Measurements of brake and tire wear particulate emissions from light-duty vehicles under WLTC driving conditions

Non-exhaust particulate emissions from road traffic are emerging as the dominant source of vehicular particle pollution as tailpipe emissions continue to decline. This study presents a comprehensive experimental methodology for quantifying brake and tire wear particulate emissions from light-duty vehicles under controlled laboratory conditions. Three vehicles representative of the European fleet, a Euro 5 light commercial vehicle and two Euro 6 hybrid passenger cars, were tested over the European type-approval driving cycle, carried out on chassis dynamometer roller bench. Two dedicated collection systems were developed: a sealed brake chamber tailored to each vehicle's front-right assembly, and a semi-enclosed chamber designed to capture tire wear particles during vehicle driving. Both systems were connected to an integrated sampling line enabling the measurement of PM10, PM2.5, total particulate mass, and particle number and size distributions. Results highlight the strong influence of vehicle mass, braking strategy, and driving conditions on emission levels. The full-hybrid passenger car exhibited the lowest brake wear emissions due to extensive regenerative braking. Tire wear emissions were consistently higher during the low and medium-speed phases of the WLTC, reflecting the dominant role of accelerations. The methodology and results provide robust, representative emission factors for modern light-duty vehicles, supporting the refinement of non-exhaust particulate inventories and the development of future regulatory frameworks.