For definition of Groups, see Preamble Evaluation . Internal combustion engines have been used in cars, trucks, locomotives and other motorized machinery for about 100 years.
Engine exhausts contain thousands of gaseous and particulate substances.
Submicron-size particles are present in the exhaust emissions of internal combustion engines. The particles present in diesel engine exhaust are composed mainly of elemental carbon, adsorbed organic material and traces of metallic compounds. The composition and quantity of the emissions from an engine depend mainly on the type and condition of the engine, fuel composition and additives, operating conditions and emission control devices. Particles emitted from engines operating with gasoline are different from diesel engine exhaust particles in terms of their size distribution and surface properties. Lead and halogenated compounds are also typically found in emissions from engines using leaded gasoline.