Sources and properties of non-exhaust particulate matter from road traffic: a review.
TL;DR: It is concluded that with the exception of brake dust particles which may be identified from their copper (Cu) and antimony (Sb) content, unequivocal identification of particles from other sources is likely to prove extremely difficult, either because of the lack of suitable tracer elements or compounds, or of the interactions between sources prior to the emission process.
About: This article is published in Science of The Total Environment.The article was published on 2008-08-01. It has received 1290 citations till now. The article focuses on the topics: Road surface.
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TL;DR: In this paper, the authors reviewed the nature of the particle emissions from road vehicles including both exhaust and non-exhaust (abrasion and re-suspension sources) and briefly reviewed the various methods available for quantification of the road traffic contribution.
891 citations
Cites background from "Sources and properties of non-exhau..."
...Most of the research as well as policy action in the last few decades has largely focused on exhaust emissions, and stringent regulations and technological upgrades have resulted in a decline of the percentage contribution of vehicle tailpipe emissions to total ambient PM concentrations (Allen et al., 2006; Thorpe and Harrison, 2008; Mathissen et al., 2011)....
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...5-10) or by volatilization (Rogge et al., 1993; Kupiainen et al., 142 2005; Allen et al., 2006; Thorpe and Harrison, 2008; Aatmeeyata and Sharma, 2010)....
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...Road traffic frequently makes a very significant contribution (5e 80% depending on site and location) to airborne concentrations of PM, whether expressed in terms of particle mass or number concentration (Thorpe and Harrison, 2008; Belis et al., 2013)....
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...A number of in-depth review articles have been published in the last few years on various issues related to road traffic emissions on topics such as properties and characteristics of non-exhaust emissions (Thorpe and Harrison, 2008), toxicological impacts of tyre wear emissions (Wik and Dave, 2009), chemical composition of brake pads (Chan and Stachowiak, 2004), development of emission factors (Franco et al....
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...CONCLUSIONS 919 Road traffic frequently makes a very significant contribution (5-80% depending on site and location) 920 to airborne concentrations of PM, whether expressed in terms of particle mass or number 921 concentration (Thorpe and Harrison, 2008; Belis et al., 2013)....
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01 Jan 2013
TL;DR: In this paper, the authors present answers to 24 questions relevant to reviewing European policies on air pollution and to addressing health aspects of these policies, which were developed by a large group of scientists engaged in the WHO project REVIHAAP.
Abstract: This document presents answers to 24 questions relevant to reviewing European policies on air pollution and to addressing health aspects of these policies. The answers were developed by a large group of scientists engaged in the WHO project “Review of evidence on health aspects of air pollution – REVIHAAP”. The experts reviewed and discussed the newly accumulated scientific evidence on the adverse effects on health of air pollution, formulating science-based answers to the 24 questions. Extensive rationales for the answers, including the list of key references, are provided. The review concludes that a considerable amount of new scientific information on the adverse effects on health of particulate matter, ozone and nitrogen dioxide, observed at levels commonly present in Europe, has been published in recent years. This new evidence supports the scientific conclusions of the WHO air quality guidelines, last updated in 2005, and indicates that the effects in some cases occur at air pollution concentrations lower than those serving to establish these guidelines. It also provides scientific arguments for taking decisive actions to improve air quality and reduce the burden of disease associated with air pollution in Europe. This publication arises from the project REVIHAAP and has been co-funded by the European Union.
744 citations
TL;DR: It is concluded here that tyre wear and tear is a stealthy source of microplastics in the authors' environment, which can only be addressed effectively if awareness increases, knowledge gaps on quantities and effects are being closed, and creative technical solutions are being sought.
Abstract: Wear and tear from tyres significantly contributes to the flow of (micro-)plastics into the environment. This paper compiles the fragmented knowledge on tyre wear and tear characteristics, amounts of particles emitted, pathways in the environment, and the possible effects on humans. The estimated per capita emission ranges from 0.23 to 4.7 kg/year, with a global average of 0.81 kg/year. The emissions from car tyres (100%) are substantially higher than those of other sources of microplastics, e.g., airplane tyres (2%), artificial turf (12–50%), brake wear (8%) and road markings (5%). Emissions and pathways depend on local factors like road type or sewage systems. The relative contribution of tyre wear and tear to the total global amount of plastics ending up in our oceans is estimated to be 5–10%. In air, 3–7% of the particulate matter (PM2.5) is estimated to consist of tyre wear and tear, indicating that it may contribute to the global health burden of air pollution which has been projected by the World Health Organization (WHO) at 3 million deaths in 2012. The wear and tear also enters our food chain, but further research is needed to assess human health risks. It is concluded here that tyre wear and tear is a stealthy source of microplastics in our environment, which can only be addressed effectively if awareness increases, knowledge gaps on quantities and effects are being closed, and creative technical solutions are being sought. This requires a global effort from all stakeholders; consumers, regulators, industry and researchers alike.
