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.

Comments (0)

ADD COMMENT

Link Copied!

Hankook Tire concluded Round 2 of the 2026 FIA World Rally Championship, Rally Sweden, on 15 February in the Umeå region, where its Winter i*Pike SR10W tyre was put to the ultimate test. As the championship’s sole rally tyre supplier, Hankook equipped all competing crews with this dedicated winter tyre, which features specially engineered ice-rally stud pins. Designed to conquer the most severe icy environments, its asymmetric tread pattern works in tandem with the studs to provide exceptional grip, powerful braking and unwavering high-speed stability on frozen surfaces.

Rally Sweden, first held in 1950, is unique on the calendar as the only event contested entirely on snow and ice. Crews were challenged by 18 special stages covering around 300 kilometres, with competition intensified by speeds reaching up to 200 kmph and rapid temperature fluctuations. These punishing conditions demanded precise car control, reliable tyre traction and steadfast braking performance, making the choice of the Winter i*Pike SR10W critical for success.

Following a fierce contest, Toyota GAZOO Racing’s Elfyn Evans and co-driver Scott Martin claimed victory by a margin of 14.3 seconds, securing their second consecutive win in Sweden. Having also finished second in the season opener at Rallye Monte-Carlo, this result propelled the pairing to the top of the championship standings with 60 points.

The WRC now turns its attention to the formidable Safari Rally Kenya, scheduled for 12 to 15 March 2026 near Naivasha. This event is renowned as one of the most gruelling on the circuit, where crews must navigate extreme heat, mud from heavy rainfall and rapidly changing weather.

Hankook’s commitment to the sport extends beyond event supply. The company continues to refine its high-performance rally technology through intensive collaboration with the FIA and major automotive manufacturers, having completed over 2,000 kilometres of real-vehicle testing across eight countries. With its exclusive tyre supply agreement for all WRC classes covering the 2025 to 2027 seasons, Hankook is reinforcing its premium brand identity and solidifying its leadership in motorsport engineering.

Comments (0)

ADD COMMENT

Link Copied!

Ecolomondo Corporation, a leading Canadian innovator in sustainable scrap tyre recycling technology, has appointed Craft Capital Management, LLC as its strategic investment banking advisor. This partnership is designed to bolster Ecolomondo’s capital markets strategy, with a focus on financing initiatives and a planned uplisting to the NASDAQ. Securing this position is a key step for the company to obtain the necessary capital for its global expansion.

Eliot Sorella, Ecolomondo’s Executive Chairman, highlighted that Craft Capital’s successful history of providing capital solutions is well-aligned with the company's goal to scale up as a major supplier of recovered carbon black and tyre pyrolysis oil. These materials are produced using Ecolomondo’s proprietary Thermal Decomposition Process. As worldwide demand for circular and sustainable materials grows, this advisory engagement is seen as a vital move to advance the company's market position and support its next growth phase.

Craft Capital, a full-service brokerage firm with over a century of combined financial experience, offers customised investment banking services and connects clients to a broad network of family offices and institutional investors.

Sorella said, “Craft Capital’s proven track record in delivering capital solutions aligns strongly with our strategy to scale as a leading producer of recovered carbon black (rCB) and tyre pyrolysis oil (TPO) using Ecolomondo’s proprietary Thermal Decomposition Process (TDP). As global industries accelerate their transition towards circular and sustainable materials, this engagement is an important step in advancing our capital markets strategy and supporting our next phase of growth.”

Comments (0)

ADD COMMENT

Link Copied!

Continental is set to make a significant impact at the upcoming Tire Technology Expo in Hannover with a strong presence at the technical conference scheduled for 3 March 2026. The company will kick off the event with a major presentation centred on the evolution of tyre technologies designed to meet the demands of autonomous driving. Dr Andreas Topp, who leads Platform Development and Industrialisation for passenger car tyres at Continental, will illustrate how the vision of autonomous vehicles is transitioning into everyday reality and how the tyre manufacturer is proactively developing innovative solutions to support this shift.

In addition to the opening session, Continental experts will deliver three further presentations, each addressing critical areas of tyre science and environmental regulation. One of these will explore the use of recovered carbon black derived from end-of-life tyres as a filler material. Professor Jorge Lacayo-Pineda, a specialist in materials evaluation, will delve into the complexities of identifying this material within vulcanised rubber compounds. Recovered carbon black, primarily obtained through pyrolysis, represents a milestone as the first industrially scalable filler sourced from discarded tyres. It is not considered a direct substitute for conventional carbon black but rather a distinct category of filler due to its unique composition, which includes carbon residues and a specific thermal background. Professor Lacayo-Pineda will examine the technological and regulatory possibilities that arise from detecting this material in new tyre compounds, focusing on reliable identification techniques such as electron microscopy and molecular spectroscopy.

