Microplastic and tyre wear particles at a highway: a case study from Norway

<title>Abstract</title> This study explores the presence of microplastics (MPs) including tyre wear particles (TWPs) in three environmental compartments-air, road runoff, and road dust-collected near a heavily trafficked highway in southern Norway. Using µFTIR and Py-GC/MS, we characterised the polymer composition, particle sizes, and estimated mass across matrices. Polypropylene dominated in road runoff and road dust, while polyester and polyamide were most frequent in air samples. MP concentrations were highest in road dust [567–4250 counts/m ² or 31–291 µg/m²], followed by road runoff [65–598 counts/L or 0.4–11.7µg/L] and air [5–12 counts/day or 0.16–0.22 µg/day]. TWP concentration was below the detection limit in the air samples, while for road runoff it was in the range 281–1470 µg/L, and for road dust it was 33500–178777 µg/m ² . Although meteorological parameters such as wind speed and precipitation must influence airborne MP capture, no strong correlations were identified. The results suggest that road runoff and road dust better reflected local traffic-related emissions, while air samples were more affected by atmospheric transport. This highlights the need to consider environmental context and sampling strategy when assessing airborne MP pollution. Our findings emphasize the importance of multi-matrix approaches to understand the distribution and behaviour of traffic-derived MPs in complex environments.