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.

Goodyear has earned the prestigious ‘Master’ supplier rating by DAF for the fourth consecutive year.

Goodyear's excellence in crucial areas including product development, operational support and alignment with DAF's business objectives is highlighted by this recognition, which is a component of DAF's Supplier excellence Management (SPM) programme. Three performance categories – Achiever, Leader and Master – are used by the programme to assess vendors. The highest honour, the ‘Master’ rating, is given to suppliers that continuously exhibit exceptional performance and cultivate a close working relationship with DAF. By retaining the ‘Master’ rating for the fourth year, Goodyear underlines its position as a reliable industry partner committed to enhancing customer performance and efficiency.

Xavier Fraipont, Vice President Commercial PBU EMEA at Goodyear, said, “We are honoured to receive the ‘Master’ rating from DAF for the fourth consecutive year. This achievement reflects the dedication of our teams in delivering high-performing products and reliable support to DAF. It also underscores the strength of our long-standing partnership, built on a foundation of premium quality, innovations and collaboration.”

Apollo Tyres NL BV plans to close its Enschede manufacturing facility in the Netherlands by mid-2026, citing unsustainable production costs and declining demand for its speciality tyres.

The Dutch tyre manufacturer, a subsidiary of India-based Apollo Tyres Ltd, has formally submitted a Request for Advice to the Works Council regarding the intended closure, the company said in a statement Friday. The decision follows "thorough investigation and careful consideration" after cost-cutting initiatives failed to offset rising inflation.

"Submitting the Request for Advice to the Work's Council on the intended decision to discontinue production has been enormously difficult," said Benoit Rivallant, President of Apollo Tyres NL. "In the last few years, we have implemented several initiatives to reduce costs at Enschede. These initiatives resulted in some savings, but most were completely negated due to the ever-increasing inflation."

According to the statement, the Enschede plant, which produces pneumatic tyres for cars and agricultural vehicles, has struggled with "macro-economic disruptions, steep increases in energy and labour costs, and a decline in demand for Spacemaster and Agri tyres. " Pressure from low-cost competitors has further squeezed margins.

The company said it would continue normal operations while consulting with the Works Council and that the final decision remains subject to supervisory board approval. Management has committed to maintaining communication with employees, customers and suppliers throughout the process.

Apollo Tyres Ltd, headquartered in Gurugram, India, ranks among the leading tyre manufacturers. The company did not specify how many jobs would be affected by the closure.
    
 

The Rubber Research Institute of India (RRII), a research organisation working as part of Rubber Board, has announced its proposal to appoint a ‘Research Associate (statistician)’ to work in the Botany Division on temporary basis. The selection will be based on a written test cum walk-in interview.

Candidates must hold a Master’s degree in Agricultural Statistics or equivalent qualification to be eligible for the position. As per the criteria, the age of candidates applying for the position should not exceed 35 years as of 31 January 2025.  Interested candidates are advised to meet the Director of Research, Rubber Research Institute of India, Rubber Board, Kottayam–9 on 6 May 2025 at 9.30 am along with the original documents their age, educational qualifications, experience etc. Those interested can contact on 0481-2353311 or visit www.rubberboard.gov.in for further details.

Vaculug Ltd has officially launched its new mobile application, V-Torque, to support fleet managers and commercial vehicle technicians across the UK.

V-Torque is intended to improve the effectiveness and safety of vehicle maintenance by giving commercial vehicles weighing more than 7.5 tonnes operating in the UK instant access to wheel nut torque requirements and re-torque settings. Thanks to the app's sophisticated capabilities, users can oversee and control re-torquing procedures with unparalleled precision, guaranteeing the highest level of wheel security compliance. V-Torque lowers maintenance costs and advances fleet operations' sustainability objectives by optimising these procedures. After successful field tests with a few chosen service providers, the app is now accessible on the Google Play Store and the Apple App Store.

Glenn Sherwood, Chief Growth Officer of Vaculug Ltd, said, “We are thrilled to introduce V-Torque, a product born from our unwavering commitment to sustainability and innovation. The app amplifies our dedication to driving positive change in the industry.”