Tire Wear a Major Source of Microplastics, Say Researchers

Imperial College London experts warn that even though EVs remove the problem of fuel emissions, society will continue to grapple with particulate matter caused by tire wear.

Stephen Moore

February 28, 2023

5 Min Read
worn car tire
BackyardProduction/iStock via Getty Images

Imperial College London experts are calling for more to be done to limit the potentially harmful impact of toxic tire particles on health and the environment. The researchers from Imperial College London’s Transition to Zero Pollution initiative warn that even though electric vehicles remove the problem of fuel emissions, particulate matter caused by tire wear will continue to be a concern.

Six million tonnes of tire wear particles are released globally each year. Particulate matter from tire wear is a significant source of microplastics in rivers and oceans, and tire wear in cities could pose up to a four-fold greater risk to the environment than other microplastics, according to the researchers. Technically speaking, though, it could be argued that identifying thermoset rubber as a type of microplastic could confuse the general public, which tends to associate microplastics with particles derived from discarded items molded from thermoplastic resins that gradually degrade, as well as pellets that escape into the environment before they are molded. The same is true for polyester, nylon, and acrylic lint, which is shed from clothing during each washing cycle and is also a major source of microparticle contamination in waterways.

Despite its prominent presence as a source of microparticulate pollution in the environment, research on the environmental and health impacts of tire wear has been neglected in comparison to fuel emissions. Imperial College researchers say that the effect of new technologies on the generation and impact of tire wear should be a priority.

Call for more resources in tire-wear research

In a new briefing paper, a multidisciplinary group from Imperial College, including engineers, ecologists, medics, and air-quality analysts, have called for as much investment into tire-wear research as there is for reducing fuel emissions — and for understanding their interactions. 

Lead author Dr Zhengchu Tan of Imperial’s Department of Mechanical Engineering said: “Tire-wear particles pollute the environment, the air we breathe, the water run-off from roads and has compounding effects on waterways and agriculture. Even if all our vehicles eventually become powered by electricity instead of fossil fuels, we will still have harmful pollution from vehicles because of tire wear. We urge policymakers and scientists to embark on ambitious research into tire-wear pollution to fully understand and reduce its impact on biodiversity and health, as well as research to reduce the generation of these particles.” 

EVs source of higher tire-particle emissions

“Electric vehicles are a crucial step forward to decarbonize transport, but we need to look at the big picture, too. Some are concerned that electric vehicles tend to be heavier, which might increase tire wear. This is exactly why Imperial College London is driving a holistic, joined-up approach to sustainability challenges,” said the authors of the study.

As tires break down, they release a range of particles, from visible pieces of tire rubber to nanoparticles.

In the briefing paper, the researchers discuss how tire wear leads to these particles, where the particles end up, their potential effects on people and the planet, and why we must act now. As tires break down, they release a range of particles, from visible pieces of tire rubber to nanoparticles. Large particles are carried from the road by rain into rivers, where they may leach toxic chemicals into the environment, whilst smaller particles become airborne and breathed in. They are small enough to reach into the deep lung. These particles may contain a range of toxic chemicals, including polyaromatic hydrocarbons, benzothiazoles, and isoprene, and heavy metals like zinc and lead. 

Co-author Dr Will Pearse from Imperial’s Department of Life Sciences said: “Tire waste does not naturally degrade and instead builds up in the environment, and may interact with other pollutants as well as biological organisms. Our gaps in understanding make further research and development of new solutions vital so we can limit all types of vehicular pollution.” 

Tire-wear particles may impact human health 

The impact of tire-wear particles on human health is an increasing cause for concern, and the full long-term effects on our health urgently require more research. 

There is emerging evidence that tire-wear particles and other particulate matter may contribute to a range of negative health impacts including heart, lung, developmental, reproductive, and cancer outcomes. 

Co-author Professor Terry Tetley of Imperial’s National Heart and Lung Institute said: “We are growing increasingly concerned by the impact of tire wear on human health. As some of these particles are so small, they can be carried in the air, it’s possible that simply walking on the pavement could expose us to this type of pollution. It is essential that we better understand the effect of these particles on our health.” 

Shifting gears to reduce tire pollution

The researchers argue that reducing tire pollution should be seen as a critical part of making transport cleaner and more sustainable, alongside reductions in CO2 and other exhaust emissions. In tackling the climate crisis, we should design better systems and technologies to protect the environment; research funding, government policy, and regulatory frameworks should reflect this. 

The report authors call for policymakers and scientists to investigate the complex problems related to tire-wear pollution, from the basics of wear-particle production to understanding how these particles affect the health of people and the planet. Potential innovative solutions include particle-capture technologies, new advanced materials, and disruptive business models that encourage different transport choices. These need to be coupled with clear policies and regulations and lead to a broader discussion around urban transport systems.

The research efforts, they say, should include the following: 

  • Establishing standardized ways of measuring environmental tire-wear levels and their toxicity; 

  • reducing harm to land and water species and in humans by tightening limits on the use of harmful components in tire materials; 

  • launching new trials to better understand the short- and long-term effects of differently sized particles on the environment and human health;

  • efforts to better understand underlying wear mechanisms and to propose wear-mitigation strategies, such as reducing vehicle weight, using advanced driving techniques, and ensuring tire materials pass wear-resistance regulations.

About the Author(s)

Stephen Moore

Stephen has been with PlasticsToday and its preceding publications Modern Plastics and Injection Molding since 1992, throughout this time based in the Asia Pacific region, including stints in Japan, Australia and his current location Singapore. His current beat focuses on automotive. Stephen is an avid folding bicycle rider, often taking is bike on overseas business trips, and proud dachshund owner.

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