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Air pollution from vehicles is a subject of major concern for public health and the environment. Since the beginning of the 20th century, attention has rather focused on toxic emissions from combustion engines. From the 1970s, stricter environmental regulations emerged in many countries (Europe and the United States in particular). The 1980s marked the beginning of the emergence of more advanced automotive emissions control technologies. The culmination of this widespread awareness was surely the diesel gate in 2009.
From the 2020s, another awareness is taking place: that of the pollution produced by car brakes. As ADEME titled it in this article: “ More than half of the fine particles emitted by recent road vehicles no longer come from the&# 8217;exhaust “. The particles emitted during braking would therefore be a new enemy of the environment. A new study published on March 11 in the journal Proceedings of the National Academy of Sciences adds grist to the mill.
The electric charge of particles: a surprising discovery
The study was led by Adam Thomas, doctoral student under the direction of Jim Smith, professor of chemistry, and Paulus Bauer, postdoctoral researcher at the University of California at Irvine. This research has highlighted a still unknown aspect of these particles resulting from braking: 80% of these are electrically charged.
When the brake pads press against the disc to slow the vehicle, this friction process emits particles and heat. What we didn't know, however, is that this friction process can ionize the particles, that is i.e. give them an electric charge.
An interesting property, which could be exploited in order to reduce the pollution caused by these particles. It would eventually be possible to use devices like electrostatic precipitators, which generate an electric field to capture charged particles. This would prevent them from dispersing and harming human health or the environment.
Health and environmental consequences
Currently, research into the toxicity of these particles is only at a preliminary stage. Manabu Shiraiwa, professor of aerosol chemistry at the University of California, Irvine, explains: “The toxicity and health impact of particulate matter braking are largely unknown […] Recent research from my laboratory indicates that they may induce oxidative stress, but further research are necessary “.
Oxidative stress, according to Futura Sciences « corresponds to an attack on cells by radicals free » and can cause cellular damage and contribute to various diseases.
Another aspect of concern: role of electric cars in this pollution. Although they do not produce emissions when operating, they still contribute to emit particles when braking. Although they have a regenerative braking system that relieves the brake discs and pads, “they emit more particles from tire contact -road and re-suspension, due to the larger size of their tire due to their greater mass » explains ADEME.
What solutions to reduce invisible emissions ?
If it is ever proven that these particles are truly toxic, we already know that the public health risks posed by brake emissions is not evenly distributed within the population. Lower-income communities, at least in the United States, are often much more exposed to heavy traffic. Already vulnerable by exhaust emissions, the penalty would be double for them.
For Barbara Finlayson-Pitts, professor emeritus of chemistry at the University of California at Irvine, characterizing these emissions is crucial. She explains: “ These areas are generally found in disadvantaged neighborhoods and highlight a crucial aspect of environmental justice that has often been ignored ”. The most modest will toast more than the others, nothing new under the sun, unfortunately.
The team in charge of this research has gone outside the walls of the laboratories to s’engage directly with populationsliving in these sensitive areas. A partnership was established with the Madison Park Neighborhood Association in Santa Ana, California to raise awareness and educate the public about the dangers of brake particles. A resolutely social approach, which will perhaps one day help people to campaign to demand changes in public policies if necessary.
For the moment, there is no miracle solution, and research must continue. Accelerate to better understand the health challenge represented by these particles. This facet of automobile pollution must no longer be ignored, and having more precise data is necessary to take action.
- A new American study has highlighted that 80% of particles emitted by car braking are electrically charged.
- A property that could work in our favor in possibly making it possible to capture these particles using specific devices before their emission.
- For the moment, we lack data to really understand the ecological and health impact of these particles.
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