From Streets to Seats: Assessment of Tire Wear Particles and Tire Additive Chemicals in Australian Urban Dust

Tire wear particles (TWPs) and tire additive chemicals (TACs) are increasingly being recognized as important nonexhaust traffic emissions, yet their atmospheric transport and accumulation in residential environments remain poorly characterized. In this study, TWPs and TACs were quantified in urban dust collected from 30 outdoor residential balconies across the Brisbane metropolitan region, Australia, using pyrolysis gas chromatography–mass spectrometry (Pyr-GC/MS) and liquid chromatography-tandem mass spectrometry (LC-MS/MS). TWP deposition rates ranged from <0.0006 to 4.1 mg/m 2 /day (median 0.3 mg/m 2 /day), while total TAC surface loadings (∑TACs) ranged from <0.01 to 316 ng/m 2 /day (median 69 ng/m 2 /day). Elevated TWP deposition was primarily associated with low wind speed. TAC concentrations showed weaker coupling with particle mass, with TAC/TWP ratios spanning more than 2 orders of magnitude across sites. Near-Central Business District (CBD) balconies showed markedly elevated TAC/TWP ratios (median 333 ng/mg vs 101 ng/mg, within 5 km from the CBD), indicating chemical enrichment relative to particle mass and suggesting atmospheric transformation. 6PPD-quinone ( N -(1,3-dimethylbutyl)- N ′-phenyl- p -phenylenediamine-quinone) was detected at 23 of the 30 sampled balconies, demonstrating its widespread occurrence in outdoor residential dust. These findings indicate that residential balconies act as sinks for airborne TWPs and TACs. Importantly, TAC concentrations do not necessarily scale with total TWP, suggesting chemical enrichment relative to particle mass driven by atmospheric processing and redistribution during airborne transport. This study provides the first quantitative evidence of TWPs and TACs in Australian urban dust and highlights the need to jointly consider particulate and chemical components when evaluating urban tire-related pollution and potential human exposure pathways.