260 Characterisation of emission and exposure to diesel engine exhaust from trackless mobile machinery in underground South African platinum mines

Abstract

Abstract Background Mining remains one of the major economic drivers in South Africa, and there is a continued focus on long-term investments in mechanisation. The use of diesel-powered machines in mechanised mining has introduced a new risk among the mine workers in underground confined spaces. Evidence has shown a correlation between diesel exhaust engine (DEE) exposure and respiratory outcomes in mine workers. Recent mining research has shifted to focus on integrated control strategies/solutions to prevent exposure to DEE exposure. Objective The overarching aim of the research project was to determine characteristics of diesel engine exhaust emission at the source (aerodynamic size fractions) and to evaluate how interventions will impact the levels of DEE at the source and the workplace. Methods The study approach was a quantitative quasi-experimental designed study with an intervention component conducted in underground South African mines. DEE was measured at the source on the trackless mobile machinery (TMM) tailpipe, followed by different interventions and personal exposure measurements of diesel particulate matter (DPM) using EC as a surrogate measure for DPM and pollutant dispersion. Results The median particle number concentration significantly decreased post the interventions; an efficacy of 90-96% and 20-40% (p-value=0.001) was achieved for the machines that underwent maintenance plus installation of the DPF and machines that underwent maintenance only, respectively. Most particles emitted were between ≥0.01<0.1µm and ≥0.1<1µm. Conclusion A combination of control strategies (maintenance, retrofitting of machines with DPF, and ventilation) have shown great potential to reduce DEE in underground mines. Focus on implementing integrated strategies in preventing and reducing exposure to DEE is required.