Metal contents and size distributions of brake and tire wear particles dispersed in the near-road environment

López, Benjamín; Wang, Xiaoliang; Chen, L.-W. Antony; Ma, Tianyi; Mendez-Jimenez, David; Cobb, Ling Cui; Frederickson, Chas; Fang, Ting; Hwang, Brian; Shiraiwa, Manabu; Park, Minhan; Park, Kihong; Yao, Qi; Yoon, Seungju; Jung, Heejung

doi:10.1016/j.scitotenv.2023.163561

Cited by 13 publications

(6 citation statements)

References 28 publications

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“…BMPO–OH shows a strong positive correlation with barium ( p < 0.01). Ba is the third most abundant metal in NAO BWPs (Figure B) and is widely used as a tracer for brake wear emissions. ,,, Liu et al (2022) also found a strong correlation (Spearman correlation coefficient r = 0.96) between Ba and calculated ROS formation in the epithelial lining fluid. We conducted control experiments by using similar concentrations of barium sulfate, which is the most common space filler in brake pads, to test if Ba 2+ can generate ·OH.…”

Section: Resultsmentioning

confidence: 96%

“…The dominance of Fe may partly be explained by the fact that rotor discs are made of gray cast iron . Many studies have reported Fe, Cu, Zn, Zr, Sn, and Sb as abundant heavy metals from BWPs. , All types of BWPs exhibit substantial concentrations of OC and EC with >10 μg mg –1 , with both ceramic and semimetallic BWPs showing higher values of EC compared to NAO BWPs. While the total reported carbonaceous fraction of BWPs can be highly variable (5.07–75.4%), , OC and EC are likely the result of the thermal decomposition of carbonaceous constituents such as the phenolic resin and aramid fiber commonly used as binders and reinforcement materials, respectively in brake pads. ,− Interestingly, total carbon in NAO BWPs is tightly anticorrelated with total metals (sum of all metals; Figure C).…”

Section: Resultsmentioning

confidence: 99%

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Aqueous OH Radical Production by Brake Wear Particles

Fang,

Kapur,

Edwards

et al. 2024

Environ. Sci. Technol. Lett.

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Particulate matter (PM) emitted from road traffic causes adverse health effects upon inhalation and respiratory deposition. Non-exhaust emissions will eventually become the dominant source of traffic PM upon transition to electric vehicles; however, non-tailpipe PM is currently unregulated as its health impacts are still unclear. In this study, we generated brake wear particles (BWPs) with non-asbestos organic, ceramic, and semimetallic brake pads using custom dynamometers and measured aqueous-phase formation of reactive oxygen species (ROS). We found that BWPs do not contain environmentally persistent free radicals (EPFRs), and all types of BWPs generate exclusively ·OH radicals in water. BWPs generated by ceramic and semimetallic brakes during heavier braking lead to higher ·OH yields compared to gentle braking conditions, suggesting higher ·OH formation potential from ultrafine BWPs. Chemical characterization reveals that organic and elemental carbon correlated positively with ·OH formation while exhibiting negative correlations with abundant metals including Fe and Mn. We suggest that the source of ·OH is thermal decomposition of organic hydroperoxides derived from phenolic resin. PM oxidative potential quantified with the dithiothreitol (DTT) assay exhibited a positive correlation with the ·OH yield. These results provide critical insights into the toxicity and adverse health effects of BWPs.

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Section: Resultsmentioning

confidence: 96%

Section: Resultsmentioning

confidence: 99%

Aqueous OH Radical Production by Brake Wear Particles

Fang,

Kapur,

Edwards

et al. 2024

Environ. Sci. Technol. Lett.

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“…In addition, traffic sources commonly include a mixture of tailpipe emissions from gasoline/diesel engines, brake wear, and road dust [ 34 , 35 ]. The high loadings of Sb, Ba, and Cu may be vehicle-derived metals from brake/tire wear, and Zn may be from tire wear and lubricating oil [ 23 , 36 , 37 , 38 ]. High loadings of crustal elements, including Ca and Fe, suggest that this factor included suspended road/urban dust.…”

Section: Resultsmentioning

confidence: 99%

Reduction of Outdoor and Indoor PM2.5 Source Contributions via Portable Air Filtration Systems in a Senior Residential Facility in Detroit, Michigan

