Plume characterization of a typical South African braai

Abstract

To braai is part of the South African heritage that transcends ethnic barriers and socio-economic groups. In this paper, a comprehensive analysis of atmospheric gaseous and aerosol species within a plume originating from a typical South African braai is presented. Braai experiments were conducted at Welgegund - a comprehensively equipped regional background atmospheric air quality and climate change monitoring station. Five distinct phases were identified during the braai. Sulphur dioxide (SO2), nitrogen oxides (NOx) and carbon monoxide (CO) increased significantly, while ozone (O3) did not increase notably. Aromatic and alkane volatile organic compounds were determined, with benzene exceeding the 2015 South African one-year ambient air quality limit. A comparison of atmospheric PM10 (particulate matter of an aerodynamic diameter <10μm) concentrations with the 24-hour ambient limit indicated that PM10 is problematic during the meat grilling phase. From a climatic point of view, relatively high single scattering albedo (ωo) indicated a cooling aerosol direct effect, while periods with lower ωocoincided with peak black carbon (BC) emissions. The highest trace metal concentrations were associated with species typically present in ash. The lead (Pb) concentration was higher than the annual ambient air quality limit. Sulphate (SO42--), calcium (Ca2+) and magnesium (Mg2+) were the dominant water-soluble species present in the aerosols. The largest number of organic aerosol compounds was in the PM25-1 fraction, which also had the highest semi-quantified concentration. The results indicated that a recreational braai does not pose significant health risks. However, the longer exposure periods that are experienced by occupational vendors, will significantly increase health risks