Search Results (20)

Tyre and road wear particles (TRWPs) represent one of the most significant yet under-recognised sources of global microplastic pollution, contributing up to 28% of total emissions. Generated from the complex interaction between vehicle tyres and road surfaces, TRWPs are chemically diverse, morphologically heterogeneous, and environmentally persistent, making their detection and management particularly challenging. This review provides a critical synthesis of current knowledge on TRWP generation mechanisms, influenced by tyre composition, road types, and vehicle operation, and their environmental dispersion through air, stormwater runoff, snow removal, and roadside deposition. The chemical and physical complexity of TRWPs—often composed of rubber, bitumen, road paint, and heavy metals—necessitates multifaceted analytical approaches. We synthesise current advancements in TRWP identification techniques, including microscopy, micro-spectroscopy, and thermal desorption methods, while benchmarking their applicability using ISO standards. Furthermore, we develop an integrated framework synthesising current classification schemes, detection strategies, and regional policy responses for TRWP assessment. By identifying analytical and regulatory gaps, this review highlights the need for harmonised methodologies, improved analytical comparability, and coordinated policy interventions to address the environmental and health implications of TRWPs. Full article

Tire and road wear particles (TRWPs) are formed at the frictional interface of the tire and road surface and consist of polymer-containing tread with pavement mineral and binder encrustations. Their detection in various environmental compartments globally sparks increasing societal and regulatory interest. Solid quantitative information as a basis for managing and mitigating TRWPs in the environment is lacking however. This paper presents and demonstrates a model approach that produces catchment-scale terrestrial and aquatic TRWP mass balances anywhere in the world. A spatially and temporally explicit modelling method was used that builds on publicly available global datasets and process-based open-source modelling frameworks to describe hydrological processes, TRWP releases, fate and transport under a wide range of climatic conditions. High-resolution (<1 km) models were implemented and evaluated by demonstrating consistency with available field data for three watersheds on different continents. The approach provides comprehensive mass balances to underpin management of TRWPs that account for socio-economic, climate, geography and stormwater management gradients. Case study results revealed strong climate-induced differences: the fraction of vehicle-generated TRWPs exported to the estuarine environment varied between 2% (Seine watershed, France) to 18% (Yodo River watershed, Japan), corresponding to an increase in the fraction released to freshwater ecosystems from 20% to 36%, respectively. The modelling framework provides a consistent comparison between watersheds across the world. Limitations of the approach are its lack of local details and the uncertainties stemming from the still-developing scientific knowledge base. Full article

The focus of this article is on the measurement of tire and road wear particles (TRWPs) during vehicle operation. The long-term objective is to determine the sources of particulate matter. Consequently, the development of sustainable tires can be supported in the future by identifying factors influencing the concentration of particulate matter in vehicle-based tire tests. In an initial campaign, a test vehicle was equipped with a total of seven low-cost sensors (LCSs) for measurement campaigns on an isolated outdoor test track. The purpose of this was to evaluate the particle measurements in combination with GNSS data and driving data such as acceleration and speed. The potential observed in the initial investigation led to further investigations with an advanced, interconnectable modular particle and environmental sensor system (iMPES), which was developed in-house. The iMPES records measurement data for PM10 via the PMS7003 and PM100 via the SDS198 at 1 Hz over a period of up to 6 h, using a mobile power supply. The findings of the study indicate a robust characterization of the particle concentrations over the temporal and local course of the campaign drives. The results demonstrate the potential of the method to be part of a methodology to differentiate the particle sources and to derive influencing factors on the particulate matter concentration. The paper proposes a methodology for the mapping and analysis of lap-based data on a normalized route. Consequently, an inquiry into the local and driving-dependent dynamics is conducted, alongside a comparison with driving data. Full article

(1) Car tyre microplastic particles (TMPs) significantly contribute to global microplastic pollution, with an estimated annual production of 6 million tonnes. However, the impact of TMPs, particularly tyre and road wear particles (TRWPs), resulting from tyre abrasion on the road on terrestrial organisms, is poorly understood. This study investigated the effects of TMPs and TRWPs on the growth, immune response, behaviour, and cognition of the woodlouse Armadillidium pallasii over 30 days; (2) TMPs and TRWPs were mixed together in the first experiment and provided at different concentrations of 1.25%, 2.5%, 5%, and 10% (w/w), and with soil at 5% and 10% (w/w) concentrations in the second experiment. (3) No differences in survival or immune responses were observed in both experiments. However, isopods exposed to TRWPs showed significant weight gain at lower concentrations but no gain at higher levels. Behavioural tests revealed increased vigilance in TRWP-exposed animals. Micro-FTIR analysis showed that the number of TMPs and TRWPs in the isopods correlated with soil concentrations, and particle size decreased during the experiment. (4) The study highlights the physiological and behavioural effects of TRWPs and the role of detritivorous species in the biofragmentation of TMPs and TRWPs, contributing to the biogeochemical plastic cycle. Full article

