Assessment of air pollution and health hazard associated with sawmill and municipal waste burning in Abeokuta Metropolis, Nigeria

Indiscriminate disposal and open burning of sawmill and municipal solid wastes constitute hazards to the quality of the immediate environment and human health. This study assessed the levels of pollutants emitted by burning sawmill and municipal wastes, and their potential hazards. Nine selected sawmills and 6 municipal solid-waste dumps in Abeokuta metropolis were investigated. During waste burning, the concentrations of NO₂, SO₂, CO, H₂S, NH₃ and VOC were monitored in replicates at the dumpsites, 10 m, 20 m and the nearest houses using portable samplers (Aeroqual and Multi-RAE). Mean, ANOVA, correlation and regression statistical tools were used to analyse air quality data; air quality index (AQI) was employed to classify the hazard rating of the gaseous pollutants. Nearest neighbour analysis in ArcGIS 10.0 was used to investigate dumpsites location pattern within the city. The concentrations (mg/m³) of sampled parameters from source to nearest house (NH) at the dumpsites ranged as follows: < 0.002–0.175 (NO₂), < 0.002–0.235 (SO₂), 0.065–0.425 (H₂S), 13.98–47.40 (CO), 6.74–170.41 (NH₃) and 31.13–820.03 (VOC) in wet and dry seasons. The mean concentrations of NO₂, SO₂ and VOC were below permissible limits at most locations while CO values were higher at all dumpsite. Significant variations (p < 0.05) were observed in the concentrations of the monitored parameters except NO₂ values (SMW) in dry season. AQI rated NO₂ and SO₂ concentrations as “good” at all sites while CO emission ranged from unhealthy to hazardous across the dumpsites. In conclusion, the present locations of SMW and MSW dumps in the city degrade environmental quality and are unsafe for human health.