Source Apportionment of PM_2.5 and PM_2.5-Bound Trace Elements in Pretoria, South Africa

Outdoor PM2.5 samples were collected for 34 months in Pretoria, South Africa from 18 April 2017 to 28 February 2020. The average total PM2.5 concentration was 23.2 ± 17.3 µg.m3 (0.69–139 µg.m−3), with the highest mean recorded during winter and the lowest during summer (p < 0.05). The sources were determined by means of cross referencing the US EPA PMF 5.0 program and the NOAA HYsplit model. The sources of the total PM2.5 were mining (33%), resuspended dust (24%), industry (15%), general exhaust (12%), vehicular emissions (12%) and biomass burning (4%). Sources of air pollutants are both ubiquitous and seasonal. In central Pretoria, the largest contributing sources of PM2.5 are resuspended dust matrix and mining from surrounding areas; A winter analysis was run where As, Se and Pb was included in the dataset, confirming biomass burning sources which were typically higher during the winter season; and Air quality management policies should address both ubiquitous and seasonal sources.