A critical evaluation of health risk assessments of pm2.5 from coal-fired power stations

Abstract: South Africa’s coal-fired power stations release large quantities of nitrogen oxides (NOx) and sulphur dioxide (SO2) which form inhalable secondary particulate matter with an aerodynamic diameter of less than 2.5 mm (PM2.5). PM2.5 is harmful to health and has been associated with premature mortalities due to lung infections, cardiovascular disease, strokes and cancer. Health risk assessments on exposure to PM2.5 from coal-fired power stations have significantly different results in terms of health outcomes. The purpose of this research is to improve the approaches used in health risk assessment of PM2.5 from coal-fired power stations. The study area is the South African plateau encompassing the coal-fired power stations and surrounding populations in Mpumalanga, northern Free State, Gauteng, eastern North-West Province and Limpopo. A proportional log-linear approach is introduced to calculate the number of premature mortalities due to one component of total ambient particulate matter, using a log-linear RR model and ascribing premature mortalities based on the proportion of ambient particulate matter contributed by the single component of interest. The proportional log-linear approach is intended to be used to estimate premature deaths when the single source contributes PM2.5 concentrations below a relative risk model’s counterfactual exposure value. Use of a conventional relative risk model is not appropriate, since summing up premature deaths linked to all individual sources overestimates premature deaths because the relationship between relative risk and PM2.5 exposure is not linear...M.Sc. (Geography