Klaver,

Crane,

Ziemba

et al. 2023

Toxics

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Background: The Reducing Air Pollution in Detroit Intervention Study (RAPIDS) was designed to evaluate cardiovascular health benefits and personal fine particulate matter (particulate matter < 2.5 μm in diameter, PM2.5) exposure reductions via portable air filtration units (PAFs) among older adults in Detroit, Michigan. This double-blind randomized crossover intervention study has shown that, compared to sham, air filtration for 3 days decreased 3-day average brachial systolic blood pressure by 3.2 mmHg. The results also showed that commercially available HEPA-type and true HEPA PAFs mitigated median indoor PM2.5 concentrations by 58% and 65%, respectively. However, to our knowledge, no health intervention study in which a significant positive health effect was observed has also evaluated how outdoor and indoor PM2.5 sources impacted the subjects. With that in mind, detailed characterization of outdoor and indoor PM2.5 samples collected during this study and a source apportionment analysis of those samples using a positive matrix factorization model were completed. The aims of this most recent work were to characterize the indoor and outdoor sources of the PM2.5 this community was exposed to and to assess how effectively commercially available HEPA-type and true HEPA PAFs were able to reduce indoor and outdoor PM2.5 source contributions. Methods: Approximately 24 h daily indoor and outdoor PM2.5 samples were collected on Teflon and Quartz filters from the apartments of 40 study subjects during each 3-day intervention period. These filters were analyzed for mass, carbon, and trace elements. Environmental Protection Agency Positive Matrix Factorization (PMF) 5.0 was utilized to determine major emission sources that contributed to the outdoor and indoor PM2.5 levels during this study. Results: The major sources of outdoor PM2.5 were secondary aerosols (28%), traffic/urban dust (24%), iron/steel industries (15%), sewage/municipal incineration (10%), and oil combustion/refinery (6%). The major sources of indoor PM2.5 were organic compounds (45%), traffic + sewage/municipal incineration (14%), secondary aerosols (13%), smoking (7%), and urban dust (2%). Infiltration of outdoor PM2.5 for sham, HEPA-type, and true HEPA air filtration was 79 ± 24%, 61 ± 32%, and 51 ± 34%, respectively. Conclusions: The results from our study showed that intervention with PAFs was able to significantly decrease indoor PM2.5 derived from outdoor and indoor PM2.5 sources. The PAFs were also able to significantly reduce the infiltration of outdoor PM2.5. The results of this study provide insights into what types of major PM2.5 sources this community is exposed to and what degree of air quality and systolic blood pressure improvements are possible through the use of commercially available PAFs in a real-world setting.

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“…Brake-wear PM emissions contain trace elements such as zinc (Zn), manganese (Mn), iron (Fe), copper (Cu), and nickel (Ni). – Although few toxicology studies directly investigated these metal elements in brake-wear PM emissions, previous toxicology studies identified Zn, Mn, Fe, and Cu to induce proinflammatory responses in the lungs of mice, rats, and humans. , In addition, an in vitro study showed that brake-wear PM emissions containing Fe, Cu, and Mn increase cytotoxicity related to oxidative stress and proinflammatory responses . Metal-enriched anthropogenic PM containing Zn and Ni is known to cause pulmonary injury, inflammation, negative systemic extrapulmonary effects, and cardiotoxicity .…”

Section: Introductionmentioning

confidence: 99%

“…CARB has also identified brake-wear as an important source of particulate matter (PM) emissions that are projected to increase in near future . CARB has investigated brake-wear emissions in multiple testing platforms such as near-road, brake dynamometer, and chassis dynamometer in a Running Loss Sealed Housing for Evaporative Emission Determination (RL-SHED) chamber. – The current heavy-duty (HD) vehicle chassis dynamometer study complements the ongoing efforts of CARB and reports brake-wear PM emissions measured from the drum brakes of HD vehicles.…”

Section: Introductionmentioning

confidence: 99%

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

Lee,

Sahay,

O’Neil

et al. 2023

Environ. Sci. Technol.

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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 PM 2.5 mass. The class-6 vehicles had PM 2.5 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 PM 2.5 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.

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Metal contents and size distributions of brake and tire wear particles dispersed in the near-road environment

Cited by 13 publications

References 28 publications

Aqueous OH Radical Production by Brake Wear Particles

Aqueous OH Radical Production by Brake Wear Particles

Reduction of Outdoor and Indoor PM2.5 Source Contributions via Portable Air Filtration Systems in a Senior Residential Facility in Detroit, Michigan

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

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