Diesel: one in seven particle filters is not working
According to measurements carried out by researchers of the Catholic University of Louvain, 15% of diesel cars equipped with particle filters are seriously defective.
Because testing stations (Goca) cannot check these defects, this has a major impact on Euro 5 and Euro 6 diesel vehicles’ environmental performance.
Up to 10 000 times more particles
The study carried out on more than 750 cars in Belgium now shows that while the ‘good’ filters work very well, about 15% of the cars have a problem or simply no filter at all.
“As a result, these cars emit up to 10 000 times more particles than they should,” explains Francesco Contino, professor of thermodynamics at the University.
At low engine speeds, the observed emissions of particles larger than 23 nanometers are, on average, 5,6 times higher for Euro 5a, 2,5 times higher for Euro 5b, and 5,5 times higher for Euro 6 compared to what is mentioned in the HBEFA (Handbook emission factors for road transport).
With its particle filter not working or completely removed, one diesel car can pollute as much as 10 000 comparable diesel cars with a good working system.
DPF service is costly
These figures come as no surprise because the maintenance of such filters is quite expensive. Cleaning a filter costs hundreds of euros, and to replace a filter, you even pay 1 500 to 3 000 euros. That’s why filters (and EGR systems) are often removed.
Because the measuring method at the technical inspection is hopelessly outdated, even cars without a filter often pass the inspection. “On average, the particles emitted by the entire diesel fleet are underestimated by a factor five,” Contino adds.
New test devices as of 2022
Mobility organization VAB has already raised this issue before. “It is not very smart or effective to ban cars in Low-Emission Zones while it is not possible to monitor the environmental performance of the cars you allow,” says Maarten Matiënko, spokesman for VAB.
According to the spokesperson for the Walloon Minister of Road Safety, Valérie De Bue (MR), new, more accurate measuring devices should be installed in the inspection centers as of 2021.
These should be operational in all regions from 1 January 2022. Whether this also applies to Flanders is unclear for the moment. Similar devices have been tested lately, but the results were not conclusive yet. “Flanders cannot stay behind in this respect,” Matiënko concludes.
The Flemish Mobility Minister, Lydia Peeters (Open Vld), wants to put everything on hold concerning inspection on this subject in the test centers until Europe is ready with its legislation. She has been largely criticized for this ‘seeking for delays.’