More than a decade ago a scandal known as Dieselgate shook the automotive world, and it still reverberates today. With the Volkswagen Group as the main culprit, it emerged that the nitrogen oxide (NOx) emissions from its diesel cars were being manipulated on test benches, so under real-world conditions they polluted more.
A major scientific study in Science Advances put gasoline engines under the microscope and questioned the effectiveness of particulate filters: the emissions from modern gasoline cars, despite complying with the European EURO 6e standard (the strictest to date), can become significantly more harmful once released into the atmosphere. Something that is not taken into account.
Regulating exhaust emissions is no longer enough to protect our health
The international study led by the German research center Helmholtz Munich and the University of Rostock dismantled the efficacy of particulate filters and that the filtered exhaust gases of vehicles complying with the previous Euro 6d standard are not as safe for health, according to their investigations.
The research focused on a gasoline vehicle equipped with a gasoline particulate filter, designed to drastically reduce primary particle emissions such as soot produced during combustion. The freshly emitted exhaust gases did not show detectable cytotoxic effects in human lung cells, but once they underwent photooxidative aging, they became considerably more toxic.
“Aged emissions caused substantial DNA damage and oxidative stress in both cancerous alveolar epithelial cells and normal bronchial epithelial cells. This toxicity was not only associated with freshly formed particles […] but also with oxidized volatile compounds, such as carbonyls, generated during their stay in the atmosphere”, the study details.
As Phys.org rightly pointed out, the conclusion of this important finding is that while current standards guarantee low emissions from the tailpipe, they do not account for the chemical transformations those emissions undergo once released into the environment.
In other words, the current regulation focuses on emissions measured right after combustion, and not how they behave once released. And this is a problem because filtered emissions remain toxic when exposed to sunlight.
For the study’s lead author and Helmholtz Munich researcher, Dr. Mathilde Delaval, these findings indicate a “critical” deficiency in the current testing and regulations on how air quality standards are set. The conclusion is clear: regulating exhaust emissions is no longer enough.
But this study is not alone. More recent investigations such as ResearchGate – Developments for Future EU7 Regulations point out that by including nanoparticle data between 10 and 23 nanometers in the equation (previously only particles larger than 23 nanometers were measured) emissions rise by between 17% and 40%.
The new Euro7 regulation has been approved by the European Parliament and includes measures for the ‘invisible soot’ (PN10) particles. It will start to apply by the end of 2026 with an NOx limit of 60 mg/km. A change that is going to disrupt the combustion car industry a bit more. Again.
And there’s more. From the implementation of Euro7, braking pollution will also be taken into account. Yes, because that metallic dust that sticks to your wheels and makes them look awful is pollution too, and no, it hadn’t been considered until now.
This source of pollution affects both electric and gasoline cars and is driving multi-million-dollar investments by manufacturers like Brembo to bring the emitted particulates down to between 3 mg/km and 7 mg/km. The limits are detailed in S&P Global’s report.
The concern about microparticles has a notable reach beyond laboratories, with the United Nations Economic Commission for Europe adopting new emission measurement measures to adjust health risks in cities.
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