Health impact of tire wear particles remains inconclusive

Geneva, Switzerland – The final installment of a three-part scientific State of Knowledge (SoK) paper series on tire wear emissions concludes that, while the understanding of tire wear emissions has advanced, current data to quantify human health impacts attributable to tire wear emissions remains inconclusive.

The review finds that differences in sampling approaches, detection techniques and analytical methodologies limit reliable comparison across studies and prevent robust risk assessment. In addition, based on the peer-reviewed literature studied, tire wear particles constitute only a small part of the overall airborne particulate matter, with similar or less potent effects compared to other particulate matter fractions.

Supported by the Tire Industry Project (TIP)—part of the World Business Council for Sustainable Development (WBCSD)—the SoK series represent the most comprehensive review of global science on tire wear emissions to date, analyzing more than 850 peer-reviewed scientific publications.

Independently authored by Kathrin Müller, Julie Panko, Kenny M. Unice, and Dr. Stephan Wagner, the paper “Impacts of Tire Wear Emissions Compared to the Impacts of PM2.5 and PM10 on Humans” reviews existing scientific knowledge on human exposure to tire and road wear particles (TRWP) and tire-related chemicals, concluding that:

Tire wear particles make up only a small share of airborne particulate matter, typically less than 5% of PM 2.5 and PM 10 in urban environments.
Toxicological studies to date do not show TRWP to be more harmful than general ambient particulate matter. Available in vivo and in vitro data indicate effects that are similar to or less potent than other airborne particle types.
Despite growing interest, scientific evidence on human exposure to TRWP remains limited and inconclusive. Chemicals that are used in tire manufacturing are detectable in human body fluids, but their sources and exposure pathways have not been clearly linked specifically to tires, as many of these chemicals are used in a range of other applications.
A major barrier to drawing firm conclusions is the lack of consistent global methods for sampling, analyzing, and characterizing tire wear emissions. Variability in methodologies across studies limits meaningful comparison and robust exposure or risk assessment.

Call for coordinated research efforts

As a result, the authors of the papers call for greater harmonization of research methodologies to improve identification, measurement and attribution of tire wear emissions. This need for coordinated efforts aligns with the conclusions of SoK Papers 1 and 2, which were published in 2025 and examined the characterization and quantification of tire wear emissions and their potential impacts on the environment.

The authors recommend that future research should identify potential exposure pathways and examine relevant health outcomes—including potential chronic effects—under realistic exposure conditions covering urban and suburban populations across different regions worldwide.

Dr. Stephan Wagner, one of the leading researchers of Paper 3, said: “Tire wear emissions are a complex topic that we still only partly understand, especially in relation to human health. While research has advanced our understanding of TRWP, the current data simply isn’t robust enough to quantify any potential health risks specifically linked to tire wear. Looking forward, cross-stakeholder collaboration is fundamental to making rapid progress. By aligning methods, sharing data, and focusing on real-world studies, we can build a stronger, more consistent evidence base to inform future decisions.”