THEORETICAL FOUNDATIONS OF TIRE AND BRAKE WEAR PARTICLE FORMATION DURING URBAN BUS OPERATION
Keywords:
Non-exhaust emissions; tire wear particles; brake wear particles; urban buses; particulate matter; microplasticsAbstract
Urban bus fleets emit substantial non-exhaust particulate matter (PM), driven by heavy axle loads and intensive braking cycles. This review synthesizes the mechanistic understanding of particle formation from tires and brakes under urban bus duty cycles, including core generation mechanisms, particle characteristics, and key emission factors. We discuss tire wear processes (abrasion, stick–slip, tread evaporation) and brake wear processes (frictional heating, tribochemistry), highlighting how high load and low-speed bus operation affects these. Measured emissions for heavy vehicles are summarized. Implications for particle fate, health impacts, and mitigation are addressed
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