Potentials of PN-reduction of passenger cars with DPF and GPF

Particle number concentration (PN) in exhaust gas from vehicles and in the ambient air describes the ultrafine particles (UFP) below 500nm, which are recognized and legally limited in several countries as a toxic and carcinogenic pollution component.
The exhaust gas filtration is increasingly applied worldwide to reduce significantly this pollution, both on Diesel- (DPF) and on gasoline- (GPF) engines.
In the present paper further results and comparison of PN-emissions of different cars are represented.
As a bench-mark an OEM Diesel car with DPF is considered. The PN-emissions of this car are compared with CNG car without filtration and with gasoline cars equipped with GPF.
It can be concluded that the presently used GPF’s still have some potentials of improvements of their filtration efficiency and a modern CNG car would still have remarkable possibilities of PN-emissions reduction with a right-quality GPF.