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 recently conducted an educational workshop at AlterBridge University, focusing on sustainable development, the Sustainable Development Goals and the Extended Producer Responsibility system. The session provided students with essential knowledge regarding proper waste management and the environmental consequences of daily consumer choices.

Organised in partnership with Shine Energy, the event featured an interactive format that included a discussion segment, an engaging game and a concluding ceremony to recognise the workshop's top performers. This collaborative effort aimed to make the learning process both informative and participatory.

As a pioneering entity in Georgia, Tegeta Green Planet holds official authorisation from the Ministry of Environmental Protection and Agriculture under the EPR framework. The organisation is actively involved in the circular economy by managing the collection, transport and recycling of used tyres, oils and batteries.

Throughout the workshop, students posed inquiries to industry experts and explored how personal actions influence ecological well-being. Attendees received symbolic gifts and certificates for their participation. This initiative is part of a broader educational campaign by the organisation to visit universities and schools throughout Georgia, with the ultimate goal of fostering environmentally conscious citizenship among the youth.

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The Tire Industry Project (TIP) has initiated a pilot study in collaboration with the Greater Paris Sanitation Authority (SIAAP) and the sustainability consultancy ERM to assess the potential of wastewater treatment plants to remove tyre and road wear particles. The research is being conducted at the Valenton wastewater treatment facility near Paris, which ranks as Europe’s second-largest plant and features advanced treatment technologies representative of modern municipal systems. This investigation is scheduled to continue through 2026.

In numerous urban centres globally, stormwater and road runoff are channelled into wastewater systems prior to being discharged into natural waterways. A clearer understanding of how effectively these treatment processes capture TRWP could guide the broader adoption of optimised wastewater management practices. Currently, systematic data quantifying the removal of these particles within treatment plants remains scarce, and this project aims to generate comprehensive, end-to-end evidence to bridge that knowledge deficit.

The study represents TIP’s first real-world application of a priority mitigation strategy identified in its white paper on addressing tire and road wear particles. Over the coming months, researchers will collect and analyse samples from key stages of the Valenton plant’s treatment cycle using advanced pyrolysis gas chromatography-mass spectrometry. The findings are expected to estimate the total removal efficiency across the entire process and will be submitted to a scientific journal, with publication anticipated in early 2027.

The scientific understanding of TRWP is complicated by a lack of standardised methodologies, the variable nature of the particles and their transformation products, and the diverse environmental pathways they traverse. In response, TIP and its member companies have committed to advancing research on quantification, characterisation, environmental migration and potential impacts while collaborating with value-chain stakeholders to support science-based interventions. A 2024 TIP publication reviewed over 50 mitigation measures and prioritised nine based on upstream and downstream potential, employing a prevention, containment and removal framework.

That review also concluded that no single measure has been proven effective specifically for TRWP and that on-ground validation is essential. Moreover, the paper stressed that no universal solution exists, requiring coordinated, large-scale implementation across multiple actors, including the tyre, road construction and automotive sectors, as well as municipal authorities, academia and other public and private entities. The Valenton pilot thus marks TIP’s inaugural effort to test wastewater management’s real-world efficacy, uniting diverse stakeholders from both the public and private sectors in this critical research.

Larisa Kryachkova, Executive Director, TIP, said, “This pilot is an important step in going beyond understanding the subject in the laboratory to field-based evidence. We expect to identify best practices that can be applied far beyond this project, supporting TIP’s ambition to support science-based mitigation.”

Sabrina Guérin, Head of Innovation Department, SIAAP, said, “As the public authority responsible for wastewater treatment in the Paris region, SIAAP is committed to emerging science that protects waterways. By taking part in this TIP study, we will gain an early, science-based view of TRWP movement in solid waste. The findings can help inform and accompany future treatment planning and readiness for upcoming regulatory requirements.”

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Falken has been named the recipient of the prestigious BRV Service Award, as announced by the German Tyre Retail and Vulcanisation Trade Association during its General Meeting on 8 June 2026. As a brand operating under Dunlop Tyre Europe GmbH, Falken emerged victorious from a competitive online survey where over 250 tyre trade members cast their votes to determine the industry’s most outstanding partner.

This accolade specifically recognises Falken’s superior service standards and its commitment to fostering a reliable and cooperative relationship with its retail partners. The overwhelming vote of confidence from the trade serves as a significant form of recognition for the company, while simultaneously acting as a powerful incentive for the entire Falken workforce to maintain their high-performance levels.

Thomas Langer, Sales Director Germany, Dunlop Tyre Europe GmbH, said, “The news of a top ranking in the BRV Service Award was already a special honour, as it comes directly from the specialist tyre trade. We are now even more delighted to celebrate the overall victory. We would like to express our sincere thanks for this recognition. First place confirms our commitment to offering Falken partners not only reliable and safe products, but above all, dependable service, personalised support and a truly partnership-based collaboration. The fact that the trade has voted the entire team’s efforts into first place motivates us to continue pursuing our goals with determination.”

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The Alliance for the Future of Tires (AZuR) has concluded its participation at The Tire Cologne 2026 with a positive assessment, operating through a network of 19 affiliated organisations across Europe. Their shared exhibition space in Hall 7.1 emerged as a central meeting point during the industry's premier global gathering. Key episodes included a governmental visit, a strategic industry forum and recognition for emerging enterprises.

An immersive installation greeted visitors to the AZuR area, with the entire floor surface consisting of resilient tiles produced from recycled tyre rubber supplied by network affiliate MRH Mülsen. This practical display offered a compelling illustration of how discarded materials can be transformed into functional products. The collaborative exhibition model proved highly favourable among attendees and participating companies alike.

The initiative broadened its collaborative base during the fair, securing commitments from new entities in Germany, Belgium and the Netherlands to advance shared sustainability objectives. North Rhine-Westphalia's environment minister, Oliver Krischer, toured the exhibition as part of a broader initiative to spotlight regional excellence in circular practices, observing demonstrations spanning digital monitoring, alternative materials and recovery processes.

A dedicated assembly on tyre retreading drew roughly 40 specialists from manufacturing, materials supply and trade associations. Conversations revolved around the technology's track record and adaptation to market conditions, referencing recent environmental performance data. Survey feedback indicated robust confidence in retreading's financial and environmental merits, though participants identified competition from lower-cost imports as a primary obstacle.

The programme concluded with the LOOP THE TYRE competition awards. The top honour went to Machine-Vision.io from Reutlingen for its optical evaluation system streamlining used tyre assessment. Sustainable Rubber Solutions from the Netherlands received second prize for its chemical innovation enabling rubber reintegration into new compounds, while Austria's ReTyre project claimed third for developing a scalable devulcanisation method for tyre-to-tyre recycling.

Anna-Maria Guth, AZuR Network Coordinator, said, “TTC impressively demonstrated the high level of interest in a functioning tyre circular economy. We were particularly pleased with the exceptionally positive atmosphere at our joint stand. Our partners see themselves as equal contributors to a common goal and as partners in a strong alliance for the future.”

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