CHEMICAL AND PHYSICAL CHARACTERIZATION OF AUTOMOTIVE EXHAUST PARTICULATE MATTER IN THE ATMOSPHERE (YEAR ENDING JUNE 30, 1973)

The purpose of the program is to determine the physical and chemical characteristics of exhaust particulate matter from internal combustion engines as a function of sampling procedure, engine operating conditions (including emission control systems), fuel composition, and residence time in the atmosphere. Emphasis is placed on predicting the fate of exhaust particulate matter in the atmosphere. The scope of the project work covers the generation of automobile particulate matter with specially chosen, measured engines. A major experimental study has been necessary to develop test procedures which give as true as possible values of the particulate emissions. The gaseous measurements enabled a detailed assessment of vehicle operation to be made. Electron microscope studies of the exhaust particles suggest four possible mechanisms of particle growth; agglomeration, condensation, crystal growth, deposition and ablation of exhaust system deposits.