In an era where environmental pollution has gained unprecedented attention, a new study published in Microplastics & Nanoplastics is drawing focus to a surprisingly pervasive but often overlooked pollutant: tire particles embedded in road soils. The research, conducted by Kundel, Wiget, Fliessbach, and their colleagues, systematically unveils the concentration and distribution of tire-derived contaminants across multiple Swiss cantons. This pioneering work not only highlights the extent to which vehicular traffic impacts terrestrial ecosystems but also breaks new ground in understanding the chemical and physical properties of tire particles as emerging environmental hazards.
Tire wear particles (TWPs) have long been recognized as a significant source of microplastics and polymeric pollutants. Released during routine tire-road interactions, these particles are composed of synthetic rubbers, fillers, and a cocktail of chemical additives. Unlike exhaust emissions, which have seen substantial regulatory reductions over the past decades, tire particles persistently contribute to non-exhaust particulate matter, infiltrating soils, waterways, and ultimately the food chain. The study by Kundel et al. provides the first comprehensive quantification of such particles embedded in roadside soils, offering a snapshot of the “invisible” contamination making its way into terrestrial environments.
Using advanced analytical techniques, the researchers collected and analyzed soil samples from diverse cantonal locations, reflecting a range of traffic densities and environmental conditions. Their approach incorporated pyrolysis-gas chromatography-mass spectrometry (Py-GC/MS) to chemically fingerprint the polymeric components, isolating tire-derived compounds from natural soil organic matter. This methodology allowed for a high degree of specificity and sensitivity, overcoming the challenges that have historically hampered detection of tire particles due to their heterogeneous and chemically complex nature.
One of the study’s most striking findings is the spatial variability of tire particle concentrations; soils adjacent to high-traffic roadways exhibited significantly elevated levels, often surpassing natural background concentrations by orders of magnitude. Remarkably, even less trafficked rural roads showed measurable contamination, suggesting widespread dispersion mechanisms that allow tire particles to migrate beyond immediate roadside areas. These results underscore the urgency of addressing non-exhaust sources of pollution in environmental regulatory frameworks, which until now have predominantly focused on airborne particulates and chemical runoff.
Beyond mere quantification, the study delves into the physicochemical characteristics of the tire particles, illuminating their size distribution, morphology, and chemical persistence. Most particles detected fell within the micrometer range, with a notable fraction descending into the nanoplastic scale. Given the growing evidence of nanoplastics’ enhanced bioavailability and potential toxicity, this finding raises critical questions about the long-term environmental and human health implications of chronic exposure to tire wear residues in soils.
The presence of these particles in soil matrices introduces complex contamination dynamics. Unlike aquatic microplastics, which are often suspended or transported over large distances, tire particles in soils interact intimately with mineral surfaces, organic compounds, and microbial communities. The study indicates that tire-derived chemicals may leach into surrounding soils, altering microbial ecology, nutrient cycling, and soil structure. Such alterations could cascade into broader ecosystem disturbances, affecting plant health and soil fauna, potentially reshaping terrestrial habitat quality in high-traffic regions.
Moreover, the persistence of tire particles stems from their synthetic rubber bases, which degrade sluggishly in subsurface environments. Additives such as carbon black, plasticizers, and vulcanizing agents further complicate biodegradation processes, leading to the acceleration of chemical recalcitrance and bioaccumulation risks. Kundel et al. emphasize the need for further ecotoxicological studies to unravel how these constituents interact with biotic components at various trophic levels. Early evidence hints at possible adverse effects on earthworms and soil invertebrates, organisms central to soil health and fertility.
The study also evaluates seasonal and meteorological influences on particle distribution. Precipitation patterns were found to play a critical role in mobilizing tire particles from road surfaces into adjacent soils. During rain events, runoff facilitates the transport of these fine particulates, embedding them deeper into the soil column or even washing them into aquatic systems. Temperature fluctuations impact the physical brittleness of tires, potentially affecting particle generation rates over time. These nuanced insights provide valuable parameters for modeling the environmental fate of tire wear debris under changing climate conditions.
Traffic volume and vehicular type were additional variables scrutinized in the analysis. Heavy vehicles, such as trucks and buses, contribute disproportionately to tire wear due to greater load stresses and braking intensity. The varying compositions of tires—ranging from passenger car tires primarily composed of styrene-butadiene rubber to more specialized truck tires with added durability compounds—also influence the chemical signature of emitted particles. This heterogeneity complicates remediation efforts, emphasizing the necessity for tailored mitigation strategies.
One of the forward-looking aspects of the research is its implications for urban planning and infrastructure design. The data implicate roadside vegetation strips and buffer zones as potential sinks or filters for tire particles, suggesting that strategically engineered green areas could mitigate contaminant dispersion. However, the long-term retention of tire particles in these areas may introduce new environmental risks, necessitating a balanced approach between pollution control and ecological resilience.
Technological innovations stemming from this research could transform monitoring practices. The application of Py-GC/MS, combined with machine learning-assisted spectral analysis, offers a robust toolkit for ongoing surveillance of tire particle pollution. These advancements could facilitate rapid assessment of pollution hotspots, guiding policymakers and environmental managers in deploying targeted interventions. Additionally, the quantified correlation between traffic metrics and soil contamination provides a predictive framework for risk assessment in urban and rural settings alike.
From a societal perspective, the findings spotlight the hidden costs of mobility and the urgent need to rethink sustainable transportation solutions. While electrification and emission control strategies have gained momentum, non-exhaust particulate matter such as tire wear remains a blind spot in environmental policy. Kundel and colleagues advocate for integrated approaches that encompass tire design improvements, road surface engineering, and behavioral changes to reduce tire particle generation, thereby addressing this insidious pollutant comprehensively.
In conclusion, this landmark study magnifies the scope of microplastic pollution by exposing the pervasive presence of tire particles in Swiss road soils and bringing attention to their multifaceted environmental impacts. It sets a new benchmark for the detection, quantification, and understanding of tire-derived pollutants, galvanizing the scientific community to further investigate and mitigate this emerging threat. As urbanization and vehicle use continue to expand globally, such research underscores the imperative to incorporate tire particle pollution into the broader narrative of environmental contamination and public health protection.
Subject of Research: Tire particle concentrations in road soils and their environmental implications.
Article Title: Tracks of travel: unveiling tire particle concentrations in Swiss cantonal road soils.
Article References:
Kundel, D., Wiget, A., Fliessbach, A. et al. Tracks of travel: unveiling tire particle concentrations in Swiss cantonal road soils. Micropl.&Nanopl. 5, 6 (2025). https://doi.org/10.1186/s43591-025-00112-1
Image Credits: AI Generated