This study aims to evaluate the tire–road-wear particles (TRWPs) and suspended dust generated based on the nominal maximum aggregate size (NMAS) of the polymer-modified stone mastic asphalt (SMA) mixtures indoors. The SMA mixtures containing styrene butadiene styrene (SBS) polymer and the NMASs of 19, 13, 10, 8, and 6 mm were used. Dust was generated from the wear of the tires and the pavement inside the indoor chamber by using the laboratory tire–road-wear particle generation and evaluation tester (LTRWP tester) developed by Korea Expressway Corporation (KEC). In this method, a cylindrical asphalt-mixture specimen rotates in the center, and a load is applied using three tires on the sides of the test specimen. During the test, a digital sensor was used to measure the concentration for each particle size. After the test was completed, the dust was collected and weighed. According to the test results, the generated TRWP emissions were reduced by approximately 0.15 g as the NMAS of the SMA mixture decreased by 1 mm. TRWP emissions decreased by 20% when using the 6 mm SMA mixture compared to the 13 mm SMA mixture. For practical application, a predicted equation of TRWP emissions estimation was developed by using the concentration of suspended dust measured by the digital sensor in the LTRWP tester. LTRWP can be used as an indoor test method to evaluate pavement and tire materials to reduce the amount of dust generated from tire and pavement wear. Full article

As fleet electrification progresses, vehicles are continuously becoming heavier, while the used electric motors, with their high torques, enable longitudinal dynamics to be maintained or even increased. This raises the question of what effect electric vehicles have on the emission of tire–road particulate matter (PM). To answer this question, investigations were carried out in this study on a tire internal drum test bench with real road surfaces. In addition to the vertical load, the tire inflation pressure and the driving speed were varied. PM emissions were recorded in real time, resulting in emission factors (emission per kilometer driven) for different load conditions. This allows statements to be made about both the effect on the total emission and on the particle size distribution. It was shown that the PM emission increases linearly with the vertical load at constant longitudinal dynamics. If the tire inflation pressure is increased, the emission also increases linearly, and the increases in emission are equally large for both influences. A clear influence of the driving speed on the emission factor could not be determined. With regard to the particle size distribution, the following correlations were found: higher vertical load and higher tire inflation pressure result in a larger mean particle diameter, while a higher driving speed reduces it. Thus, this study contributes to a better understanding of the expected changes in tire-road PM emissions as a result of electrification. Full article

Tyre particles are generated by shear forces between the tread and the road or by volatilisation. Tyre abrasion (wear) contributes from one-third to half of microplastics unintentionally released into the environment. The major part ends up in the soil, a considerable amount is released into the aquatic environment, and a small percentage becomes airborne. Nevertheless, tyre abrasion contributes to 5–30% of road transport particulate matter (PM) emissions. This corresponds to approximately 5% of total ambient PM emissions. The particle mass size distribution peak at around 20 to 100 μm, with a second peak in the 2–10 μm range. A nucleation mode has been reported in some studies. The absolute abrasion levels depend on the tyre, vehicle, and road characteristics, but also on environmental conditions and driving style. Most tyre particle emission factors in the literature are based on data prior to the year 2000. We aggregated recent studies and found a mean abrasion of 110 mg/km per vehicle or 68 mg/km/t for passenger cars (based on approximately 300 measurements). Based on a limited number of studies, the PM₁₀ emissions were 1.4–2.2 mg/km per tyre. On the other hand, the particle number emissions were in the order of 10¹⁰ #/km per tyre. The ratio of PM₁₀ to total abrasion was found to be 2.5% on average. Finally, the ratio of PM_2.5 to PM₁₀ was calculated to be around 40%. Various mitigation measures for tyre particle pollution could be envisaged; the most direct is the limitation of the tyre abrasion rate, as proposed by the European Commission for the Euro 7 regulation. Other regulatory initiatives are also discussed. Full article

