Identifying Mass Spectral Markers for Tire Wear Particles

XING WANG, Arthur W. H. Chan, Greg J. Evans, University of Toronto

     Abstract Number: 100
     Working Group: Urban Aerosols

Abstract
Non-exhaust particles are a major source of primary particulate matter emission from traffic, and their contribution is growing. These particles arise from the wear of brakes, tires, and road surfaces, are unregulated in North America, and now estimated to exceed exhaust particulate matter emissions in many jurisdictions. Apportioning the contribution of non-exhaust emissions to ambient particulate matter concentrations is challenging due to the lack of appropriate tracers for each non-exhaust component. Metal markers have previously been used based on the material composition and scaling factors, but this approach is limited for tire wear particles since markers like Zn can originate from other sources. Here, we develop methods to characterize tire wear particles using online aerosol mass spectrometry and offline pyrolysis-gas chromatography-mass spectrometry, with the aim of identifying robust mass spectral markers to estimate the contribution of tire wear particles to ambient particulate matter. We analyzed submicron tire wear particles generated using a diamond burr sander attached to Dremel rotary tool and cryogenically-milled tire tread particles. We observed hydrocarbon-like organic aerosol and ions corresponding to tire tread additives. This combination of ions may be useful as markers to resolve the contribution of tire wear particles in near roadway environments.