Two Diesel particulate matter emission control devices; the continuously regenerating trap (CRT(TM)) and the catalyzed continuously regenerating trap (CCRT(TM)) were evaluated using a mobile emissions laboratory. The source of emissions was the lab's engine that was fueled with 15 ppm sulfur fuel, and specially formulated, low sulfur (1300 ppm) lubrication oil. The objective was to characterize performance using real-time aerosol instrumentation, real-world dilution, and on-road driving conditions. The devices when combined with low S fuel and lube oil effectively removed Diesel particulate matter. The CRT produced large quantities of nuclei mode particles, the quantity of which increased as a function of exhaust temperature. The CCRT reduced the exhaust particle number concentration to levels not detectable above background storage sites, thus eliminating precursors that form nuclei mode particles. Use of low S fuel and lubrication oil prolongs the storage process. Over time it is expected that this material would be released. (C) 2005 Elsevier Ltd. All rights reserved.