The impact of hydrocarbon emissions on regional air quality in a South African metropolitan area

Abstract

The understanding of the source, transport, fate and impact of anthropogenic emissions is critical if the management of air pollution is to be effective in improving and sustaining acceptable air quality in a given area. In an attempt to improve the current lack of information pertaining to volatile organic compounds (VOC) and specifically benzene, toluene, xylene and ethyl benzene (BTEX), a study was conducted in the metropolitan area of Sasolburg, an industrial town approximately 70 kilometres south of Johannesburg, South Africa. The study aimed to assess the ambient BTEX levels in Sasolburg, comparing results with the Mpumalanga Highveld area and a non-industrial city, Potchefstroom. A number of chromatographic systems, including in situ analyses utilising an Organic Real-time Airborne Chromatograph (ORAC), passive samplers and stainless steel canisters were employed during the six-year study period. The ubiquitous nature of BTEX species in the Sasolburg, Potchefstroom and Mpumalanga Highveld areas is shown. The influence of meteorological conditions coupled to the characteristic of the pollution sources has been highlighted. The similarities in ambient levels observed in the study area and the United Kingdom have been shown. The benzene-health impact study undertaken in the Sasolburg and Potchefstroom areas has highlighted the serious challenges faced by the Sasolburg area during the period 2000 to 2004. The reduction in ambient benzene levels in 2006 at all three monitoring sites, most-notably a reduction of more than 100% at Zamdela, a residential area close to the industrial centre, is shown. The subsequent reduction in community exposure due to lower ambient benzene levels, brought about by the switching of coal to natural gas as feedstock by the petrochemical industry in Sasolburg, is demonstrated by benchmarking the study-area benzene levels with similar sites internationally.