Vehicle-related particulate matter (PM) emissions may arise from both exhaust and non-exhaust mechanisms, such as brake wear, tyre wear, and road pavement abrasion, each of which may be emitted directly and indirectly through resuspension of settled road dust. Several researchers have indicated that the proportion of PM2.5 attributable to vehicle traffic will increasingly come from non-exhaust sources. Currently, very little empirical data is available to characterise tyre and road wear particles (TRWP) in the PM2.5 fraction. As such, this study was undertaken to quantify TRWP in PM2.5 at roadside locations in urban centres including London, Tokyo and Los Angeles, where vehicle traffic is an important contributor to ambient air PM.

The sources of PM2.5 vary spatially with long-range transport sources generated mainly from secondary PM and local sources generated mainly from combustion processes associated with industrial operations and road transport. A recent literature review of various PM2.5 local source apportionment studies conducted in 51 different countries concluded that 25% of urban ambient air pollution from PM2.5 is contributed by traffic, 15% by industrial activities, 20% by domestic fuel burning, 22% from unspecified sources of human origin, and 18% from natural dust and salt. Both primary and secondary PM were accounted for in the analysis and the contribution was dependent on the source. For example, the researchers generally apportioned traffic sources by primary PM emissions and the unspecified sources of human origin based on secondary PM emissions. PM2.5 also varies spatially and temporally.

Over the last 20 years, environmental agencies worldwide have enacted regulations, including those for motor vehicles, in an effort to reduce the emissions of PM2.5; and, indeed, a decline is observable in areas with established monitoring networks. For example, in the US, from 2000 to 2016, the nationwide levels of PM2.5 have decreased 42%; with the vast majority of the measurements below the national standard of 12 μg/m3 since 2012. In Europe (EU-28), the emissions of primary PM2.5 decreased by 16% from 2003–2012.

Vehicle-related PM emissions may arise from both exhaust and non-exhaust mechanisms, such as brake wear, tyre wear, and road pavement abrasion. Several researchers have indicated that the proportion of vehicle traffic attributable to PM2.5 will come increasingly from non-exhaust sources, due to additional regulations limiting vehicle exhaust emissions. The current and future contributions of non-exhaust sources have been evaluated primarily through indirect methods such as various receptor-modelling approaches or air dispersion modelling paired with emission inventories. A recent literature review of non-exhaust emissions reported more than 250 estimates of contribution to ambient air PM.

When tyres interact with the roadway surface, tyre and road wear particles (TRWP) are produced, containing both the tread rubber and embedded road material.

The contribution of tyre wear to ambient PM10 and PM2.5 has been estimated to be between 0.8–8.5% and 1–10% by mass respectively, although the data are sparse and most estimates are indirectly calculated with only a few observational studies. Given the complex composition of the TRWP, a variety of analytical techniques have been proposed, but the only ones with sufficient specificity to the particles are chemical markers associated with the tread rubber, which include monomers styrene and 1,3-butadiene, as well as the dimers vinylcyclohexene and dipentene. Given the predicted increases in non-exhaust emission contributions to PM2.5, the current study was undertaken to measure levels of TRWP in PM2.5 in urban environments where traffic-related PM is significant. Sample locations were chosen to be representative of likely human exposure in various roadside microenvironments. To facilitate comparison to our earlier work and estimates published by others, we present mass-based concentrations and relative contribution to PM2.5 for both TRWP and tread for each sampling location.

Materials, methods

To select the cities for inclusion in this study, data were assembled for large urban areas in Europe, Asia, and the United States. A selection matrix was developed to identify cities based on several criteria including, levels of ambient PM2.5, traffic loads, population density, and local regulatory actions to reduce PM2.5.

In Europe, five cities were considered, including Barcelona, London, Milan, Paris and Rome, with London being ultimately selected. In Japan, six cities were considered, including Nagoya, Osaka, Tokyo, Saitama City, Yokohama, and Kyoto, with Tokyo being ultimately selected. In the US, three cities were considered, including Atlanta, Los Angeles and New York City, with Los Angeles ultimately selected.

Within each city, the site selection criteria included the presence of identifiable traffic and historical presence of high PM2.5 levels where possible. All air samples were collected near the roadside, and the distance from road was dictated by logistical constraints such as security of the equipment and available power sources. For London only, an urban background site was also included.

