Airborne Tire and Road Wear Particles (TRWP): A Comprehensive Study of TRWP Emissions, Analytical Characterization, and Environmental Impacts

The progressive reduction of exhaust sources of particulate matter emissions in the transportation sector has shifted the scientific attention to their non-exhaust counterparts. Among these, tire and road wear particles (TRWPs) constitute one of the largest contributors to airborne and deposited microplastics. This thesis presents a comprehensive study of airborne TRWP emissions, their environmental fate, physical and chemical characterization, and possible environmental and health implications. Given work also recommends a suite of mitigation measures, that are suggested to be applied in combination. The thesis work consolidates current state-of-art knowledge on TRWPs generation mechanisms and distribution, highlighting the variability in TRWPs size, morphology and chemical composition. Analytical techniques such as Scanning Electron Microscopy combined with Energy Dispersive X-ray Spectroscopy (SEM-EDX), Fourier Transform Infrared Spectrometry (FTIR), and pyrolysis gas chromatography-mass spectrometry (Py-GC/MS) are critically reviewed. Environmental investigation of TRWPs demonstrates that they are widely dispersed and found in air, in road dusts, different aquatic systems, soils, and sediments, with airborne TRWPs being considered as a particular concern due the human inhalation exposure. The findings emphasise that TRWPs are one of the most significant sources of PM and MP pollution with increasing relative importance. In order to properly address its dominance across environmental compartments, a coordinated scientific, regulatory, and technological action is essential. By identifying research and data gaps and examining mitigation measures, this thesis work contributes to advancing the academic understanding of TRWPs aimed at reducing the environmental footprint of transportation.