The objective of this study was to experimentally determine the mathematical correlations between the loading of the tire, being longitudinal and lateral forces, and the emission of particulate matter (PM) from the tire–road contact. Existing emission factors (EF, emission per vehicle and distance traveled) are the result of long-term measurements, which means that no conclusion can be drawn about the exact driving condition. To determine meaningful emission factors, extensive driving tests were conducted on an internal drum test bench while measuring PM emissions from the tire–road contact in real-time. This showed that the increases in emission over longitudinal and lateral forces can be approximated with fourth-order functions, with lateral forces leading to significantly higher emissions than longitudinal forces for the summer tire investigated. Using the emission functions obtained, a three-dimensional map was created that assigns an EF to each load condition consisting of different longitudinal and lateral forces for one vertical load. With known driving data, the map can be used for future simulation models to predict the total emission of real driving cycles. Furthermore, the results show that the average particle size increases with increasing horizontal force. The particles collected during the tests were analyzed to determine the proportions of tire and road material. According to the results, the tire contributes only about 20% of the particle mass, while 80% is attributable to the road surface. In terms of volume, these shares are 32% and 68%, respectively. Full article

Tire and road wear particles (TRWPs) are generated unintentionally while driving vehicles. The generated TRWPs move to various environments by environmental and mechanical action, and they are present in fresh water, river, and ocean and may cause problems to the environment and human health. In Korea, the number of registered cars is increasing year by year, so the problem of TRWPs will become serious. In this study, we study the concentrations of TRWPs generated from the roadsides by temperature difference, in order to reduce the generation of TRWPs. Dust samples were collected from roadsides during summer and winter to measure the amount of TRWPs generated on roadsides according to seasonal temperature changes. Dust particles of 75–150 µm size, which corresponds to the TRWP size, were separated from the dust samples using sieves. Additionally, only TRWPs were separated using a solution of dibromomethane and Trans-1,2-dichloroethylene. TRWPs accounted for <2% in the dust collected from roadsides, and their amount increased by approximately 7.6–24.2% in summer more than in winter. Thermogravimetric analysis results confirmed that the tire components and road components and minerals accounted for 30% and 70% in TRWPs regardless of the season, respectively. Full article

Plastic in the environment poses an increasing challenge. Microplastics, which include tire wear, enter the aquatic environment via different pathways, and increasing vehicle traffic leads to increased tire wear. This paper describes an approach for how inner-city tire wear hotspots can systematically be identified by sampling road-deposited sediments (RDS) by sweeping. Within the investigations herein described, six inner-city monitoring sites were sampled. The total masses of solids as well as the amount of styrene-butadiene rubber (SBR) representing Tire and Road Wear Particles (TRWP) were determined. It was shown that the sites differ significantly from each other with regard to SBR parts. The amount of SBR in the curve was on average eight times higher than in the slope, and in the area of the traffic lights, it was on average three times higher than in the slope. The RDS mass results also differ but with a factor of 2 for the curve and of 1.5 for the traffic light. The investigations and the corresponding results in this paper are unique, and the monitoring approach can be used in the future to derive and optimize sustainable measures in order to reduce the discharge of TRWP into the environment by road runoff. Full article

This study focuses on particulate matter emissions from tire–road contact and their investigation using an internal drum test bench. The test bench is equipped with real-road surfaces and has been upgraded to enable real-time measurements of particulate matter. It was found that the road surface changes during the tests due to constant rolling over, influencing the level of emissions significantly. To account for this effect, the micro roughness was characterized before, during, and after the tests. Specific emission values consisting of particle mass and number were determined with summer, all-season, and winter tires for different road conditions, as well as specific longitudinal and lateral forces. It turned out that emissions increase disproportionately with load for both force directions. The winter tire led to the highest emissions across all loads, and the summer tire led to the lowest ones. While lateral forces caused emissions many times higher than longitudinal forces for the summer tire, forces in both directions led to comparable emissions for the all-season and winter tires. Regarding the ambient temperature, a lower one seems to be favorable for summer tires and a higher one seems to be favorable for winter tires. Lastly, particle size distributions during different load conditions show a dependence on load, such that larger particles are emitted with increasing load. Full article

