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Portable Emissions Measurement Systems (PEMS) represent a robust and accurate solution to study the in-use emissions of combustion engines and are becoming part of the emissions control regulations, as evidenced by the latest requirements introduced in the United States. Their application is ranging from large heavy duty engines to small light-duty vehicles and off-road mobile machinery. Currently, PEMS for gaseous exhaust measurements exhibit performances that are close to the ones of laboratory grade systems, but the development of portable PM instruments remain a complex challenge, as simultaneous progress take place in engine and after-treatment technologies. This paper presents the PM phase of the European PEMS program, aiming at checking the feasibility of PEMS to measure accurately particle mass at low PM levels.

The health threat from sub-100 nm particulates, emitted in significant numbers from gasoline vehicles, and anticipated changes in legislation to address this, have prompted investigation of techniques capable of trapping and oxidizing particulates from gasoline engines. Numerical studies have indicated that cooling to encourage particle capture by thermophoresis is less effective than use of electrostatic fields. A laboratory wire-cylinder electrostatic trap is under development, showing promising initial results. As an alternative trapping technique, the effectiveness of a cordierite wall-flow filter has been demonstrated, in simulation experiments and on a GDI-engined vehicle. Catalysts have been identified for particulate oxidation at typical exhaust temperatures, using water vapour and carbon dioxide as the oxygen source and retaining activity after short-term high-temperature aging.