Tracer-Gas-Integrated Measurements of Brake-Wear Particulate Matter Emissions from Heavy-Duty Vehicles

Automotive brake-wear emissions are increasingly important in on-road particulate matter (PM) emission inventory. Previous studies reported a high level of PM emissions from the friction materials of light/medium-duty vehicles, but there are few data available from heavy-duty (HD) vehicles equipped...

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Bibliographic Details
Published in:Environmental science & technology 2023-10, Vol.57 (42), p.15968-15978
Main Authors: Lee, Eon S., Sahay, Keshav, O’Neil, Edward, Biswas, Subhasis, Dzhema, Inna, Huang, Shiou-Mei, Lin, Peng, Chang, Ming-Chih Oliver, Huai, Tao
Format: Article
Language:English
Subjects:
Automobiles
Coefficient of variation
Drum brakes
Emission analysis
Emission inventories
Emission measurements
Emissions
Emissions testing
Exhaust emission
Exhaust pipes
Heavy vehicles
Occurrence, Fate, and Transport of Contaminants in Indoor Air and Atmosphere
Particulate emissions
Particulate matter
Tracer gas
Vehicles
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Summary:Automotive brake-wear emissions are increasingly important in on-road particulate matter (PM) emission inventory. Previous studies reported a high level of PM emissions from the friction materials of light/medium-duty vehicles, but there are few data available from heavy-duty (HD) vehicles equipped with drum brakes despite their popularity (∼85% in HD vehicle fleet). This study developed a novel tracer-gas-integrated method for brake-wear PM emission measurements and evaluated four HD vehicles on a chassis dynamometer that complied with regulatory exhaust emission testing requirements. Three class-6 vehicles with a similar test weight demonstrated repeatability, with the coefficient of variation in the range of 9–36%. Braking events increased PM concentrations by 3 orders of magnitude above the background level. Resuspension of brake-wear PM also occurred during acceleration and contributed to 8–31% of the total PM2.5 mass. The class-6 vehicles had PM2.5 emissions from a single brake (0.7–1.5 mg/km/brake), generally similar to the level of tail-pipe exhaust PM emissions (0.7–1.5 mg/km/vehicle) of each vehicle. A class-8 vehicle exhibited brake-wear PM2.5 emissions (2.4–3.4 mg/km/brake) significantly higher than the tail-pipe exhaust PM emissions (∼1.3 mg/km/vehicle). This article reports an exceptionally high level of brake-wear PM emissions measured directly from the drum brakes of HD vehicles.
ISSN:0013-936X
1520-5851
DOI:10.1021/acs.est.3c03673