Another key presentation will broaden the conversation around tyre emissions. Dr Frank Schmerwitz, a senior test engineer specialising in tyre wear, will address the limitations of current discussions that predominantly focus on tyre and road wear particles. He will highlight additional pathways of mass loss that are not captured by conventional measurements. His talk will consider the release of nanoparticles, the persistence of wear residue on road surfaces and the chemical degradation of this material due to environmental factors like oxygen and ultraviolet light, aiming for a more complete scientific picture.

The final presentation will tackle the complexities of modern tyre development in the context of new regulatory frameworks. Dr Pavel Ignatyev, an expert in rubber friction and wear physics, will discuss how the introduction of standardised abrasion limits and measurement methods under the Euro 7 regulation is reshaping innovation in the industry. He will explain the various parameters influencing tyre wear and how they interact with these new requirements. Through simplified models, he intends to demonstrate the intricate nature of tyre wear and outline the collective challenges that remain for the industry, emphasising that a deep understanding of these dynamics is crucial for translating regulatory mandates into effective technological advancements.

Dr Topp said, “The future of self-driving vehicles has begun. We are developing tyre technologies and products that meet the unique technical requirements of these vehicles. This includes topics such as interaction with smart vehicle dynamic controls, optimised fleet operations and tailored solutions for specific use profiles.”

Comments (0)

ADD COMMENT

Link Copied!

The concluding day of 2026 F1 Pre-Season Testing at the Bahrain International Circuit saw Charles Leclerc set the overall fastest lap of the entire six-day programme. The Ferrari driver delivered a time of 1:31.992s on the C4 compound Pirelli tyres during the final hour of running, improving by eight-tenths of a second on the previous benchmark established by Kimi Antonelli. This performance placed him ahead of Lando Norris in the McLaren, who recorded a 1:32.871s on the C3 tyre. Max Verstappen and George Russell followed, with times of 1:33.109s and 1:33.197s, respectively, both also set on the C3 compound. Notably, none surpassed Leclerc's own leading time on that particular compound, a 1:32.655s. Pierre Gasly rounded out the top times, utilising the softest C5 tyres to post a 1:33.421s.

The C5 compound saw limited use on the final day, employed only by Alpine and Williams for short-run simulations. Aston Martin, despite having the tyre available, opted not to run it and instead completed just six laps on C3s before their session was curtailed. In contrast, teams focused on different aspects of performance. Gabriel Bortoleto and Arvin Lindblad set the pace on the harder C1 and C2 compounds, respectively. The day was also notable for the absence of several drivers, including Fernando Alonso, Lewis Hamilton and Alex Albon, who did not participate in any track action.

Beyond outright speed, teams dedicated significant effort to long-distance evaluation. Gabriel Bortoleto completed 25 laps on the C2 compound for Audi, while Esteban Ocon undertook 24 laps on C1s for Haas. Ocon was also the sole driver to run intermediate tyres, completing four laps to assess front wing behaviour. Over the entire six-day test, a total of 41,366 kilometres were covered across all 11 teams, a distance exceeding the Earth's circumference. The C3 compound proved the most popular, accounting for 61 percent of all laps. In total, 591 sets of slick tyres were utilised throughout the pre-season, with 326 of those deployed in the final three days alone.

Mario Isola, Pirelli’s Motorsport Director, said, “The radical changes introduced to the cars have inevitably shifted the teams’ focus towards power units and aerodynamics rather than tyres over the last few days. The final stages of testing are usually dedicated to optimising the car-tyre package, but it is clear some teams haven’t reached that point yet. Generally speaking, track feedback has been consistent with our simulation expectations. Drivers were able to gain confidence with the entire Pirelli range through both performance trials and long runs, even using the C4 and C5 compounds which aren’t particularly suited to a circuit like Sakhir.

“Mechanical resistance appeared strong across all options, with no signs of graining or blistering. Degradation levels are almost certainly higher now than what we expect for the Bahrain race, when temperatures will be lower and cars more developed. A central theme this season will certainly be balancing temperatures between the axles, especially ahead of the first race in Melbourne. The lower loads of a street circuit might require more intensive tyre preparation or differentiated tyre blanket temperatures, particularly in qualifying. In any case, it will be interesting to discover in Australia how much teams have been ‘sandbagging’ their engine power to avoid showing their hand. We only have to wait a couple of weeks to see the true pecking order.”

Comments (0)

ADD COMMENT

Link Copied!