Dr. Bagley and colleagues at Michigan Technical University examined the chemical mutagenic effects of a ceramic particle trap on a medium-duty diesel engine. Diesel exhaust particles and vapor phase samples were collected from diluted (15:1) exhaust of a 10.4L displacement Caterpillar 3208 engine. The investigators compared uncontrolled (baseline) emissions with exhaust that had been modified by the use of an uncatalyzed monolithic ceramic trap. Total particulate matter, soluble organic fraction, sulfate fraction, and solid fraction were determined from dilute exhaust particles collected on 47mm Teflon-coated filters. The Ames Test was used to direct the course of chemical analyses.