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- Dahl, Andreas, et al.
(author)
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Traffic-generated emissions of ultrafine particles from pavement-tire interface
- 2006
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In: Atmospheric Environment. - : Elsevier. - 1352-2310 .- 1873-2844. ; 40:7, s. 1314-1323
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Journal article (peer-reviewed)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.
(author)
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Properties and toxicological effects of particles from the interaction between tyres, road pavement and winter traction material
- 2008
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In: Science of the Total Environment. - : Institutionen för klinisk och experimentell medicin. - 0048-9697 .- 1879-1026. ; 393:2-3, s. 226-240
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Journal article (peer-reviewed)abstract
- In regions where studded tyres and traction material are used during winter, e.g. the Nordic countries, northern part of USA, Canada, and Japan, mechanically generated particles from traffic is the main reason for high particle concentrations in busy street- and road environments. In many Nordic municipalities the European environmental quality standard for inhalable particles (PM10) is exceeded due to these particles. In this study, particles from the wear of studded and studless friction tyres on two pavements and traction sanding were generated using a road simulator. The particles were characterized using particle sizers, PIXE and electron microscopy. Cell studies were conducted on particles sampled from the tests with studded tyres and compared with street environment, diesel exhaust and subway PM10, respectively. The results show that in the road simulator, where resuspension is minimised, studded tyres produce tens of times more particles than friction tyres. Chemical analysis of the sampled particles shows that the generated wear particles consists almost entirely of minerals from the pavement stone material, but also that S is enriched for the sub-micron particles and that Zn is enriched for friction tyres for all particles sizes. The chemical data can be used for source identification and apportionment in urban aerosol studies. A mode of ultra-fine particles was also present and is hypothesised to originate in the tyres. Further, traction material properties affect PM10 emission. The inflammatory potential of the particles from wear of pavements seems to depend on type of pavement and can be at least as potent as diesel exhaust particles. The results implies that there is a need and a good potential to reduce particle emission from pavement wear and winter time road and street operation by adjusting both studded tyre use as well as pavement and traction material properties.
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- Akselsson, Roland, et al.
(author)
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Aerosoler
- 1994
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Book (other academic/artistic)
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- Alsved, Malin, et al.
(author)
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Sources of Airborne Norovirus in Hospital Outbreaks
- 2020
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In: Clinical Infectious Diseases. - : Oxford University Press (OUP). - 1537-6591 .- 1058-4838. ; 70:10, s. 2023-2028
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Journal article (peer-reviewed)abstract
- BACKGROUND: Noroviruses are the major cause of viral gastroenteritis. Disease transmission is difficult to prevent and outbreaks in healthcare facilities commonly occur. Contact with infected persons and contaminated environments are believed to be the main routes of transmission. However, noroviruses have recently been found in aerosols and airborne transmission has been suggested. The aim of our study was to investigate associations between symptoms of gastroenteritis and presence of airborne norovirus, and to investigate the size of norovirus carrying particles.METHODS: Air sampling was repeatedly performed close to 26 patients with norovirus infections. Samples were analysed for norovirus RNA by RT-qPCR. The times since the patients' last episodes of vomiting and diarrhoea were recorded. Size separating aerosol particle collection was also performed in ward corridors.RESULTS: Norovirus RNA was found in 21 (24%) of 86 air samples from 10 different patients. Only air samples during outbreaks, or before a succeeding outbreak, tested positive for norovirus RNA. Airborne norovirus RNA was also strongly associated with a shorter time period since the last vomiting episode (odds ratio 8.1, p=0.04 within 3 hours since the last vomiting episode). The concentration of airborne norovirus ranged from 5-215 copies/m3, and detectable amounts of norovirus RNA were found in particles <0.95 µm and >4.51 µm.CONCLUSIONS: The results suggest that recent vomiting is the major source of airborne norovirus and imply a connection between airborne norovirus and outbreaks. The presence of norovirus RNA in submicrometre particles indicates that airborne transmission can be an important transmission route.
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