PM10 monitoring and receptor modeling in some urban areas of South Africa

Several source apportionment studies have been conducted in some of the urban areas of South Africa following US EPA guidelines. These studies involved the measuring of close to 40 new source profiles, ambient air sampling, chemical analyses and the CMB7 source apportionment modeling of PM10 size fractions. Source and ambient data were collected by Mintek over a five year period at sites in Vereeniging, Vanderbijlpark and Sasolburg (all in the Vaal Triangle), Olifantsfontein, Nelspruit and Randburg. Comparison of the gravimetric data show definite seasonal trends, with the highest levels being recorded during the winter months at sampling sites close to townships which use domestic coal as their prime source of energy. In the industrial areas of the Vaal Triangle and Olifantsfontein the pollution levels are at their highest, with the US EPA 24-hour national ambient air quality standard of 150g per cubic meter being exceeded on several occasions. The US EPA annual mean standard of 50g per cubic meter was also exceeded at these sites. The lowest PM10 levels were recorded in the residential areas Randburg and Nelspruit (Valencia Park). The source apportionment results show domestic coal combustion, fugitive soil dust, secondary salts of ammonium sulfate and nitrate, and power plant fly-ash to be major contributors to airborne particulate pollution. For the Nelspruit sites biomass burning is a major contributor. Minor sources include iron arc furnace, sinter plant and coking furnace dusts. Petrol vehicle emissions are also a minor source of PM10 pollution. Results from these studies emphasize the need for a continuous national air monitoring network for South Africa, from which the authorities, industry, the public and the environment can benefit