The analytical technique is based on the characteristic fragments generated by the thermal decomposition of the tyre tread polymers that include styrene butadiene rubber (SBR), butadiene rubber (BR) and natural rubber (NR). Briefly, the method consists of the following steps: the tread rubber polymers in environmental samples undergo thermal decomposition at 670 °C by Curie-point pyrolysis; next, the thermal decomposition products are separated using a gas chromatograph (GC); and finally, the pyrolysis fragments are quantified with mass spectrometry (MS).

The data were evaluated using the Analysis of Variance (ANOVA) and regression models to identify differences among the cities and trends in determinants of TRWP concentrations between sampling locations and cities.

Results

In total 80 samples were analysed, and the TRWP detection frequencies ranged from 0–100%. The lowest detection frequencies were recorded in Los Angeles, with four of the six locations showing no detections. The total ambient PM2.5 levels were low in Los Angeles during sampling days, which was surprising due to the historical levels recorded in the area for the same time of year.

The TRWP made a small contribution to total ambient PM2.5 levels, representing 0.1–0.68% of the total PM2.5 across all locations. The range of concentrations of TRWP were 0.012–0.29 μg/m3 in London, 0.010–0.1 μg/m3 in Tokyo, and 0.004–0.072 μg/m3 in Los Angeles. The highest concentrations were recorded at the Blackwall Tunnel Approach in London (mean 0.104 μg/m3 and range (0.03–0.29 μg/m3)) where significant braking activity occurs before the tunnel portal which creates more tyre wear abrasion than constant speed driving.

The highest TRWP PM2.5 concentration measured in Tokyo was at the Kawasaki Industrial Road location, which had the highest traffic count of the Tokyo sites. In both Tokyo and London, the traffic composition was dominated primarily by passenger car and light duty vehicle traffic, with truck traffic generally comprising less than 20% of the total traffic. One exception was Kawaskai Industrial Road, where the truck traffic accounted for nearly 43% of the traffic.

Uncertainties

The data generated from this research provide an initial observation of TRWP in PM2.5 using methods that are specific to tyre tread, however, they are site specific and may not be applicable more broadly given the small sample size and consequent low statistical power. The calculation of the TRWP concentration involves the assumption of 50% of the polymer in the tread and 50% of tread in the TRWP. However, the 50% assumption of tread in the TRWP is based on the characterisation of bulk TRWP in the size range of 0–150 μm. As such, the composition of the <10 μm fraction has not been specifically characterized.

It is currently unknown if the use of the 50% tread assumption overestimates or underestimates that composition in the <10 μm particles. Previously, the tyre wear contribution to the PM2.5 fraction was evaluated using Aerosol Time-of-Flight Mass Spectrometer (ATOFMS) and the researchers concluded that there was both a pavement and tread component, although the researchers did not have a quantitative estimate of the amounts. More recently, roadside airborne particulate in the 10–80 μm range was characterised using SEM EDX and the researchers concluded that the amount of pavement encrustation of the surface area of the ‘tyre core’ (i.e., tread) ranged from approximately 10% to more than 50%. As such, more research may be needed to refine TRWP composition in the PM10 and PM2.5 fractions.

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Pirelli is set to play a central role as the FIM Superbike World Championship concludes the first half of its season this weekend at Donington Park for the UK Round. Marking the final event before the summer break, the Italian tyre manufacturer has equipped competitors with the softest rear compounds from its 2026 standard range. This selection represents a clear advancement in development from the previous year, when riders were limited exclusively to older specification tyres.

For the premier WorldSBK class, the rear tyre allocation is headlined by the SCQ extrasoft compound, intended primarily for qualifying and the Superpole Race. This option, the softest in Pirelli’s portfolio, has already garnered positive feedback from riders during the Emilia-Romagna Round for its exceptional single-lap pace and consistent performance over a sprint distance. Complementing the SCQ are the SCX supersoft and SC0 soft compounds, while front tyre duties are covered by the standard SC1 soft and SC2 medium solutions, with the softer front being the overwhelming preference of last year’s grid, including triple race winner Toprak Razgatlıoğlu.

