Diesel engines emit a mixture of gases and particulates derived from the combustion of diesel fuel. This variable mix is called diesel engine exhaust (DEE).

The composition of DEE varies greatly and depends on several factors, for example the composition of the fuel, characteristics of the diesel engine, the load of the engine, and the type of lubricating oil.

DEE and particulate matter (PM) are often lumped together, but the particulate components from DEE however usually only are part of particulate matter.

DME en fijnstof worden vaak over één kam geschoren, terwijl de deeltjesvormige componenten uit DME doorgaans slechts onderdeel van fijnstof zijn.