Comparison of Indoor Air Quality in Schools: Urban vs. Industrial 'Oil & Gas' Zones in Akwa Ibom State – Nigeria

Abstract

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 (PM 1 , PM 2 , PM 5 , and PM 10), carbon monoxide (CO), carbon dioxide (CO 2) 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/m 3 for PM 1 ; 2744-3207 μg/m 3 for PM 2 ; 137-149 μg/m 3 for PM 5 ; 38-46 μg/m 3 for PM 10 and in urban zone, the concentrations of PM ranged from 1978-2491 μg/m 3 for PM 1 ; 1010-1311 μg/m 3 for PM 2 ; 38-56 μg/m 3 for PM 5 ; 15-24 μg/m 3 for PM 10. During the dry season, the concentrations of PM in the naturally ventilated classroom in industrial zone ranged from 6138-6999 μg/m 3 for PM 1 ; 2984-3980 μg/m 3 for PM 2 ; 146-159 μg/m 3 for PM 5 ; 47-59 μg/m 3 for PM 10 and in urban zone, the concentrations of PM ranged from 2556-3972 μg/m 3 for PM 1 ; 1911-2311 μg/m 3 for PM 2 ; 51-66 μg/m 3 for PM 5 ; 18-34 μg/m 3 for PM 10. Results of this study has revealed that the concentrations of PM 1 , PM 2 , PM 5 , and PM 10 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 PM 10 measured were found to be much lower than the ambient maximum contaminant level for airborne PM 10 standard promulgated by the United States Environmental Protection Agency (US-EPA) (150 μg/m 3 daily average and 50 μg/m 3 annual average) and World Health Organization (WHO) PM 10 guidelines values (50 μg/m 3 daily average and 20 μg/m 3 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 CO 2 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.