Fresh tire wear particles from moving vehicles: Dispersion dynamics, exposure, and prevention strategy

Tire Wear Particles (TWPs) have emerged as a significant source of non-exhaust emissions, posing potential exposure risks due to increased vehicle ownership and the advent of new energy vehicles. However, the dispersion and flow dynamics of fresh TWPs remain largely unexplored. Here, we used a finite element aerodynamic simulation model to investigate the distribution of fresh TWPs from a moving vehicle and to assess human respiratory exposure near the vehicle. In addition, actual on-road particle level measurements were performed to qualitatively validate the results obtained from our model while developing a laboratory-scale emission reduction solution. Conservative data show that fresh TWPs (of 0.1–10 μm diameter) disperse up to 3.2 m wide and 2.2 m high, with minimal influence of particle size. At 1–2 m from the side of the vehicle driven at 60 km/h, the maximum concentration was found at a height of 0.8 m, reaching 5.0 μg/m3, demonstrating a significant exposure of children and adolescents. The emission reduction solution designed to mitigate the exposure risk (i.e., a collection channel mounted near the wheel cover) was shown to effectively reduce fresh TWP emissions, achieving a capture rate of >40 % at high speeds. Overall, the results obtained underscore the potential health issues associated with TWPs in urban areas, but also the ability to reduce exposure, provided that appropriate mitigation strategies are adopted.