Quantification of mass concentrations aerosols PM2.5 in primary schools. A case study: Tiaret city (Algeria)

Abstract

For the study purposes, 23 primary schools have been selected in Tiaret city, and the collection of PM2.5 was performed in the morning, afternoon and evening, in the presence and absence of students. The results showed a gradient of concentrations of PM2.5 by site typology. Low and average concentrations are recorded in the areas close to forests (23.32 ± 2.77 µg/m3) and high concentrations are observed in the sites exposed to road traffic (33.57 ± 3.27 µg/m3) in winter. However, concentrations recorded in the urban sites are lower in the summer (25.33 ± 2.85 µg/m3 in sites exposed to road traffic, and 23.78 ± 1.92 µg/m3 in sites close to the forests). We also noticed that the dominance of PM2.5 was observed in the vicinity of the major axes of movement. The dispersion of these particles is illustrated by detailed maps. The maps present information obtained by hierarchical classification. They aim to answer the need for spatial knowledge of the problem of particulate pollution in urban areas in the city of Tiaret. The hierarchical classification allowed distinguishing three groups of schools: Urban schools, urban schools highly subject to dense road traffic and schools close to green spaces and forests. The results obtained revealed a high contamination of the atmospheric environment of the city of Tiaret by PM2.5 aerosols, taking into account the results recorded in primary schools. Mass concentration of PM2.5 in the first period (autumn and winter) is higher than that of the second period (spring and summer). Indeed, the highest concentrations are recorded in the presence of students in winter.