Occurrence of tyre-derived particles in size-segregated aerosol in the urban area of Venice

Benzothiazoles (BTHs), commonly used in various industrial applications, have emerged as significant contaminants due to their widespread usage and potential adverse effects on ecosystems and human health. The aim of this study is to quantify and, for the first time, to characterize the particle size distribution of eight BTHs across twelve fractions of atmospheric aerosol representative of the urban boundary layer. Samples were collected from August to October 2023 in the urban area of Venice, located in the Po Valley, known for its poor air quality. Instrumental analysis was achieved via an UHPLC system coupled with a triple quadrupole mass spectrometer. All target compounds were present in the samples analyzed and most of them tended to distribute mainly in the fine fraction of aerosol (<1.8 μm). An exception is given by BTH-SO3H, which presents a bimodal distribution with maxima centered in the coarse fraction; this may imply a different source compared to other BTHs. BTH-SH is the most abundant benzothiazole derivative, suggesting tyre debris as the main source since it is the main compound used in vulcanizing accelerators in rubber manufacture. Given its mutagenic properties, its high relative abundance could be of concern for human health. Results of this work provide valuable insights into the distribution of BTHs in urban aerosols, laying the groundwork for future research aimed at better understanding their sources and environmental pathways, fate and impacts.