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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MAXAM Tire has further expanded its off‑the‑road tyre portfolio by adding a new 45/65R45 size to the MS406 E4/L4 series. This larger variant is specifically engineered for heavy loader applications, offering operators an additional high‑performance solution that prioritises strength, longevity and cost efficiency over the long term.

The tyre’s deep E4/L4 tread pattern is designed to deliver strong traction while resisting wear and cuts, even in severe working conditions. This aggressive yet durable design helps loader fleets boost productivity, as the tyre maintains grip and reduces downtime. Over its service life, users can expect a lower cost per operating hour.

To withstand harsh job sites, the MS406 incorporates a thick undertread that provides enhanced puncture protection. Its robust casing not only endures heavy use but also supports excellent retreadability, further extending the tyre’s usable life and improving overall return on investment. A wide, flat footprint contributes to superior stability, ensuring dependable performance and operator confidence when the vehicle is under substantial loads.

With this new size addition, MAXAM Tire continues to strengthen its off‑the‑road product line, giving customers another valuable option that balances durability, traction and long‑term operating efficiency in demanding loader environments.

Jimmy McDonnell, Vice President – Sales and Marketing, MAXAM Tire North America, said, “With the addition of the 45/54R45 size, we’re continuing to respond directly to market needs while expanding access to a proven loader tyre. Our focus is always on delivering market-leading value and tyres that perform in real-world conditions while helping customers control operating costs.”

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Hankook Tire, the exclusive tyre supplier for the FIA World Rally Championship, will face the demanding Croatia Rally from 9 to 12 April 2026. This event marks round four of the season and takes place in and around the port city of Rijeka. Among the most gruelling rallies on the calendar, it will feature both the Ventus Z215, engineered for precise dry handling and cornering stability, and the Ventus Z210, designed to deliver superior traction and rapid water evacuation in wet and unpredictable conditions.

The 2026 route spans roughly 300.28 kilometres across 20 special stages, with the service park relocated to the historic Grobnik Circuit. The course covers four counties, including shakedown stages on the island of Krk and technical tests through the Lika-Senj highlands. Drivers must contend with extreme grip variations along the Adriatic coast, from abrasive volcanic tarmac in the mountains to smoother, dustier sections near the sea, the latter becoming dangerously slick with even light rain.

Throughout the event, Hankook will operate its Brand World marketing booth inside the service park, reinforcing its unified global premium image. The booth will offer interactive experiences such as a motorsports history zone, racing simulator, tyre fitting activities, merchandise sales and a photo zone, giving fans an immersive brand encounter. Meanwhile, intense competition is expected: while Toyota GAZOO Racing has a strong history in Croatia, both Hyundai Shell Mobis World Rally Team and M-Sport Ford World Rally Team aim to exploit the new coastal terrain to challenge for the podium.

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Sri Trang Agro-Industry Public Company Limited has earned a total of 23 CSR-DIW awards, demonstrating its longstanding commitment to operating with ongoing responsibility towards society, local communities and the environment. In 2025, the Department of Industrial Works honoured the company under the CSR DIW to MIND for Sustainability programme, which recognises industrial factories that enhance their social and community responsibility for sustainable coexistence.

Among these accolades, five facilities received the CSR DIW Award for maintaining these high standards continuously for a decade, while another 18 facilities received the CSR DIW Continuous Award for consistently implementing responsible practices, collectively celebrating industrial organisations that serve as models for industry growing in harmony with communities under the principle of good industry coexisting sustainably.

These achievements reflect how the Sri Trang Group balances economic, social and environmental priorities, allowing the industrial sector to work alongside communities effectively and advancing Thailand’s rubber industry towards a sustainable green future. The group has steadily carried out community focused and socially responsible initiatives across six key areas, including youth development, arts and local traditions, livelihood and career support, environmental management, workplace health and hygiene as well as disaster relief and assistance for vulnerable groups.

This recognition further underscores Sri Trang Agro Industry’s role as a leading organisation that drives sustainable industrial practices while consistently creating lasting value for society, communities and the environment.

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Bridgestone has announced its participation in the 41st Space Symposium, the largest space conference in United States, taking place in Colorado Springs from 13 to 16 April 2026. The company’s exhibit will be hosted within the Japanese Space Industry pavilion organised by Japan Aerospace Exploration Agency (JAXA), marking its third consecutive year at the event since 2024. A key focus of Bridgestone’s presence is its ongoing development of lunar rover tyres, a project that embodies the company’s belief that ‘tyres carry life’.

Since 2019, Bridgestone has advanced research on lunar rover tyres and pursued co-creation with international partners to commercialise space mobility technology. In 2024, the company collaborated with Astrobotic Technology, followed by a basic agreement with ispace in 2025. These efforts aim to generate new value in the rapidly evolving space mobility sector.

At the symposium, Bridgestone will demonstrate tyres for small and medium lunar rovers, first unveiled in 2025, by mounting them on a mobility vehicle. Attendees can see and touch the tyres, experiencing their high traversability on simulated lunar challenges like fine sand and rocky ground. Through this showcase, Bridgestone seeks to expand its space business network and foster co-creation opportunities, ultimately supporting safe lunar mobility and humanity’s exploration goals.

The lunar rover tyre project applies Bridgestone’s AirFree technology, an exploratory business under its 2024–2026 Mid Term Business Plan. By refining this technology in the extreme lunar environment, the company aims to eventually bring those innovations back to Earth, enhancing conventional tyres and contributing to broader social value.

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