Imperial report warns of tyre wear particulates

Six million tonnes of tyre wear particles are released globally each year. In London alone, 2.6 million vehicles emit around nine thousand tonnes of tyre wear particles annually. In a new briefing paper, a multidisciplinary group of Imperial experts including engineers, ecologists, medics, and air quality analysts have called for as much investment into tyre wear research as there is for reducing fuel emissions, as well as for understanding the interactions between emissions and tyre wear.

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“Tyre wear particles pollute the environment, the air we breathe, the water run-off from roads and has compounding effects on waterways and agriculture,” said lead author Dr Zhengchu Tan, from Imperial’s Department of Mechanical Engineering. “Even if all our vehicles eventually become powered by electricity instead of fossil fuels, we will still have harmful pollution from vehicles because of tyre wear. 

“We urge policymakers and scientists to embark on ambitious research into tyre wear pollution to fully understand and reduce their impacts on biodiversity and health, as well as research to reduce the generation of these particles.” 

In the briefing paper, the researchers discuss how tyre wear leads to these particles, where the particles end up, their potential effects on people and planet, and why we must act now. As tyres break down, they release a range of particles, from visible pieces of tyre rubber to nanoparticles. Large particles are carried from the road by rain into rivers, where they can leach toxic chemicals into the environment.

Smaller particles become airborne and can be inhaled, tiny enough to reach into the deep lung. These particles may contain a range of toxic chemicals including polyaromatic hydrocarbons, benzothiazoles, isoprene, and heavy metals like zinc and lead. While existing technological interventions - such as filters -  and environmental policies could help to control our ecological footprint, the Imperial team says there are huge gaps in our knowledge, understanding, and ability to forecast the impacts of tyre wear pollution.

“We are growing increasingly concerned by the impact of tyre wear on human health,” said co-author Professor Terry Tetley, from Imperial’s National Heart and Lung Institute.

“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.” 

According to the Imperial paper, research efforts to address the problems associated with tyre wear should include:

• Establishing standardised ways of measuring environmental tyre 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 tyre materials
• Launching new trials to better understand the short and long-term effects of different 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 tyre materials pass wear resistance regulations