Aniefiok E. Ite^{1, 2,}, Thomas A. Harry³, Clement O. Obadimu¹, Ifiok O. Ekwere¹

This study was carried out to assess indoor air quality (IAQ) in schools in Akwa Ibom State of Nigeria during the rainy (June – July) and dry (November – December) seasons of 2018. IAQ parameters were examined to assess pollutant levels in schools within Akwa Ibom State in single setting only (naturally ventilated classrooms). Schools were randomly selected from two zones: zone 1 which is located within the Capital City (Uyo metropolis) and represents the 'urban sector', and zone 2 which is located within the southern part of the state in close proximity to the oil and gas industrial region and represents the 'industrial sector'. Indoor air investigation included the following parameters: particulate matter (PM₁, PM₂, PM₅, and PM₁₀), carbon monoxide (CO), carbon dioxide (CO₂) levels, temperature and relative humidity, which were simultaneously measured in fourteen (14) sampling days using Fluke 985 Particle Counter and Fluke 975 AirMeter. Multiple statistically analysis techniques were used to compare IAQ parameters and test for significant differences between the zones (urban vs. industrial) and annual seasonal variations. The concentrations of particulate matter (PM) in the naturally ventilated classroom in industrial zone during the rainy season ranged from 5152 – 5984 μg/m³ for PM₁; 2744 – 3207 μg/m³ for PM₂; 137 – 149 μg/m³ for PM₅; 38 – 46 μg/m³ for PM₁₀ and in urban zone, the concentrations of PM ranged from 1978 – 2491 μg/m³ for PM₁; 1010 – 1311 μg/m³ for PM₂; 38 – 56 μg/m³ for PM₅; 15 – 24 μg/m³ for PM₁₀. During the dry season, the concentrations of PM in the naturally ventilated classroom in industrial zone ranged from 6138 – 6999 μg/m³ for PM₁; 2984 – 3980 μg/m³ for PM₂; 146 – 159 μg/m³ for PM₅; 47 – 59 μg/m³ for PM₁₀ and in urban zone, the concentrations of PM ranged from 2556 – 3972 μg/m³ for PM₁; 1911 – 2311 μg/m³ for PM₂; 51 – 66 μg/m³ for PM₅; 18 – 34 μg/m³ for PM₁₀. Results of this study has revealed that the concentrations of PM₁, PM₂, PM₅, and PM₁₀ measured in the naturally ventilated classroom in industrial zone were significantly (p < 0.001) higher than those measured in the urban zone during both rainy and dry seasons. In this present study, the concentrations of PM₁₀ measured were found to be much lower than the ambient maximum contaminant level for airborne PM₁₀ standard promulgated by the United States Environmental Protection Agency (US–EPA) (150 μg/m³ daily average and 50 μg/m³ annual average) and World Health Organization (WHO) PM₁₀ guidelines values (50 μg/m³ daily average and 20 μg/m³ annual average). Apart from re–suspension of atmospheric particles, anthropogenic activities in industrial zone significantly influenced the measured concentrations of PM compared to those measured in urban zone. In addition, the lower concentration of CO and CO₂ measured indicated adequate air exchange at the time of the assessment in the naturally ventilated classrooms during the sampling period. The results obtained reveal important contributions towards understanding of airborne PM distribution patterns and the available data can be used for making public health policies.

indoor air quality, particulate matter, schools; exposure, Akwa Ibom State, Nigeria