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In northern countries, the climate, and consequently the use of studded tyres and winter traction sanding, causes accumulation of road dust over winter and spring, resulting in high PM 10 concentrations during springtime dusting events. To quantify the dust at the road surface, a method-the wet dust sampler (WDS)was developed allowing repeatable sampling also under wet and snowy conditions. The principle of operation is flushing high-pressurised water over a defined surface area and transferring the dust laden water into a container for further analyses. The WDS has been used for some time and is presented in detail to the international scientific community as reported by Jonsson et al. (2008) and Gustafsson et al. (2019), and in this paper, the latest version is presented together with an evaluation of its performance. To evaluate the WDS, the ejected water amount was measured, as well as water losses in different parts of the sampling system, together with indicative dust measurement using turbidity as a proxy for dust concentration. The results show that the WDS, when accounting for all losses, have a predictable and repeatable water performance, with no impact on performance based on the variety of asphalt surface types included in this study, given undamaged surfaces. The largest loss was found to be water retained on the surface, and the dust measurements imply that this might not have as large impact on the sampled dust as could be expected. A theoretical particle mass balance shows small particle losses, while field measurements show higher losses. Several tests are suggested to validate and improve on the mass balances. Finally, the WDS is found to perform well and is able to contribute to further knowledge regarding road dust implications for air pollution.

Tyre and road wear particles (TRWP) are an important microplastics contributor to the environment, although direct observations along suggested pathways are virtually absent. There are concerns for both human health and ecosystems from TRWP exposure and leached chemicals. Due to great analytical challenges in detection and characterization, almost nothing is known about the physicochemical characteristics, occurrence, fate and transport of TRWP in the environment. Diverse tyre types exist for different seasons and vehicle profiles, and their formulations are undisclosed proprietary information.Here we show TRWP dispersion in marine sediments, and a direct link between tyre formulation, tread hardness and TRWP emissions. Softer tyres with higher natural rubber and carbon black content generate higher particle wear. Sediment TRWP dominates the microplastics assemblage close to the city, while showing a much more steeply reducing concentration gradient with distance from the source, suggesting different transport behaviour compared to lower density microplastics. This implies that urbanized coastal ecosystems are impacted by the accumulating TRWP, with consequences for sediment ecosystems.One-sentence summaryTyre and road wear particles—The link between tyre formulation, emissions and their spread in the marine environment.

Tires, bitumen, and road markings are important sources of traffic-derived carbonaceous wear particles and microplastic (MP) pollution. In this study, we further developed a machine-learning algorithm coupled to an automated scanning electron microscopy/energy dispersive X-ray spectroscopy (SEM/EDX) analytical approach to classify and quantify the relative number of the following subclasses contained in environmental road dust: tire wear particles (TWP), bitumen wear particles (BiWP), road markings, reflecting glass beads, metallics, minerals, and biogenic/organics. The method is non-destructive, rapid, repeatable, and enables information about the size, shape, and elemental composition of particles 2–125 µm. The results showed that the method enabled differentiation between TWP and BiWP for particles > 20 µm with satisfying results. Furthermore, the relative number concentration of the subclasses was similar in both analyzed size fractions (2–20 µm and 20–125 µm), with minerals as the most dominant subclass (2–20 µm x̄ = 78%, 20–125 µm x̄ = 74%) followed by tire and bitumen wear particles, TBiWP, (2–20 µm x̄ = 19%, 20–125 µm x̄ = 22%). Road marking wear, glass beads, and metal wear contributed to x̄ = 1%, x̄ = 0.1%, and x̄ = 1% in the 2–20-µm fraction and to x̄ = 0.5%, x̄ = 0.2%, and x̄ = 0.4% in the 20–125-µm fraction. The present results show that road dust appreciably consists of TWP and BiWP within both the coarse and the fine size fraction. The study delivers quantitative evidence of the importance of tires, bitumen, road marking, and glass beads besides minerals and metals to wear particles and MP pollution in traffic environments based on environmental (real-world) samples