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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Tegeta Green Planet opened the Light Vehicle Diagnostics course at Tegeta Academy with a presentation for attendees aged 17 to 33. Beyond their chosen vocational field, participants learned about automotive waste management and environmental responsibility.

Shalva Akhvlediani, the organisation’s director, outlined its activities and goals while emphasising Extended Producer Responsibility. The session examined how the automotive sector connects to environmental duty and why used tyres, waste oils and automotive batteries must be collected and managed properly.

Tyre management and RECSOL featured prominently. Attendees traced a used tyre’s path from collection to recycling and learned how waste becomes a source of new resources. RECSOL, Tegeta’s tyre recycling plant, is a significant infrastructure project in used tyre recycling, processing tyres into materials for various uses and supporting circular economy principles.

A core aim is a system where waste is not an endpoint but the starting point for new resources, which requires infrastructure alongside greater public awareness and information on proper disposal. For participants, the meeting linked professional education with environmental awareness, stressing that future automotive professionals should understand this responsibility early.

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Tyres Europe, alongside ACEA (the European Automobile Manufacturers’ Association) and CLEPA (the European Association of Automotive Suppliers), has dispatched a joint communication to EU decision-makers concerning the possible broadening of the Carbon Border Adjustment Mechanism (CBAM) to cover downstream goods. The move comes as trilogue discussions approach.

Tyre producers form part of an automotive value chain already bearing carbon-related expenses for steel and aluminium manufactured within Europe. The proposed expansion would draw additional products into the mechanism’s remit before the existing framework has demonstrated its effectiveness. Resulting costs and administrative requirements would land on downstream manufacturers, tyre makers included, with signatories cautioning that a conceptually sound regulatory effort could become an operational and financial strain.

Endorsing the mechanism’s aims, the signatories nonetheless urge a proportionate scope that shields the entire value chain from carbon leakage while preventing that risk from being pushed further downstream. They advocate extending the mechanism only where a material carbon-leakage danger is evidenced, and request that policymakers ease compliance demands, including via more fitting default values mirroring real production routes.

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NEXEN TIRE has extended its partnership with Zalgiris, reinforcing its commitment to basketball in Europe, particularly across the Baltic region. The renewal builds on a relationship that began in 2024 and reflects the company’s broader strategy of linking its brand to performance, innovation and mobility.

The tyre maker has pursued sports partnerships as a way to connect with fans, sharing in the passion and excitement of supporting favourite teams during major matches and memorable moments. It also values the teamwork, dedication and collective achievement that define team sports, using such ties to build authentic connections and deepen engagement in key European markets. Its collaboration with clubs including Zalgiris and FC Bayern München forms part of this approach.

Under the extended agreement, NEXEN TIRE will gain greater visibility among sports fans in the region. The partnership offers branding opportunities at Zalgirio Arena, such as synchronised on-screen advertising and promotion on LED stands near the court, in a position visible on television during EuroLeague and LKL home games.

The arrangement also includes a hospitality programme allowing NEXEN TIRE to welcome guests and business partners at Zalgiris home fixtures. Through the strengthened alliance, the company aims to share its passion with more fans while raising brand awareness across the region.

Ricky Lee, Managing Director, NEXEN TIRE Poland, said, “Our cooperation with Zalgiris has developed positively since 2024, and we are pleased to extend and strengthen this partnership. Basketball has a particularly strong following in the Baltic region, making Zalgiris an important partner as we continue to grow our presence and engage with fans. We look forward to supporting the team throughout the season and doing our best to create positive experiences for both the players and their passionate fans.”

Paulius Jankunas, President, Zalgiris, said, “We are delighted to continue our cooperation with NEXEN TIRE and build on the partnership we started two years ago. NEXEN TIRE brings extensive experience in sports marketing, and we are proud to work together on creating meaningful projects and experiences for our fans. We look forward to another successful period of cooperation and to welcoming NEXEN TIRE’s guests and partners to our games and events.”

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TBC Corporation, one of North America’s largest marketers of automotive replacement tyres through wholesale and franchise operations, has widened its tyre portfolio through the addition of four new lines under the Multi-Mile Tyres banner. Serving as a value step-up brand, Multi-Mile gives dealers a strong mix of broader product coverage and improved consumer advantages crafted to drive better retail margins, helping retailers offer greater value while lifting profitability. With this expansion, the portfolio now reaches over 85 percent of the vehicle market, offering dealers more ways to satisfy customer demand.

Among the additions are tyres built for rugged and mud terrain use, boasting self-cleaning treads that push out mud and stones alongside dependable traction both on and off the road. Also joining the range are commercial and C-metric speciality tyres tailored to heavy-duty regional and long-haul trucks, together with all-weather tyres that hold the 3-Peak Mountain Snowflake severe snow rating and are made for high mileage and consistent year-round use.

A prominent name in the replacement tyre segment, Multi-Mile carries cutting-edge touring, high-performance and broad-line tyres suited to passenger cars, light trucks and SUVs. Meanwhile, the upgraded Mile After Mile Protection Plan warranty now delivers broader coverage, adding three-year roadside assistance, a three-year road hazard protection plan and a 60-day ride guarantee on top of its extensive treadwear warranties.

Rachel Tibor, Chief Marketing Officer, TBC Wholesale, said, “For more than 70 years, Multi-Mile products have offered cost-efficient, reliable and durable tyre options that enhance safety and performance. With this expanded portfolio, Multi-Mile strengthens its position as a value step-up brand, giving dealers more opportunities to meet evolving consumer needs while offering a product mix designed to support stronger retail margins. We’re continuing our longstanding tradition of supplying the right products at the right time for every type of vehicle and application.”

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