The famous Diesel-Gate of the Volkswagen group which broke out almost 10 years ago hung the diesel on the list of enemies to shoot down. Completely discredited by this case, the automotive industry then turned its fight against automotive pollution by focusing on vehicle emissionsthat is to say what comes out of their exhaust pots, and nothing else. But it was actually a tree that hid a gigantic forest.
A new study published on February 13 in the journal Toxicology party and fiber has just pointed another danger, largely underestimated: Brake pad dust.
The hidden side of road emissions
The air we breathe daily kills seven million people in the world every year, swept away by air pollution. Fine particles (PM2.5), nitrogen oxide (Nox) or Ozone (O3), It’s a poisoned cocktail Who enters our lungs every day, even more when we live in urban areas.
However, this impressive figure is not simply due to the scrolls of smoke escaping from combustion engines. A phenomenon, long remained in the shadows, plays a preponderant role in this macabre sum. That of so -called ” non-escape ». What is it exactly?
These are dust from the mechanical stresses suffered by a vehicle as soon as it is in motion: incessant friction between the tires and the asphalt, the wear of the brake pads, and the continuous erosion of the roads. If awareness around this type of pollution has accelerated from the 2010s, The reality highlighted by this new study is very disturbing.
In many European countries, these particles now exceed the traditional rejections of engines in quantity. This trend is all the more worrying since these particles are particularly fine, even ultrafine, which makes them more easily inhalable and capable of penetrating deep into the body, to pulmonary alveoli and even blood.
At each braking, each turn, each acceleration is therefore released in the air millions of invisible particles, a complex mixture of substances, including heavy metals, polycyclic aromatic hydrocarbons (HAP) and others extremely toxic compounds. Their small size allows them to stay in suspension in the air for long periods and to travel long distances, thus contaminating areas far from their place of issue.
Asbestos -free plates, but not without danger
How does the disk braking work in a car work? As soon as we press the brake pedal, two plates are sticking out a tour turning several hundred laps per minute, fixed on the wheel hub. This friction force transforms the kinetic energy of the vehicle into heat (several hundred degrees in the most extreme cases) and this friction slows the rotation of the wheel, which slows down or stops the vehicle.
It is certainly very effective, but the plates, by dint of being stressed, wear out and release these particles which we were talking about in the first part. So much for the small mechanical/technical point, very well explained in the video below (under French titles available).
https://www.youtube.com/watch?
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In 1999, the story took a turning turn with tragically ironic accents. Faced with overwhelming evidence of the dangers of asbestos, the United Kingdom has banned this brake pad material. Automobile engineers, faced with this challenge, then developed an alternative: asbestos -free organic materials, called Nao. A solution that seemed, at the time, Conjugate performance and health security.
However, researchers behind this February 13 study have reconstructed a miniature pulmonary environment, exposing living cells to dust generated by these new platelets. The results are catastrophic: not only are these NAO particles more aggressive for our pulmonary tissues than their asbestos ancestors, But they even surpass the so much decried toxicity of diesel particles.
Copper, new suspect number one
This toxicity hides a well identified chemical element: copper. Artificial intelligence techniques have made it possible to point out its massive presence in dust from Nao platelets. The researchers made a capital discovery: by neutralizing the copper present in these dust, their toxicity decreases considerably. An observation all the more alarming as almost half of the copper present in the air that we breathe comes from the wear of brakes and tires.
Breathing copper particles is absolutely deleterious for health : irritation of the respiratory tract, chemical pneumonia, chronic pulmonary lesions, even neurological attacks (certain studies having suggested a possible link between exposure to copper and neurological disorders such as Alzheimer or Parkinson’s disease).
The electric car, often presented as the miracle solution to urban pollution, does not escape this problem. Most VEs, heavier due to batteries on boardgenerate more wear particles than thermal vehicles. One aspect that even regenerative braking fails to eliminate.
Faced with this observation, Europe is preparing to act, even if a little late: the first suspicions around this source of pollution dating back to the early 2000s. New Euro 7 anti-pollution standardswhich will come into force in November 2026, will impose limits for the branch dust emissions for the first time. In the United States, California and Washington condition have already legislated to reduce the copper content of brake pads. A decision originally motivated by the protection of aquatic life, the runoff of these particles threatening marine ecosystems.
In the United Kingdom alone, these programs represent today 60 % of polluting particles from road transport. In France, The proportion is significantly the same And it is located around 59 % according to ADEME. A titanic ratio, reminding us that the time has come to consider with the same attention All sources of automotive pollutionwhether they leave the exhaust or result from the mechanical wear of vehicles.
- Particles from brake wear are now exceeding in quantity emitted the exhaust gases for automotive pollution.
- Composed of toxic substances such as copper, they prove more dangerous for health than diesel particles.
- They represent up to 60 % of polluting emissions from road transport in certain European countries, a major problem still not very supervised.
