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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Dunlop Motorcycle Europe is celebrating a successful conclusion to the 2026 Campeonato de España de Superbike (ESBK) campaign, with five of its equipped riders securing titles at the Sunday finale at Circuito de Jerez Ángel Nieto. The brand claimed five of the series' eight championships, four of them in open-tyre competition classes, after a tightly contested season spanning Spain and Portugal.

The ESBK's open-tyre rules in several classes give Dunlop a direct benchmark against competing manufacturers. The company backed riders throughout the year in Superbike, Supersport, Supersport 300, Superstock 600, Superstock 1000 and Pre-Talent. Four of those classes allow any tyre brand, while Dunlop is the sole supplier for Supersport 300 and Pre-Talent.

The Superbike, Superstock 600 and Pre-Talent crowns all remained undecided going into Jerez. Honda Laglisse's Javier Palomera clinched Superbike ahead of Dunlop-backed Ivo Lopes of BMW Easyrace Team, runner-up in the open-tyre class; the same squad also took Superstock 1000 through Mauro González. José Luis Armario won the last Superstock 600 race of the year, and in Supersport, Team Speed Racing's Marcos Ludeña placed second with Team Honda Laglisse's Yeray Ruiz third, giving Dunlop two of three open-tyre podium slots. In the Dunlop-only classes, Marc Vich took Supersport 300 and the Kawasaki Ninja Spirit Trophy, while Marcos Vinagre won Pre-Talent at Jerez, leading an all-Dunlop podium alongside Javier Vigueras and Jose Luis Cagigas.

Dunlop's ESBK programme uses its KR racing slick line, covering both development and catalogue specifications, with wet tyres also available. Data from real race weekends helps the brand validate new products before they reach other championships and track-day use. Dunlop's racing footprint also takes in the Campionato Italiano Velocità, which produced six more Dunlop champions in 2026, and the FIM Endurance World Championship, where a fresh multi-year deal makes Dunlop the sole supplier to the Superstock and Production Trophy classes.

Roberto Finetti, Marketing Manager, Dunlop Motorcycle Europe, said, “It's great to see Dunlop-equipped riders achieve such strong results in the 2026 ESBK season, with championship titles secured across multiple categories and two all-Dunlop podiums in Supersport 300 and Pre-Talent. We're incredibly proud of what our riders and teams have achieved this season and of the role Dunlop has played in their success. These results are a testament to their dedication and hard work throughout the year. Congratulations to all the newly crowned champions.”

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Tegeta Green Planet, in partnership with the United Nations Development Programme (UNDP), organised an information and practical campaign titled ‘Don’t Throw It Away, Hand It In’ in Poti. Held on 29 October at a Tegeta Motors branch, the initiative sought to strengthen environmental responsibility and promote proper management of specific waste streams.

The campaign targeted local residents, vehicle owners, drivers and private sector representatives, encouraging their active involvement in waste management. Attendees learned about the environmental impact of automotive waste and correct disposal methods. A dedicated collection point at the branch allowed residents to hand in end-of-life tyres, used batteries and waste oils, offering a practical way to contribute to environmental protection through everyday actions.

A significant focus was placed on raising awareness about the Extended Producer Responsibility (EPR) system, including the role of EPR organisations, collection and subsequent management of specific waste streams and importers’ legally established obligations. Symbolic gifts encouraged participation. Tegeta Green Planet and UNDP continue to implement regional environmental campaigns and educational initiatives aimed at raising public awareness, fostering responsible waste management and promoting circular economy principles.

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Bridgestone’s Potenza Sport EVO has earned two independent test accolades, strengthening the tyre maker’s standing in the ultra-high-performance segment. The double success spans a victory in What Car?’s summer tyre test and a Recommended award from evo.

In What Car?’s evaluation of 11 summer tyres, the Potenza Sport EVO ranked first. Fitted to a Volvo XC60, it drew praise for predictable handling and secure performance in wet and dry conditions, along with communicative steering suited to a premium performance tyre.

The What Car? results also underscored tyre choice’s safety implications. In wet braking, the Bridgestone stopped 7.3 metres shorter than the Goodride competitor. The publication concluded that the Potenza Sport EVO justified its higher price, highlighting the value of investing in quality tyres.

The evo test delivered further recognition. The Potenza Sport EVO finished second overall but secured the Recommended award and was arguably the standout performer across individual disciplines, taking five first-place finishes. It earned top subjective ratings for polished, effortless behaviour, excelled in wet grip, traction and stability and set the fastest handling-course time, becoming the only tyre to break 51 seconds.

Drew Chapman, Consumer Sales Director, Bridgestone UK, said, "To achieve such outstanding results in two highly respected independent tyre tests is a fantastic endorsement of the Potenza Sport EVO and the engineering that has gone into its development. Winning the What Car? test against 10 other competitors, while also securing evo's Recommended Award and five individual test victories, demonstrates the tyre's exceptional breadth of capability. These results reflect exactly what we set out to achieve with the Potenza Sport EVO; delivering outstanding performance, control and confidence in a wide range of driving conditions. It's hugely rewarding to see that recognised by independent experts."

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Citira, a Sweden-based company specialising in circular tyre management, has expanded its UK commercial service network by acquiring G & S Tyres Ltd, a move that also brings a modern retreading facility in the London metropolitan area into the group. The deal advances Citira's push towards a national UK footprint, building on its recent purchase of Redpath Tyres in Scotland and its entry into UK market earlier this year via Tyrefix Group.

G&S's local knowledge, solid reputation and retreading strengths align closely with Citira's circular tyre management model, which covers retreading, rim refurbishment and fleet logistics and is already well established across the Nordics and Poland. The East London site is strategically positioned and employs around 45 people.

A two-generation family firm with more than four decades of service to UK customers, G&S will keep trading under its own name with its existing team. Gary, James and Billy Short will stay involved in the business and take shareholdings in the Citira Group.

Oliver Johnson, Head of UK at Citira, said, “G&S Tyres has earned a strong reputation across the UK through its reliability, service quality and close relationships with the fleets and customers it supports. That reputation provides an excellent foundation for the next stage of growth. Following our acquisition of Redpath Tyres in Scotland, G&S is a further step in our ambition to build a national commercial tyre service network with the best people and businesses in the UK.”

Gary Short, speaking on behalf of the Short family, said, “We are very happy to join a group whose ambitions for the UK align so well with our own. Citira is a great home for G&S and gives us the right platform to support the next generation, spearheaded by James and Billy, as they continue to grow and improve the business.”

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