Oxidative potential of on-road fine particulate matter (PM 2.5 ) measured on major freeways of Los Angeles, CA, and a 10-year comparison with earlier roadside studies

Shirmohammadi, Farimah; Wang, Dongbin; Hasheminassab, Sina; Verma, Vishal; Schauer, James J.; Shafer, Martin M.; Sioutas, Constantinos

doi:10.1016/j.atmosenv.2016.10.042

Cited by 64 publications

(46 citation statements)

References 75 publications

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“…A direct comparison of the ROS activity of the fog and aerosol samples collected in this study with those of ambient aerosol previously reported by other studies is associated with some uncertainties due mainly to the different size range of the particles collected and the fact that the ROS activity appears to be strongly particle-size-dependent (Sioutas et al, 2005;Saffari et al, 2014). Nonetheless these results point to possible health effects associated with PM exposure during fog episodes in the Po Valley, the toxicity of which are comparable or, in many cases, higher than that of the highly toxic traffic-related PM.…”

Section: Discussionmentioning

confidence: 58%

Enhanced toxicity of aerosol in fog conditions in the Po Valley, Italy

et al. 2017

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Abstract. While numerous studies have demonstrated the association between outdoor exposure to atmospheric particulate matter (PM) and adverse health effects, the actual chemical species responsible for PM toxicological properties remain a subject of investigation. We provide here reactive oxygen species (ROS) activity data for PM samples collected at a rural site in the Po Valley, Italy, during the fog season (i.e., November–March). We show that the intrinsic ROS activity of Po Valley PM, which is mainly composed of biomass burning and secondary aerosols, is comparable to that of traffic-related particles in urban areas. The airborne concentration of PM components responsible for the ROS activity decreases in fog conditions, when water-soluble species are scavenged within the droplets. Due to this partitioning effect of fog, the measured ROS activity of fog water was contributed mainly by water-soluble organic carbon (WSOC) and secondary inorganic ions rather than by transition metals. We found that the intrinsic ROS activity of fog droplets is even greater (> 2.5 times) than that of the PM on which droplets are formed, indicating that redox-active compounds are not only scavenged from the particulate phase, but are also produced within the droplets. Therefore, even if fog formation exerts a scavenging effect on PM mass and redox-active compounds, the aqueous-phase formation of reactive secondary organic compounds can eventually enhance ROS activity of PM when fog evaporates. These findings, based on a case study during a field campaign in November 2015, indicate that a significant portion of airborne toxicity in the Po Valley is largely produced by environmental conditions (fog formation and fog processing) and not simply by the emission and transport of pollutants.

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Section: Discussionmentioning

confidence: 58%

Enhanced toxicity of aerosol in fog conditions in the Po Valley, Italy

et al. 2017

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“…Transition metals, likely originating from fuel combustion, lube oil emissions, and, to a lesser extent, brake and tire wear [61,62], can be significant contributors to OP DTT . For example, Fe, Cu, and Mn can be highly reactive with DTT through Fenton reactions to produce H 2 O 2 , as shown in reactions (3)-(7) [49,63].…”

Section: The Oxidative Properties Of Various Chemical Compositionsmentioning

confidence: 99%

Use of Dithiothreitol Assay to Evaluate the Oxidative Potential of Atmospheric Aerosols

