Scientists have developed a device that produces realistic tyre wear particles in the laboratory, giving researchers a new way to investigate one of the world's fastest growing but least understood forms of pollution.
As exhaust emissions decline, attention is increasingly turning to pollution from non-exhaust sources, such as tyres. Every time a vehicle accelerates, brakes or corners, tiny fragments of tyre rubber are released into the environment. These particles are now recognised as a significant source of air, soil and water pollution, yet scientists still know relatively little about their effects on human health.
One major obstacle has been a lack of realistic laboratory models – until now. Researchers from the MacFarlane lab at the MRC Toxicology Unit, along with their collaborators, have developed TREADS – short for the Tyre Rubber Emission And Debris System – a bench-top device that recreates tyre wear under controlled conditions and generates large quantities of airborne microscopic particles similar to those produced during everyday driving.
First author of the study, Dr David O’Loughlin, explained how TREADS works: “The system generates friction against a rotating tyre sample. This mimics the wear that would occur naturally on the road. Previous studies have used tyre material that has been mechanically ground down at lower temperatures. While useful, these particles may not accurately reflect the chemistry or structure of those created on real roads, where heat and friction drive additional chemical reactions. By generating particles at temperatures of 37°C to 44°C, they more closely resemble ‘real world conditions’ and will give us a more accurate picture of what they may do to our biology.”
The need for such a tool is growing. Recent estimates suggest around 79,500 tonnes of tyre wear emissions are released in the UK each year, with roughly 4,000 tonnes entering the atmosphere. As electric vehicles become more common and exhaust emissions continue to fall, non-exhaust sources such as tyre and brake wear are expected to account for an increasingly large share of traffic-related pollution.
Researchers are particularly interested in the smallest particles called nanoparticles. As these are far smaller than the width of a human hair, they can potentially travel deep into the lungs. However, evidence on their health effects remains limited, and scientists still do not know which tyre materials or chemical components may be most harmful.
TREADS was designed to help answer those questions. Unlike particles collected from roadsides, the nanoparticles produced by the system are free from contamination by road surfaces and other environmental materials. This gives researchers a cleaner way to compare different tyre chemistries and identify the characteristics that may drive toxicity.
The researchers hope the technology will accelerate efforts to understand the health and environmental impacts of non-exhaust pollution, support the development of safer tyre materials and provide evidence to inform future regulation.
Prof Marion MacFarlane, Group Leader at the MRC Toxicology Unit and senior author of this study, shared more about the next steps for this research: “The next challenge is using TREADS to investigate what happens when realistic tyre nanoparticles interact with living cells and tissues. We hope to compare particles produced by different tyre formulations, identify which components are most harmful and determine how these particles affect the lungs and other organs. The system could also help evaluate whether new tyre designs are less toxic, providing evidence to guide both manufacturers and regulators as concerns about non-exhaust vehicle emissions continue to grow.”
“TREADS: tyre nanoparticles produced using a bench-top tyre wear simulator” was published in the journal Environmental Science Nano. Read the full publication here.