The notoriously unpredictable British weather remains a critical variable, with cool morning temperatures and frequent rain showers posing significant challenges for teams. Pirelli’s range has historically demonstrated considerable adaptability across fluctuating track and air temperatures, maintaining reliable grip in both cooler and warmer conditions. To address potential precipitation, the allocation is supplemented by DIABLO Wet intermediate and full DIABLO Rain tyres for both front and rear positions, ensuring competitors have viable options regardless of the elements.

In the supporting categories, WorldSSP riders will retain the SCX and SC0 rear compounds alongside the SC1 and SC2 front options. Meanwhile, the WorldWCR field and the emerging talents of the Yamaha R3 World Cup will also be in action, with both series utilising the Pirelli DIABLO Superbike SC1 tyre on both axles throughout the weekend’s racing programme.

Giorgio Barbier, Pirelli Motorcycle Racing Director, said, “Donington Park is a very distinctive circuit and, in many respects, a unique venue on the FIM Superbike World Championship calendar. The opening part of the lap features a series of fast, flowing corners taken at high speed and rapid changes of direction that require riders to manage significant power while the bike is still heavily leaned over. This demands tyres capable of delivering outstanding grip, precision and stability while maintaining consistent performance over race distance.

"Compared with last year, when only standard range solutions were available and no development specifications were included, this season, while confirming the same compounds introduced in 2025, we will provide riders with the complete 2026 standard range. The SCQ extrasoft compound will be the softest option in the allocation and can be used not only in free practice and qualifying but also, potentially, in the Superpole Race. For the longer races, riders will be able to rely on the SCX supersoft and, should temperatures be lower, the SC0 soft compound – solutions that have already demonstrated throughout the season an excellent balance between outright performance and consistency, as reflected by the many new records that have been set.

"Finally, the weather, which has historically been unpredictable in the UK, will once again be a key factor. Rain and low temperatures, even in the middle of summer, can have a major influence on tyre management and race strategies. Having a complete and versatile range available will therefore be essential to provide the best possible support in any weather conditions.”

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Sri Trang Group has unveiled a comprehensive organisational strategy centred on its ‘Empowering AI’ mission, designed to integrate artificial intelligence across its operations to boost efficiency and foster long-term sustainability. The initiative was formally announced during the company’s flagship annual gathering, the Sri Trang Town Hall 2026, held at the Four Points by Sheraton Phuket Patong Beach Resort. The event drew over 1,700 participants, including executives such as the Chairman, Group CEO and other board members, alongside employees from domestic and international branches who attended both in person and virtually.

Central to the new vision is the Group’s commitment to leveraging AI and data analytics throughout its entire value chain, supported by a robust Enterprise Data Foundation and an AI Governance framework. These systems are intended to ensure meticulous data management and foster stakeholder confidence. The application of AI is being tailored to optimise specific operational phases, from upstream procurement and production to downstream sales and logistics, aiming for precision in market forecasting, quality control and customer responsiveness.

Parallel to its technological push, Sri Trang is prioritising the development of AI Agents and practical AI Use Cases to accelerate tangible business outcomes. This effort is complemented by a cultural shift towards an ‘AI x Human’ paradigm, preparing the workforce to collaborate effectively with intelligent systems. Concurrently, the Group is reinforcing its dedication to environmental, social and governance principles, focusing on resource efficiency and the management of energy, water, waste and emissions as part of its trajectory towards a Net Zero target.

To support its ESG goals, Sri Trang is enhancing data systems to align with international standards like ISO 14064-1, ensuring accuracy and auditability for better risk management and decision-making. The company is also expanding collaboration with suppliers through its ESG Partner approach to elevate industry standards. This strategic direction underscores Sri Trang Group’s ambition to solidify its status as an innovation-led entity, combining human potential with AI to drive the Thai natural rubber sector towards resilient and sustainable growth on the world stage.

Dr Viyavood Sincharoenkul, Chairman of Sri Trang Group, delivered a keynote address on the vision, stating, “AI will not merely be a tool; it will become part of Sri Trang’s way of working and decision-making. We are building the Sri Trang AI Factory to connect data, technology and people together. AI is not simply a new technology but a major transformation in the way we work and compete in business. As the world accelerates AI adoption, organisations and people that are able to learn, adapt and work effectively with AI will be the ones that gain a competitive advantage and achieve sustainable growth in the future. Our goal is not to have the best AI but to build an organisation where everyone can use AI effectively, supported by trusted data, proper governance and a culture of continuous learning. The success of AI is not measured by the number of systems developed but by the number of people who can work effectively with AI and create value for the organisation.”