628 citations
Cites background from "Sources and properties of non-exhau..."
...Due to their small size, electrostatic forces may result in adsorption of nanoparticles to the road surface or vehicle carcass [71]....
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TL;DR: This article reviews the current approaches to source apportionment of ambient particles and the latest evidence for their health effects, and describes the current metrics, policies and legislation for the protection of public health from ambient particles.
Abstract: The diversity of ambient particle size and chemical composition considerably complicates pinpointing the specific causal associations between exposure to particles and adverse human health effects, the contribution of different sources to ambient particles at different locations, and the consequent formulation of policy action to most cost-effectively reduce harm caused by airborne particles. Nevertheless, the coupling of increasingly sophisticated measurements and models of particle composition and epidemiology continue to demonstrate associations between particle components and sources (and at lower concentrations) and a wide range of adverse health outcomes. This article reviews the current approaches to source apportionment of ambient particles and the latest evidence for their health effects, and describes the current metrics, policies and legislation for the protection of public health from ambient particles. A particular focus is placed on particles in the ultrafine fraction. The review concludes with an extended evaluation of emerging challenges and future requirements in methods, metrics and policy for understanding and abating adverse health outcomes from ambient particles.
580 citations
TL;DR: The aim of the present literature review study is to present the state-of-the-art of the different aspects regarding PM resulting from brake wear and provide all the necessary information in terms of importance, physicochemical characteristics, emission factors and possible health effects.
Abstract: Traffic-related sources have been recognized as a significant contributor of particulate matter particularly within major cities. Exhaust and non-exhaust traffic-related sources are estimated to contribute almost equally to traffic-related PM10 emissions. Non-exhaust particles can be generated either from non-exhaust sources such as brake, tyre, clutch and road surface wear or already exist in the form of deposited material at the roadside and become resuspended due to traffic-induced turbulence. Among non-exhaust sources, brake wear can be a significant particulate matter (PM) contributor, particularly within areas with high traffic density and braking frequency. Studies mention that in urban environments, brake wear can contribute up to 55 % by mass to total non-exhaust traffic-related PM10 emissions and up to 21 % by mass to total traffic-related PM10 emissions, while in freeways, this contribution is lower due to lower braking frequency. As exhaust emissions control become stricter, relative contributions of non-exhaust sources—and therefore brake wear—to traffic-related emissions will become more significant and will raise discussions on possible regulatory needs. The aim of the present literature review study is to present the state-of-the-art of the different aspects regarding PM resulting from brake wear and provide all the necessary information in terms of importance, physicochemical characteristics, emission factors and possible health effects.
554 citations
Cites background or methods or result from "Sources and properties of non-exhau..."
...Brake linings generally comprise five main components: binders, fibres, fillers, frictional additives or lubricants and abrasives (Boulter 2006; Chan and Stachowiak 2004; Kukutschová et al. 2011; Thorpe and Harrison 2008; Wahlström 2009; Wahlström 2011)....
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...%) has been reported in older studies (Thorpe and Harrison 2008), with however latest studies showing a remarkable decrease (0....
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...…emission are tyre, brake, clutch and road surface wear, with other potential sources being engine wear, abrasion of wheel bearings and corrosion of other vehicle components, street furniture and crash barriers (Barlow et al. 2007; Boulter 2006; Pant and Harrison 2013; Thorpe and Harrison 2008)....
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...Other metals such as Ba, Mg, Mn, Ni, Sn, Cd, Cr, Ti, K and Sb have also been found in concentrations lower than 0.1 wt.% (Boulter 2006; Kukutschová et al. 2011; Thorpe and Harrison 2008)....
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...The most important abrasion processes which result in direct particulate matter (PM) emission are tyre, brake, clutch and road surface wear, with other potential sources being engine wear, abrasion of wheel bearings and corrosion of other vehicle components, street furniture and crash barriers (Barlow et al. 2007; Boulter 2006; Pant and Harrison 2013; Thorpe and Harrison 2008)....
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References
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TL;DR: It is concluded that tire dust consists not only of the debris from tire wear but also of assimilated heavy metal particles emitted from road traffic materials such as brake lining and road paint.
797 citations
TL;DR: In this article, metal emissions from road traffic were studied in two heavily trafficked tunnels in Gothenburg, Sweden, and five runs were made in each tunnel, generally extending over several hours, during which air concentrations of metals in tunnel inlet and outlet, traffic flow and composition and air ventilation were determined.
