EGR – filter-based purity.
In EGR technology, a proportion of the engine exhaust emissions is mixed with fresh air drawn in separately, reducing the speed of engine combustion and the temperatures generated. This technology largely eliminates the accumulation of nitrogen oxides. Soot thresholds, however, can be met only with the aid of a particulate filter (DPF). The advantage of EGR is that no second tank or additional resources are required.
*DPF is an abbreviation for diesel particulate filter. These filters are designed to reduce exhaust particles, but are more complex than catalytic converters. This is because one function of the particulate filter is to routinely recombust accumulated soot (regeneration), something which requires additional technology.