Veerasith Sinchareonkul, Group CEO, Sri Trang Group said, “The ‘AI Revolution Without Boundaries’ does not mean bringing in technology to replace our people. Rather, it means using AI to enhance people’s capabilities so that they can work smarter, faster and more efficiently. In essence, the meaning of ‘Empowering AI’ is ‘Empowering People with AI’ empowering our people to grow and move forward through the potential of AI. We believe in the power of collaboration between humans and AI. When AI works alongside people at every level, it helps improve decision-making accuracy, enhance the efficiency of frontline employees, strengthen executive leadership and foster a culture of continuous learning, teamwork and innovation. The future of the organisation is therefore not one in which AI replaces humans, but one in which humans grow together with AI without limits.”

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Michelin has expanded its retail footprint in North India by inaugurating two Michelin Tyres & Services (MTS) outlets, located in Amritsar and Panchkula. The Amritsar location operates through a partnership with National Auto, while the Panchkula facility is a collaboration with Universal Tyres. This development underscores the French tyre giant’s strategy to place its globally recognised products and services within closer reach of consumers in a rapidly developing automotive market.

Each of the new establishments spans 5,000 square feet, situated strategically on Loharka Road and within Panchkula’s Industrial Area. Designed as modern service hubs, they provide a full spectrum of offerings, ranging from passenger car and two-wheeler tyres to advanced wheel alignment and mechanical maintenance. The stores stock renowned product lines such as the Primacy, Pilot Sport and Latitude Sport series, aiming to deliver a premium and seamless experience for vehicle owners.

The selection of Amritsar and Panchkula reflects Michelin’s assessment of their growth potential, driven by tourism, infrastructure projects and a rising number of private vehicle owners. To capitalise on these opportunities, Michelin has aligned with established regional players. National Auto, a trusted entity in Amritsar since 1927, brings a long-standing reputation for quality service, while Universal Tyres contributes over three decades of technical expertise and market knowledge in the Panchkula region.

These partnerships are central to Michelin’s broader objective of delivering superior mobility solutions rooted in safety and durability. By combining its own technological leadership with the local acumen of its partners, the company aims to strengthen its service ecosystem and cater to the evolving demands of the northern Indian automotive sector.

Shantanu Deshpande, Managing Director, Michelin India, said, “North India continues to be a key market in Michelin's growth journey, supported by rising vehicle ownership, improving road infrastructure and growing demand for premium mobility solutions. The launch of our new Michelin Tyres & Services Stores in Amritsar and Panchkula marks another important step in strengthening our retail presence and bringing Michelin's globally benchmarked products and services closer to customers across the region. As we prepare to introduce Made-in-India passenger car tyres, we remain focused on delivering solutions tailored to the evolving needs of Indian consumers.”

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Tyres Europe has issued a formal call for the Industrial Accelerator Act to be revised, urging policymakers to grant greater recognition to the tyre sector’s strategic importance within the continent’s automotive ecosystem. In a newly published position paper, the organisation argues that the current framework insufficiently addresses the industry’s unique contributions and challenges.

The association is advocating for several key amendments, including an expanded scope that acknowledges tyres as critical components in both the replacement and original equipment markets, thereby stimulating demand for EU-manufactured products. Additionally, Tyres Europe proposes the establishment of a Union origin definition that would prioritise European production in public procurement and state-aid schemes. The paper also highlights tyres’ potential to enhance energy efficiency and lower CO2 emissions for light vehicles, while calling for dedicated backing for retreaded and EU-made truck and bus tyres, alongside increased financial mechanisms for industrial decarbonisation and improved governance of manufacturing acceleration zones.

With these targeted modifications, Tyres Europe contends that the Industrial Accelerator Act could effectively foster a market for low-carbon, high-performance tyres produced domestically. Such adjustments would simultaneously bolster competitiveness, support decarbonisation goals and reinforce the overall resilience of Europe’s automotive supply chain.

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