A polymer-based quantification of Tire wear particles (TWP) in atmospheric deposition samples using pyrolysis-gas chromatography-mass spectrometry (Py-GC-MS)
Tire wear particles (TWPs) constitute a significant source of environmental microplastics and airborne particulate matter (PM2.5 and PM10). Global per capita emissions range from 0.23 to 4.7 kg per year, with an average of 0.81 kg per year.1 TWPs contribute 5–10% of oceanic plastic pollution and 3–7% of ambient PM2.5, exacerbating the global health burden of air pollution.1 In addition to representing the primary anthropogenic source of zinc (Zn), TWPs contain over 200 toxic organic compounds in the environment.2 Given their pervasive distribution, accurate quantification of TWPs across diverse geographical regions and understanding their transport pathways through air and water are critical for assessing environmental and public health risks. However, estimating TWP emissions remains analytically challenging due to variations in tire composition across different manufacturers, varying usage conditions, and varying tire ages.
Traditional analytical methods, including Fourier-transform infrared (FTIR) spectroscopy, elemental analysis, and single-marker detection through gas chromatography-mass spectrometry (GC-MS) or high-performance liquid chromatography (HPLC), encounter limitations in consistently quantifying tire wear particles (TWPs) due to matrix interferences. In response to these challenges, we have developed an integrated pyrolysis gas chromatography-mass spectrometry (Py-GC-MS) method that quantifies the total polymer content of TWPs, rather than depending on individual markers. This innovative approach incorporates optimized sample preparation techniques to minimize interference from co-occurring environmental contaminants. By thoroughly analyzing both primary and secondary pyrolysis products of tire rubber, our method facilitates a more precise and comprehensive quantification of TWPs.
Furthermore, we applied this methodology to atmospheric deposition samples collected from different locations in Switzerland. The data, combined with land use statistics, will estimate the annual atmospheric input of TWP into these areas. These findings will provide a basis for assessing the environmental risks associated with TWPs and their derived chemicals.