Temporal variation of surface O3, NOx and PM10 and associated human health risk in Gabès suburban (South-Eastern Tunisia): multi-scales impact of sources and meteorology

Abstract

The study of daily and hourly average concentrations variability of surface O3, NO, NO2 and PM10 was carried out at the proximity of a crossroad (≈23,000 vehicles per day) located in suburban Gabès, Tunisia. It was performed during 2017–2019 “winter/spring” seasonal transitions and spring seasons. Depending on multi-scale sources and meteorology, it showed variable values ​​within each studied annual period and the years. Statistical approaches based on factorial analysis of correspondences (FAC) and principal component analysis (PCA) revealed three main components of pollution; local retraced by NOx, regional by O3 and synoptic by PM10. Furthermore, they have refined the significant impacts of Saharan dust advections on high recorded PM10 and NOx (by drained urban plume) and of both deep depressions (cut-off lows) and Azores anticyclonic events on the excess of surface O3 concentrations. The investigation of the air quality health index (AQHI) related to the selected pollutants highlighted the significant effect of PM10. It has revealed that more than 53% of the total days were retraced by a moderate air quality index level linked to the negative impact of PM10. Besides, for such a pollutant, more than 20% of the total days were unhealthy for sensitive groups. Even for ordinary people, almost 3% of the total days were shown to be very unhealthy to hazardous.