Modelling PM10 aerosol data from the Qalabotjha low-smoke fuels macro-scale experiment in South Africa

D-grade (i.e. poor quality) coal is widely used for household cooking and h eating purposes by lower-income urban communities in South Africa. The smok e from the combustion of coal has had a severe impact on the health of soci ety in the townships and cities. To alleviate this escalating problem, the Department of Minerals and Energy of South Africa evaluated low-smoke fuels as an alternative source of energy. The technical and social implications of such fuels were investigated in the course of the Qalabotjha Low-Smoke F uels Macro-Scale Experiment. Three low-smoke fuels (Chartech, African Fine Carbon [AFC], and Flame Africa) were tested in Qalabotjha during the winter of 1997. This paper examines diurnal variations of PM10 (particles with ae rodynamic diameters less than 10 mu m) concentrations at the clinic site in Qalabotjha. Both the fuel type and the wind were found to have an effect o n the air particulate concentrations. This paper demonstrates how continuou s PM10 data together with wind measurements can be modelled. Pronounced dua l-peak diurnal variations of PM10 concentrations were found in winter's sta ble atmosphere with 30-min PM10 levels often exceeding 1000 mu g/m(3) aroun d 07:00-08:00 h in the morning and around 18:00 h in the evening. PM10 diur nal variations coincided with surface radiation inversions and residential cooking activity, suggesting that human exposure is confined to a very loca lized environment. On windy days, very low PM10 concentrations with very li ttle to no diurnal variations were found. Much of the locally generated coo king emissions may have been diluted by dispersion and transport. An expone ntial model that allowed for all measured particulate concentrations to be re-calculated to 'zero wind' values was created to estimate the impact of D -grade coal combustion. From analysis of variance (ANOVA) calculations on t he 'zero wind' concentrations, it is concluded that the combustion of low-s moke fuels would make a significant improvement to the air quality in Qalab otjha. (C) 2000 Elsevier Science B.V. All rights reserved.