Particulate filter: rather lenient threshold before being flunked

As of 1 July 2022, diesel cars will fail the Brussels technical inspection if their exhaust gases exceed 1 million particles per cm3. This threshold appears in the draft decree allowing the integration of the particle counter (‘PN meter’) in the technical control in the capital.

This test will replace the opacity test for Brussels’ vehicles from the Euro 5b standard onward. And don’t try to trick the Brussels rule: the new test will be implemented throughout Belgium thanks to cooperation and agreement with Flanders and Wallonia, signed in March of this year. Moreover, the use of PN measurement makes Belgium a frontrunner in Europe in the fight against soot filter fraud.

Stricter control

The devices used to carry out these tests have been on the test bench for four years. On the screen of these PN meters, the level of particles in a well-maintained vehicle usually is close to zero. However, the study shows that it reaches a maximum of 50 000 particles per cm3 for 80% of Euro 5 diesel vehicles or higher.

A recent test showed that Euro 4 diesel vehicles (without filters) emit between 5 and 10 million particles per cm3, or even more, while more recent engines have a ceiling of 1 000.

Tackling fraudsters

Therefore, the first year of testing will calibrate its tolerance level at 250 000 particles per cm3 of sputtered smoke. A lenient threshold, seen as an awareness-raising measure. The inspectors will issue an alert when this threshold is exceeded. This still does not require any repairs. Above 1 million, the vehicle will receive a red inspection certificate.

According to Paul Lecoq, technical control expert at Brussels Mobility, the targets of this new control will essentially be the fraudsters who tacitly remove their filters, as he said in L’Avenir. A vehicle with a removed filter emits around 7 or 8 million per cm3.

There will be no change in the inspection cost: the price will remain between 35 and 45 euros depending on the vehicle. The test will also take less time and be less strainful for the engines, subjected to 30 seconds of idling.

Extremely polluting

At present, the only test for quantifying diesel pollutant emissions was the opacity test. But this device is obsolete. Moreover, it does not allow for the detection of faulty particle filters. Or worse: they have been deliberately removed to make the car more ‘responsive’ or save on maintenance.

Modern diesel vehicles are designed for long-distance driving. Without those highway miles, as is the case with owners who drive them mainly in the city, the filter clogs up and hampers the engine. Owners, therefore, prefer to remove it. Moreover, it is cheaper than maintenance or replacement.

Indeed, the cost of a new filter can range from 500 to 3 000 euros. But it is a fraud with calamitous health costs: a diesel without a filter pollutes as much as… 480 cars. This is the case for 6% of vehicles. And such practices were partly responsible for the lousy name diesel cars got and the ban on (more and more) of them in low-emission zones.

7 600 premature deaths

The particle filter that has been gradually introduced in Europe over the last ten years has drastically reduced micro-emissions. Nevertheless, according to the World Health Organization, these fine particles PM10 and PM2,5, and black carbon cause 7 600 premature deaths each year in Belgium. Including 627 in Brussels, according to the Minister for the Environment, Alain Maron (Ecolo).

“That is why it is essential to check regularly that particle filters are working properly,” warns Brussels Minister for Mobility and Road Safety, Elke Van den Brandt (Groen). “These tests are excellent news for the lungs of the people of Brussels and Belgium.”