et al. 2019

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Oxidative potential (OP) has been proposed as a useful descriptor for the ability of particulate matter (PM) to generate reactive oxygen species (ROS) and consequently induce oxidative stress in biological systems, which has been recognized as one of the most important mechanisms responsible for PM toxicity. The dithiothreitol (DTT) assay is one of the most frequently used techniques to quantify OP because it is low-cost, easy-to-operate, and has high repeatability. With two thiol groups, DTT has been used as a surrogate of biological sulfurs that can be oxidized when exposed to ROS. Within the DTT measurement matrix, OP is defined as the DTT consumption rate. Often, the DTT consumption can be attributed to the presence of transition metals and quinones in PM as they can catalyze the oxidation of DTT through catalytic redox reactions. However, the DTT consumption by non-catalytic PM components has not been fully investigated. In addition, weak correlations between DTT consumption, ROS generation, and cellular responses have been observed in several studies, which also reveal the knowledge gaps between DTT-based OP measurements and their implication on health effects. In this review, we critically assessed the current challenges and limitations of DTT measurement, highlighted the understudied DTT consumption mechanisms, elaborated the necessity to understand both PM-bound and PM-induced ROS, and concluded with research needs to bridge the existing knowledge gaps.

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“…Recent literature show that some redox-active metals from brake wear (Cu, Fe, Mn, Cr) are associated with oxidative stress (Poprac et al, 2017), high oxidative potential (Shirmohammadi et al, 2017;Weber et al, 2018), and inflammation in lung tissue (Pardo et al, 2015). Also brake wear debris are associated with many health outcomes (Kukutschová et al, 2009).…”

Section: Discussionmentioning

confidence: 99%

“…There is now strong evidence that traffic-related PM are responsible for adverse health effects due to the health effect of both carbonaceous material from exhaust emissions and redox-active metals in traffic-generated dust including road, brake and tyre wear (Cassee et al, 2013 ;Amato et al, 2014 and references wherein). Recently, Shirmohammadi et al (2017) have shown the important role of non-tailpipe emissions to the oxidative potential of particulate matter species identified as tracers of vehicle abrasion. Therefore, a better knowledge on vehicular emissions is required to better understand their contribution to urban atmospheric PM concentration levels and related health effects.…”

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confidence: 99%

Identification and quantification of particulate tracers of exhaust and non-exhaust vehicle emissions

Charron¹,

Polo-Rehn²,

Besombes³

et al. 2018

Preprint

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<p><strong>Abstract.</strong> In order to identify and quantify key-species associated with non-exhaust emissions and exhaust vehicular emissions a large comprehensive dataset of particulate species has been obtained thanks to simultaneous near-road and urban background measurements coupled with detailed traffic counts and chassis dynamometer measurements of exhaust emissions of a few in-use vehicles well-represented in the French fleet. Elemental Carbon, brake-wear metals (Cu, Fe, Sb, Sn, Mn), n-alkanes (C19&#8211;C26), light molecular weight PAHs (Pyrene, Fluoranthene, Anthracene) and two hopanes (17&#945;21&#946;Norhopane and 17&#945;21&#946;hopane) are strongly associated with the road traffic. Traffic-fleet emission factors have been determined for all of them and are consistent with most recent published equivalent data. When possible, light-duty and heavy-duty duty traffic emission factors are also determined. Most of the first ones are in good agreement with emissions from chassis dynamometer measurements in absence of significant non-combustion emissions. This study has shown that ratios involving copper (mainly Cu/Fe and Cu/Sn) could be used to trace brake-wear emissions as they seem to be roughly constant in Europe and as longer as Cu-free brake are not largely spread. In France where the traffic was largely dominated by diesel vehicles in 2011 (70&#8201;%), the OC/EC ratio typical of traffic emissions was around 0.44. On the contrary, the use of quantitative data for source apportionment studies is not straightforward for the identified organic molecular markers; while, their presence seems to well-characterized fresh traffic emissions.</p>

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Oxidative potential of on-road fine particulate matter (PM 2.5 ) measured on major freeways of Los Angeles, CA, and a 10-year comparison with earlier roadside studies

Cited by 64 publications

References 75 publications

Enhanced toxicity of aerosol in fog conditions in the Po Valley, Italy

Enhanced toxicity of aerosol in fog conditions in the Po Valley, Italy

Use of Dithiothreitol Assay to Evaluate the Oxidative Potential of Atmospheric Aerosols

Identification and quantification of particulate tracers of exhaust and non-exhaust vehicle emissions

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