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- Dahl, Andreas, et al.
(författare)
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Traffic-generated emissions of ultrafine particles from pavement-tire interface
- 2006
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Ingår i: Atmospheric Environment. - : Elsevier. - 1352-2310 .- 1873-2844. ; 40:7, s. 1314-1323
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Tidskriftsartikel (refereegranskat)abstract
- In a road simulator study, a significant source of sub-micrometer fine particles produced by the road-tire interface was observed. Since the particle size distribution and source strength is dependent on the type of tire used, it is likely that these particles largely originate from the tires, and not the road pavement. The particles consisted most likely of mineral oils from the softening filler and fragments of the carbon-reinforcing filler material (soot agglomerates). This identification was based on transmission electron microscopy studies of collected ultrafine wear particles and on-line thermal treatment using a thermodesorber. The mean particle number diameters were between 15-50 nm, similar to those found in light duty vehicle (LDV) tail-pipe exhaust. A simple box model approach was used to estimate emission factors in the size interval 15-700 nm. The emission factors increased with increasing vehicle speed, and varied between 3.7 x 10(11) and 3.2 x 10(12) particles vehicle(-1) km(-1) at speeds of 50 and 70 km h(-1). This corresponds to between 0.1-1% of tail-pipe emissions in real-world emission studies at similar speeds from a fleet of LDV with 95% gasoline and 5% diesel-fueled cars. The emission factors for particles originating from the road-tire interface were, however, similar in magnitude to particle number emission factors from liquefied petroleum gas-powered vehicles derived in test bench studies in Australia 2005. Thus the road-tire interface may be a significant contributor to particle emissions from ultraclean vehicles. (c) 2005 Elsevier Ltd. All rights reserved.
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- Gustafsson, Mats, et al.
(författare)
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Inandningsbara partiklar från dubbdäcksslitage av vägbana : egenskaper och inflammatoriska effekter i mänskliga luftvägsceller. utdrag ur WearTox-projektet (VTI rapport 520)
- 2005
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- The aims of this project have been to describe PM10 from studded tyre wear and to study their inflammatory effects in human airway cells. The VTI circular road simulator has been used to generate "clean" wear particles from two different pavements; asphalt concrete (ABT) and stone mastic asphalt (ABS), with granite respectively quartzite as the main stone materials. The advantage of using the road simulator is that the contribution from other sources can be minimised. During the project time, the project was expanded also to study particle generation by non-studded winter tyres (friction tyres) and two kinds of winter sanding agents, namely washed crushed stone and unwashed natural sand in combination with both studded and friction tyres. Most of these parts of the project are presented in VTI report 520. The results show that pavement wear by studded tyres generates about 40-50 times as much PM10 as that by friction tyres, but also that the ABT pavement generates several times more PM10 than the ABS pavement. The size distribution within PM10 has a maximum around 3-4 ?m and more than 95 % of the mass is larger than 1 ?m. PM10 is totally dominated by fresh stone material. A fraction of very small particles, with a number concentration peak at around 30-40 nm, was also discovered. Their origin is unknown, but since the number distribution shifted depending on which tyre type was used, a possible origin is the tyres. In the cell studies the inflammation potential of the wear particles was compared with PM10 from Hornsgatan in Stockholm and PM10 from a Stockholm subway station. Later on in the project, diesel particles were made available for comparison. The cell study results show that PM10 from the ABT pavement is at least as inflammatory as diesel particles and more inflammatory than PM10 from the subway. The PM10 from Hornsgatan generally had the highest potential, but PM10 from the ABT pavement was often in parity. This despite the fact that the Hornsgatan PM10 were the only particle sample where endotoxin could be detected. Endotoxin causes an additive effect in studies of inflammation potential. PM10 from the ABS pavement generally had a lower potential than PM10 from the ABT pavement.
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- Gustafsson, Mats, et al.
