15. Diesel Engine Exhaust Emissions

The direct release of exhaust gas components from combustion processes into the environment, i.e. emission, is the primary and most important process in the chain of emission, transmission, pollutant input and impact. Naturally, a basic distinction is made between emissions from vegetation, oceans, volcanic activity or biomass decomposition for instance and anthropogenic emissions, i.e. emissions caused or influenced by humans, from power generation, traffic, industry, households and farming for instance. The following deals exclusively with anthropogenic emissions from diesel engine combustion processes. Figure 15.1 depicts the functional chain with the major anthropogenic sources [15-1]. Exhaust gas components may be harmful or harmless as well as gaseous, liquid or solid.