Tire and road wear particles (TRWP), which contribute significantly to microplastic emission, are receiving more attention, but details about particle composition, translocation from source to sink, and particularly the possible effects on ecosystems are largely unknown. We examined the influence of native TRWP-containing sediments from two settling ponds on the mortality and behavior of the aquatic larvae of Chironomus riparius. Both sediments, whether pure or mixed with different proportions of quartz sand and suspended in water, led to increased mortalities with increasing concentrations and were shown to be oxygen consuming. Artificial aeration significantly reduced larval mortality in both sediments. Chironomid larvae show high tolerance to anoxic and polluted environments due to physiological and behavioral adaptations, such as the construction of vertical sediment tubes (chimneys), in which they create oxic compartments. A significant correlation was found between the proportion of contaminated sediment and the number of chimneys: the more contaminated sediment, the fewer chimneys were constructed. The number of chimneys per surviving larva decreased with an increased proportion of contaminated sediment in parallel to increased larval mortality. We hypothesize that contents of these sediments negatively impact the larvae’s ability to survive at low oxygen concentrations due to impairments of essential behavioral and physiological processes. Full article

The need to regulate the non-exhaust particulate matter (PM) emissions from vehicles has been discussed worldwide due to the bad environmental impact and the toxicity to the human body. In-depth studies have been precisely conducted on the analysis of the non-exhaust particulate matters, in particular, the amount of tire, brake and road wear particles and their proportion in the atmosphere. In this study, the influence of tire and road wear particles (TRWP) on PM in the atmosphere was investigated with tire and PM samples. The PM samples suspended in the atmosphere were collected with a high-volume sampler equipped with a quartz filter. Additionally, polycyclic aromatic hydrocarbons (PAHs) and metal components in tire rubber were analyzed as markers by pyrolysis–gas chromatography/mass spectrometry (pyrolysis–GC/MS), GC/MS, and inductively coupled plasma/mass spectrometry (ICP/MS). More vinylcyclohexene was detected than dipentene in the markers measured in the samples of tires equipped with vehicles driving on the road, while more dipentene was measured in total suspended particles (TSP) samples. Among the PAHs in tire samples, pyrene exhibited the highest concentration. Benzo(b)fluoranthene showed the highest concentration in the TSP samples. Among the metals, the highest concentration was zinc in all tire samples and calcium in TSP samples. Full article

As a result of rising environmental awareness, vehicle-related emissions such as particulate matter are subject to increasing criticism. The air pollution in urban areas is especially linked to health risks. The connection between vehicle-related particle emissions and ambient air quality is highly complex. Therefore, a methodology is presented to evaluate the influence of different vehicle-related sources such as exhaust particles, brake wear and tire and road wear particles (TRWP) on ambient particulate matter (PM). In a first step, particle measurements were conducted based on field trials with an instrumented vehicle to determine the main influence parameters for each emission source. Afterwards, a simplified approach for a qualitative prediction of vehicle-related particle emissions is derived. In a next step, a virtual inner-city scenario is set up. This includes a vehicle simulation environment for predicting the local emission hot spots as well as a computational fluid dynamics model (CFD) to account for particle dispersion in the environment. This methodology allows for the investigation of emissions pathways from the point of generation up to the point of their emission potential. Full article

Traffic-related emissions are strongly criticised by the public because they contribute to climate change and are classified as hazardous to health. Combustion engine emissions have been regulated by limit values for almost three decades. There is currently no legal limit for non-exhaust emissions, which include tire wear particle emissions and resuspension. As a result, the percentage of total vehicle emissions has risen continuously. Some of the particles emitted can be assigned to the size classes of particulate matter (≤10 µm) and are therefore of particular relevance to human health. The literature describes a wide range of concepts for sampling and measuring tire wear particle emissions. Because of the limited number of studies, the mechanisms involved in on-road tests and their influence on the particle formation process, particle transport and the measuring ability can only be described incompletely. The aim of this study is to compare test bench and on-road tests and to assess the influence of selected parameters. The first part describes the processes of particle injection and particle distribution. Based on this, novel concepts for sampling and measurement in the laboratory and in the field are presented. The functionality and the mechanisms acting in each test environment are evaluated on the basis of selected test scenarios. For example, emissions from external sources, the condition of the road surface and the influence of the driver are identified as influencing factors. These analyzes are used to illustrate the complexity and limited reproducibility of on-road measurements, which must be taken into account for future regulations. Full article