In the framework of the urban air pollutionWe usually think of exhaust pipes, industrial chimneys, and major traffic jams. However, a silent and lesser-known source is gaining prominence: the microplastics in everyday life that come off the wear and tear of the tires every time a car drives through the city.
These tiny fragments of synthetic rubber, mixed with other chemical compounds, They don't just stay on the asphaltA significant portion ends up suspended in the atmosphere, settles on urban vegetation, and eventually enters the lungs of those who live and travel near high-traffic roads, with implications that European science is beginning to measure more precisely.
From the wheel to the air: how tire microplastics are generated
Every time a vehicle moves forward, the constant friction between the tire and the pavement causes microscopic cracks on the tire surfaceThese micro-cracks result in a continuous shedding of small particles of rubber, additives, carbon black, and remnants of other materials that are part of the wheel compound.
Far from being a simple, ineffective black powder, these particles are known as tire wear particles A significant portion of these particles fall into the PM10 range and, in some cases, even finer particles. This size allows them to remain airborne long enough to disperse throughout entire neighborhoods, penetrate residential streets, and accumulate in areas far from the main roadway.
The amount of microplastics released depends on factors such as the vehicle weight, speed, type of asphalt, and driving style. Driving style This has a direct impact: heavier vehicles and aggressive driving (frequent acceleration and braking) significantly increase abrasion. Added to this is brake wear, which contributes additional particles rich in metals and resins, further contributing to the overall pollution load not originating from the exhaust.
While traditional regulations have reduced combustion gases, emissions from tire and brake friction have remained virtually unchanged for decades. outside the regulatory radarThe result is that, as traditional pollutants decrease, the relative weight of these solid particles in the urban air mixture increases.
A veil of microplastics over urban vegetation
The particles emitted by the friction of the wheels do not just remain suspended. Over time, They end up being deposited on multiple urban surfacesfrom facades and floors to, especially, the leaves of trees and shrubs that line streets, parks and avenues.
Studies using lichens and vegetation as bioindicators have confirmed high concentrations of compounds associated with tires near European motorways and major ring roads. Particle density decreases with increasing distance from the road, but residues are still detected in more distant residential areas, demonstrating its dispersive capacity.
When these microplastics accumulate on leaves, they can create a thin film that It interferes with photosynthesis, gas exchange, and transpiration.In the long term, this layer can affect the growth of urban plants, which are already subject to stress from heat, soil compaction, and water scarcity. Furthermore, when trapped in the vegetation, the particles become... form part of the base of the urban food chain, with the potential to scale up to other organisms.
Rain and wind redistribute this material. Some of it is washed into the sewer system, then slides into... rivers, soils and bodies of waterwhere microplastics from tires add to other sources of plastic pollution. Another fraction becomes airborne again, feeding back into the air-soil-water exposure cycle.
Air pollution: a dominant and poorly regulated source
Research conducted in different countries points in the same direction: the Tire wear has become established as one of the main sources of microplastics in urban air, to the point of exceeding in many cases the direct emissions of combustion engines.
Air quality analyses in cities with high traffic density have found chemical compounds characteristic of tire rubber in almost all of the samplesInternational studies mention detection rates exceeding 90%, suggesting that these particles are a regular part of the cocktail we breathe in large metropolitan environments.
Urban models developed for densely populated areas of Europe estimate that tons of particles are released annually originating from the daily use of cars, trucks, buses, and motorcycles. Although the exact distribution varies between cities, the general trend confirms that the problem is not isolated, but structural, linked to traffic volume and the current design of mobility. To move towards solutions, the sustainable mobility It is presented as a key alternative.
Furthermore, the transition to electric vehicles is not without its nuances. These cars eliminate local exhaust emissions, but their The increased weight due to the batteries increases the force of friction on the pavement. Without parallel innovations in stronger and lighter tire compounds, some studies project that abrasion could even increase in the future if no action is taken at the source. In this context, the choice of cars that pollute less and complementary technologies will be important.
Health risks: from the street to the lungs
The scientific community's concern focuses on both the quantity and size of these particles. Many fragments derived from tire abrasion fall within the fractions PM10 and PM2,5which means they are small enough to penetrate deep into the respiratory system.
Continued exposure to this type of pollution is linked to a increase in respiratory and cardiovascular diseasesUltrafine particles can reach the deepest parts of the lungs and, in some cases, enter the bloodstream, promoting systemic inflammatory processes. Higher rates of asthma and chronic respiratory problems have been observed in areas near roads with heavy traffic, especially among children and the elderly.
In addition to the physical dimension, there is also the chemical one. Microplastics from tires incorporate additives, organic compounds and heavy metals that are released over time. This cocktail of potentially toxic substances adds further layers of risk that are still being investigated, but which reinforce the need to treat this pollution with the same seriousness as other classic air pollutants.
From an environmental point of view, the persistence of these materials poses a scenario of cumulative pollutionOnce released, microplastics do not degrade easily and remain for long periods in air, soil and water, making any short-term natural removal strategy difficult.
Europe makes its move: regulation, innovation and changing habits
Until recently, most regulations focused almost exclusively on the exhaust pipe. However, scientific evidence has prompted the European Union to include emissions not from exhaust within their regulatory frameworks. The upcoming Euro 7 standard incorporates, for the first time, specific limits for particles generated by brakes and tires, which will require manufacturers and suppliers to improve designs and materials.
The industry is already working on more durable and less abrasive rubber compoundsas well as in braking systems that reduce particle emissions. However, these technological advances need to be accompanied by a rethinking of urban mobility: more public transport, increased active mobility (cycling, walking), and an effective reduction in the number of private vehicles on the road, especially in urban centers.
Alongside the structural changes, specialists recommend a series of everyday measures To mitigate the problem, keeping tires in good condition and properly inflated, avoiding overloading the vehicle, and adopting a smooth driving style—with gradual acceleration and less abrupt braking—reduces abrasion and, therefore, the generation of microplastics.
For people who travel on foot or by bicycle in busy areas, experts point out some self-protection guidelines: whenever possible, choose routes somewhat away from the main avenues, drive on secondary streets and, at times of peak pollution or direct proximity to traffic, consider using FFP2 filtering masks as an additional barrier against fine particles.
All this body of evidence paints a picture in which the Microplastics from tires have become a key component of urban air pollutionwith impacts ranging from human health to flora and ecosystems. Addressing this challenge requires recognizing it as a top priority, promoting regulations that go beyond the exhaust pipe, investing in materials innovation, and, above all, rethinking how we move around the city to reduce our dependence on cars and thus alleviate this source of pollution, as discreet as it is persistent.
