The particulate matter emitted from present-day cars is a complex mixture of inorganic salts, soot and carbona-ceous material. Measurement and characterization of such particles require elaborate sampling systems and so-phisticated analytical techniques. This paper is a review of the major contributions in this area. A number of sys-tems suitable for sampling and characterization of the ex-haust particles are described. Also included is a wide se-lection of data from a number of workers that, in the au-thor’s opinion, best represent the state of the art.

Although the subject of vehicleemissions has received much attention during the past 15 years, there is little in-formation on the mechanism of particle formation during engine combustion and on the character of the particles in vehicle exhaust. The main reason for this lack of information is the complexity of the physical and chemical reac-tions that govern particle formation and their subsequent deposition and regeneration in the exhaust system of cars. Consequently, in this area, a coherent theory can follow only in the wake of experiments, and development of proper sampling procedures and analytical techniques for characterization of exhaust particles is of great impor-tance. Individual improvementsin the techniques, no matter how small, can play a significant role in improving our understanding of the phenomenon of particulate emissions from cars.