Impacts of Tire Wear Emissions Compared to the Impacts of PM2.5 and PM10 on Humans

High Resolution Image Download MS PowerPoint Slide The discussion of potential adverse effects of particulate tire wear emissions on ecosystems and human health highlights the need for systematic evaluation of their sources, exposure pathways, and health impacts. Global urbanization may increase exposure to tire and road wear particles (TRWPs) and tire-related chemicals, especially in high-traffic areas. This literature review examines current knowledge on human exposure to TRWPs and tire-related chemicals and explores whether TRWPs pose a distinctive risk compared with airborne particulate matter (PM). Analytical challenges persist in identifying airborne TRWPs, as most research focuses on tire wear particles (TWPs) alone, due to difficulties in defining mass ratios within the TRWP aggregate. TWPs constitute <5 wt % of ambient PM2.5 and PM10; however, inconsistent analytical methodologies hinder a conclusive exposure assessment. Actual data on human exposure to TWPs or TRWPs are scarce. Tire-related chemicals have been found in human body fluids, but their exposure pathways are unclear. Toxicological data mainly derive from in vitro studies with few harmonized designs. Comparative research suggests that TRWPs are not more toxic than other PM fractions. This review emphasizes the need for harmonized methods, global and regional exposure characterization, and identification of TRWP exposure pathways for humans to address potential health implications more accurately.