Benefit/risk assessment of diesel particle filters (DPFs)


No diesel engine without a high quality filter” is our credo since the successful introduction of filter technology in construction machinery used to build the NEAT. NEAT railway tunnels are in operation now and construction machinery which was retrofitted with particle filters is used elsewhere. This first application of filter technology in Switzerland was a tremendous success. DPFs are widely used in tunnel construction sites since 1998, 10 years earlier than for road vehicles.

Our lab and partners established procedures to test particle filters and described them in a norm (SN 277206). Filters that are approved by the BAFU and in conformity with the Swiss clean air act should have a filtration efficiency >97% for 20-300 nm particles both, in new and aged filters (2000 operating hours). Approved filters shell not form toxic secondary pollutants such as genotoxic polycyclic aromatic hydrocarbons (PAHs), their nitrated forms (nitro-PAHs) and polychlorinated dibenzodioxins/furans (PCDD/Fs) nor have toxic metal emissions from catalysts, coatings and filter materials.

Since 1998 we assessed more than 50 diesel particle filters for their efficiency on genotoxic compounds and metals and has identified several filters that indeed induced a secondary formation of critical pollutants. These filters were not approved, but those that qualified for the filter list are safe and efficient. In other words, approved catalytic diesel particle filters are now best available technology at construction sites and many other off- and on-road applications.

In case you want to filter your exhausts, Empa can help you to assess benefits and risks of potential filters in an early stage of product development.