank value for the whole procedure. A mean NO2 range of 3.17 – 23.24 ppb (6.06 – 44.40µgm3 ) was obtained for all locations 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 highest NO2 level of 23.24ppb (44. 40µgm-3 ) was recorded at sampling site (AQO1) an outdoor site, this site recorded a slightly higher value above the WHO regulatory limit of 40µgm-3 . While the lowest NO2 level of 3.17ppb (6.10µgm-3) was recorded at AQOF1 an indoor site. Outdoor sources were identified as the main source of NO2 at these work places.
