This report presents results from a collaborative study conducted by Michigan Technological University (MTU) and the U.S. Department of the Interior, Bureau of Mines (Bureau). The objective was to assess the effects a catalyzed diesel particle filter (CDPF) and low sulfur fuel have on emissions. Emphasis was placed on determining the chemical and biological character of diesel particulate matter (DPM) from a diesel engine used in underground mining.A Caterpillar 3304, pre-chamber, naturally aspirated, 84 hp engine was tested with and without a precious metal CDPF of the “quad” design. Samples were collected during transient and steady-state engine operation for carbon monoxide (CO), oxidies of nitrogen (NOx), flame ionization detectable hydrocarbons (HC), DPM, and XAD-2 resin organic component (XOC). DPM and XOC samples were Soxhlet extracted and analyzed for mutagenicity using the Ames assay and for selected polycyclic aromatic hydrocarbons (PAHs) using high pressure liquid chromatography (HPLC).The CDPF and low sulfur fuel significantly reduced the emissions of DPM, including the soluble organic fraction (SOF), by 90 and 99 percent. Gaseous HC, CO, and XOC were also reduced by 59, 79, and 82 percent, respectively. A significant reduction of 98 percent was observed in the DPM-associated mutagenic concentration. The CDPF significantly reduced DPM-associated polycyclic aromatic hydrocarbons (PAHs), with 98 percent or greater reductions in all concentrations. Only two PAHs, fluoranthene and pyrene, were detected in any of the vapor phase samples without the CDPF and with the CDPF in place concentrations were reduced by 90 percent.These results suggest that the use of a CDPF on underground mine vehicles should prove effective in lowering DPM concentrations without significant adverse affects on other exhaust pollutants.