788 citations
TL;DR: In this paper, the organic constituents present in fine particulate (d_p ≤ 2.0 µm) road dust, brake lining particles, and tire tread debris (not size segregated) were analyzed using gas chromatography/mass spectrometry.
Abstract: Particulate matter emitted to the atmosphere due to motor
vehicles arises from several sources in addition to tailpipe
exhaust. In this study, the organic constituents present
in fine particulate (d_p ≤ 2.0 µm) road dust, brake lining
wear particles, and tire tread debris (not size segregated)
are analyzed using gas chromatography/mass spectrometry.
The objective is to characterize such traffic-related
sources on an organic compound basis and to search for
molecular markers that will assist the identification of
traffic-associated dusts in the urban atmosphere. More
than 100 organic compounds are quantified in these
samples, including n-alkanes, n-alkanoic acids, n-alkenoic
acids, n-alkanals, n-alkanols, benzoic acids, benzaldehydes,
polyalkylene glycol ethers, PAH, oxy-PAH, steranes,
hopanes, natural resins and other compound classes.
Paved road dust acts as a repository for vehicle-related
particles, which can then be resuspended by the passing
traffic. To evaluate the contributions from major urban
sources to the road dust complex, source profiles representing different types of vehicle exhaust, brake dust, tire debris, and vegetative detritus are compared, and their fractional contributions are estimated using several groups of organic tracer compounds. Likewise, the close relationship between airborne fine particulate organic constituents and road dust organic matter is discussed.
705 citations
TL;DR: Emissions of metals and other particle-phase species from on-road motor vehicles were measured in two tunnels in Milwaukee, WI during the summer of 2000 and winter of 2001 and correlations between these elements in PM2.5 indicate that direct brake wear emissions are also important.
Abstract: Emissions of metals and other particle-phase species from on-road motor vehicles were measured in two tunnels in Milwaukee, WI during the summer of 2000 and winter of 2001. Emission factors were calculated from measurements of fine (PM2.5) and coarse (PM10) particulate matter at tunnel entrances and exits, and effects of fleet composition and season were investigated. Cascade impactors (MOUDI) were used to obtain size-resolved metal emission rates. Metals were quantified with inductively-coupled plasma mass spectrometry (ICP-MS) and X-ray fluorescence (XRF). PM10 emission rates ranged from 38.7 to 201 mg km(-1) and were composed mainly of organic carbon (OC, 30%), inorganic ions (sulfate, chloride, nitrate, ammonium, 20%), metals (19%), and elemental carbon (EC, 9.3%). PM10 metal emissions were dominated by crustal elements Si, Fe, Ca, Na, Mg, Al, and K, and elements associated with tailpipe emissions and brake and tire wear, including Cu, Zn, Sb, Ba, Pb, and S. Metals emitted in PM2.5 were lower (11.6% of mass). Resuspension of roadway dust was dependent on weather and road surface conditions, and increased emissions were related to higher traffic volumes and fractions of heavy trucks. Emission of noble metals from catalytic converters appeared to be impacted by the presence of older vehicles. Elements related to brake wear were impacted by enriched road dust resuspension, but correlations between these elements in PM2.5 indicate that direct brake wear emissions are also important. A submicrometer particle mode was observed in the emissions of Pb, Ca, Fe, and Cu.
700 citations
TL;DR: In this paper, a dilution source sampling system was used to collect primary organic aerosol emissions from important sources, including a boiler burning No 2 fuel, a home fireplace, a fleet of catalyst-equipped and non-catalyst automobiles, heavy-duty diesel trucks, natural gas home appliances, and meat cooking operations.
Abstract: A dilution source sampling system was used to collect
primary fine aerosol emissions from important sources of
urban organic aerosol, including a boiler burning No 2 fuel
oil, a home fireplace, a fleet of catalyst-equipped and
noncatalyst automobiles, heavy-duty diesel trucks, natural
gas home appliances, and meat cooking operations Alternative
dilution sampling techniques were used to collect
emissions from cigarette smoking and a roofing tar pot,
and grab sample techniques were employed to characterize
paved road dust, brake lining wear, tire wear, and vegetative
detritus Organic aerosol constituted the majority
of the fine aerosol mass emitted from many of the sources
tested Fine primary organic aerosol emissions within the
heavily urbanized western portion of the Los Angeles Basin
were determined to total 298 metric tons/day Over 40%
of these organic aerosol emissions are from anthropogenic
pollution sources that are expected to emit contemporary
(nonfossil) aerosol carbon, in good agreement with the
available ambient monitoring data
670 citations