(författare)
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Inandningsbara partiklar från interaktion mellan däck, vägbana och friktionsmaterial : slutrapport av WearTox-projektet
- 2005
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Rapport (populärvet., debatt m.m.)abstract
- The aims of this project have been to describe PM10 from studded tyre wear and to study their inflammatory effects in human airway cells. The VTI circular road simulator has been used to generate "clean" wear particles from two different pavements; asphalt concrete (ABT) and stone mastic asphalt (ABS), with granite respectively quartzite as the main stone materials. The advantage of using the road simulator is that the contribution from other sources can be minimised. During the project time, the project was expanded also to study particle generation by non-studded winter tyres (friction tyres) and two kinds of winter sanding agents, namely washed crushed stone and unwashed natural sand in combination with both studded and friction tyres. The results show that pavement wear by studded tyres generates about 40-50 times as much PM10 as that by friction tyres, but also that the ABT pavement generates several times more PM10 than the ABS pavement. The size distribution within PM10 has a maximum around 3-4 ?m and more than 95 % of the mass is larger than 1 ?m. PM10 is totally dominated by fresh stone material. A fraction of very small particles, with a number concentration peak at around 30-40 nm, was also discovered. Their origin is unknown, but since the number distribution shifted depending on which tyre type was used, a possible origin is the tyres. In the experiments using sanding material, the unwashed natural sand caused the highest PM10 concentrations. Friction tyres on natural sand caused higher concentrations than studded tyres on washed crushed stone. Studded tyres generated more PM10 than friction tyres but the difference was not as large as when no sanding material was used. In the cell studies the inflammation potential of the wear particles was compared with PM10 from Hornsgatan in Stockholm and PM10 from a Stockholm subway station. Later on in the project, diesel particles were made available for comparison. The cell study results show that PM10 from the ABT pavement is at least as inflammatory as diesel particles and more inflammatory than PM10 from the subway. The PM10 from Hornsgatan generally had the highest potential, but PM10 from the ABT pavement was often in parity. This despite the fact that the Hornsgatan PM10 were the only particle sample where endotoxin could be detected. Endotoxin causes an additive effect in studies of inflammation potential. PM10 from the ABS pavement generally had a lower potential than PM10 from the ABT pavement.
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- Gustafsson, Mats, et al.
(författare)
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Inandningsbara partiklar i järnvägsmiljöer
- 2006
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Airborne particles from railroad traffic have been identified as an air pollution problem mainly in tunnel environments. As a result of the introduction of the environmental quality standard for inhalable particles in Sweden 2005, the interest in railroad particle pollution has increased. The present report focuses on the variation of PM10 (inhalable particles) in some railroad environments under and above ground, the way these relate to traffic and on the particles' size distributions and elemental composition. The results show that particle concentrations in above ground railroad environments do not exceed the environmental quality standard during the campaigns. Diurnal mean values of PM10 range between 19 to 25 microg/m3. On the contrary, the diurnal mean concentrations on the platforms of the underground stations Arlanda Central and Arlanda South are far above the limit value (237 and 88 microg/m3 respectively) and clear diurnal and weekly patterns in PM10 concentration, co-fluctuating with traffic, can be identified. The particle mass size distribution has an obvious peak around 5-7 ?m at Arlanda C, and slightly smaller, 2-3 microm, at Arlanda S. The concentrations of both PM10 and ultrafine particles (< 0,1 microm) vary a lot depending on different trains. Especially the ultrafine particles seem to be emitted from certain trains, but it has not been possible to identify the source of these particles. The elemental composition of the particles in the tunnel environments was dominated by iron (84 % and 74 % respectively in Arlanda C and Arlanda S), but also other metals, like Cu, Zn, Cr, Ni and Sb (only at Arlanda C) have relatively high concentrations. The tunnel measurements also give some interesting results regarding possible measures against high particle concentrations. Washing of the tunnel walls and floor was carried out on two consecutive nights, but it had no noticeable results on particle concentrations. This implies that a dominant proportion of the particles is directly emitted rather than resuspended. On certain nights, the concentrations of all particle size fractions sank to very low levels, lasting till the morning traffic began. This implies effective self ventilation during these hours. Measurements in several different environments on Stockholm central station show that PM10 vary several tens of microg/m3. Activity, related to both traffic and people, increases particle concentration. The highest concentrations were measured inside the waiting hall. Nevertheless, the concentrations on the platforms were generally at least as high as in the busy street environment outside the station. During a railroad travel, the PM10 and PM2,5 concentrations were generally low, but increase at stops and, most prominently, on entering the Arlanda airport railroad tunnels. The PM2,5 proportion is considered high, contributing to approximately 50-80 % of PM10. The sources of railroad emitted PM10 are likely to be rails, wheels and brakes, but a source apportionment has not been accomplished in this project.
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