Assessment of criteria pollutants contributions from coal-fired plants and domestic solid fuel combustion at the South African industrial highveld

Abstract

The World health organization (WHO) is particularly concerned about the ambient concentrations of Particulate Matter (PM10, PM2.5), Sulfur dioxide (SO2), Nitrogen dioxide (NO2), and Ozone (O3). This paper investigates the contributions of both the coal-fired plants and the coal-burning households to these critical pollutants. Using twelve months’ data, the annual concentrations of these pollutants were 60, 34, 39, 14, and 64 μg/m3 respectively with PM10, and PM2.5 exceeding the annual National Ambient Air Quality Standard (NAAQS). The diurnal pattern of PM10 and PM2.5 have double maxima corresponding to the cooking pattern of the community dwellers while O3 concentration peaks at noon which can result from photochemical reactions. Seasonally, all pollutants have their maximum concentrations during the winter except O3 that has high concentrations during the spring and summer. During the period, PM10 and PM2.5 concentrations exceeded the 24 h NAAQS for 104, 190 (55, 30%) days, and the World Health Organization (WHO) 24 h standard for 125, 225 (66, 36%) days respectively. The 8 h rolling mean of O3 also exceeded the NAAQS 490 times far above the allowable limit. The study indicates that PM10 and PM2.5 were mainly generated within the community. NO2 seems to receive significant contributions from biogenic emissions from the wetland area of the community while SO2 and O3 may be receiving significant contributions from the coal-fired plants as shown by the air mass backward trajectory modeling.