An investigation was carried out at a US underground mine to characterise diesel aerosols and to asses the effects of various control technologies on the concentrations and properties of particulate matter and gases emitted by heavy-duty diesel-powered equipment. This study was dedicated to evaluating the impact on mine air quality of contemporary diesel particulate filter (DPF) systems installed on mining equipment. Additional efforts were made to assess the effect of blended biodiesel fuels, yellow grease and soy, ultra-low sulfur fuel, a fuel emulsion and of selected diesel oxidation catalysts on air quality and emissions. The carbon analysis performed on the collected samples showed that the tested DPF systems reduced the mass concentrations of elemental carbon in mine air by between 70 per cent and 92 per cent. In addition, TEOM measurements, collected during these tests, showed that the total diesel particulate matter concentration in the mine air was reduced by greater than 65 per cent when DPF systems were used. The tested biodiesel blends were found to reduce elemental carbon concentrations in the mine air by between 49 per cent and 33 per cent, for the B20 (20 per cent biodiesel/80 per cent #2 diesel) of soy and yellow grease respectively and between 66 per cent and 56 per cent for the B50 (50 per cent biodiesel/50 per cent #2 diesel) of soy and yellow grease, respectively. The water-in-diesel fuel emulsion was shown to reduce elemental carbon concentrations by as much as 85 per cent. NO2 measurements showed an increase in the maximum concentrations of NO2 when catalysed DPF systems were used instead of mufflers.