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Now showing items 1 - 16 of 73

  • A review of commuter exposure to ultrafine particles and its health effects

    Luke D. Knibbs   Tom Cole-Hunter   Lidia Morawska  

    Ultrafine particles (UFPs, <100 nm) are produced in large quantities by vehicular combustion and are implicated in causing several adverse human health effects. Recent work has suggested that a large proportion of daily UFP exposure may occur during commuting. However, the determinants, variability and transport mode-dependence of such exposure are not well-understood. The aim of this review was to address these knowledge gaps by distilling the results of 'in-transit' UFP exposure studies performed to-date, including studies of health effects.We identified 47 exposure studies performed across 6 transport modes: automobile, bicycle, bus, ferry, rail and walking. These encompassed approximately 3000 individual trips where UFP concentrations were measured. After weighting mean UFP concentrations by the number of trips in which they were collected, we found overall mean UFP concentrations of 3.4, 4.2, 4.5, 4.7, 4.9 and 5.7 x 10(4) particles cm(-3) for the bicycle, bus, automobile, rail, walking and ferry modes, respectively. The mean concentration inside automobiles travelling through tunnels was 3.0 x 10(5) particles cm(-3).While the mean concentrations were indicative of general trends, we found that the determinants of exposure (meteorology, traffic parameters, route, fuel type, exhaust treatment technologies, cabin ventilation, filtration, deposition, UFP penetration) exhibited marked variability and mode-dependence, such that it is not necessarily appropriate to rank modes in order of exposure without detailed consideration of these factors. Ten in-transit health effects studies have been conducted and their results indicate that UFP exposure during commuting can elicit acute effects in both healthy and health-compromised individuals. We suggest that future work should focus on further defining the contribution of in-transit UFP exposure to total UFP exposure, exploring its specific health effects and investigating exposures in the developing world. (C) 2011 Elsevier Ltd. All rights reserved.
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  • Exposure to ultrafine particles and PM2.5 in four Sydney transport modes

    Luke D. Knibbs   Richard J. de Dear  

    Concentrations of ultrafine (<0.1 mu m) particles (UFPs) and PM2.5 (<2.5 mu m) were measured whilst commuting along a similar route by train, bus, ferry and automobile in Sydney, Australia. One trip on each transport mode was undertaken during both morning and evening peak hours throughout a working week, for a total of 40 trips. Analyses comprised one-way ANOVA to compare overall (i.e. all trips combined) geometric mean concentrations of both particle fractions measured across transport modes, and assessment of both the correlation between wind speed and individual trip means of UFPs and PM2.5, and the correlation between the two particle fractions. Overall geometric mean concentrations of UFPs and PM2.5 ranged from 2.8 (train) to 8.4 (bus) x 10(4) particles cm(-3) and 22.6 (automobile) to 29.6 (bus) mu g m(-3), respectively, and a statistically significant difference (p < 0.001) between modes was found for both particle fractions. Individual trip geometric mean concentrations were between 9.7 x 10(3) (train) and 2.2 x 10(5) (bus) particles cm(-3) and 9.5 (train) to 78.7 (train) mu g m(-3). Estimated commuter exposures were variable, and the highest return trip mean PM2.5 exposure occurred in the ferry mode, whilst the highest UFP exposure occurred during bus trips. The correlation between fractions was generally poor, and in keeping with the duality of particle mass and number emissions in vehicle-dominated urban areas. Wind speed was negatively correlated with, and a generally poor determinant of, UFP and PM2.5 concentrations, suggesting a more significant role for other factors in determining commuter exposure. (C) 2010 Elsevier Ltd. All rights reserved.
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  • Exposure to ultrafine particles and PM2.5 in four Sydney transport modes

    Luke D. Knibbs   Richard J. de Dear  

    Concentrations of ultrafine (<0.1 μm) particles (UFPs) and PM2.5 (<2.5 μm) were measured whilst commuting along a similar route by train, bus, ferry and automobile in Sydney, Australia. One trip on each transport mode was undertaken during both morning and evening peak hours throughout a working week, for a total of 40 trips. Analyses comprised one-way ANOVA to compare overall (i.e. all trips combined) geometric mean concentrations of both particle fractions measured across transport modes, and assessment of both the correlation between wind speed and individual trip means of UFPs and PM2.5, and the correlation between the two particle fractions. Overall geometric mean concentrations of UFPs and PM2.5 ranged from 2.8 (train) to 8.4 (bus) × 104 particles cm−3 and 22.6 (automobile) to 29.6 (bus) μg m−3, respectively, and a statistically significant difference (p < 0.001) between modes was found for both particle fractions. Individual trip geometric mean concentrations were between 9.7 × 103 (train) and 2.2 × 105 (bus) particles cm−3 and 9.5 (train) to 78.7 (train) μg m−3. Estimated commuter exposures were variable, and the highest return trip mean PM2.5 exposure occurred in the ferry mode, whilst the highest UFP exposure occurred during bus trips. The correlation between fractions was generally poor, and in keeping with the duality of particle mass and number emissions in vehicle-dominated urban areas. Wind speed was negatively correlated with, and a generally poor determinant of, UFP and PM2.5 concentrations, suggesting a more significant role for other factors in determining commuter exposure.
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  • On-road ultrafine particle concentration in the M5 East road tunnel, Sydney, Australia

    Luke D. Knibbs   Richard J. de Dear   Lidia Morawska   Kerrie L. Mengersen  

    The human health effects following exposure to ultrafine (<100 nm) particles (UFPs) produced by fuel combustion, while not completely understood, are generally regarded as detrimental. Road tunnels have emerged as locations where maximum exposure to these particles may occur for the vehicle occupants using them. This study aimed to quantify and investigate the determinants of UFP concentrations in the 4 km twin-bore (eastbound and westbound) M5 East tunnel in Sydney, Australia. Sampling was undertaken using a condensation particle counter (CPC) mounted in a vehicle traversing both tunnel bores at various times of day from May through July, 2006. Supplementary measurements were conducted in February, 2008. Over three hundred transects of the tunnel were performed, and these were distributed evenly between the bores. Additional comparative measurements were conducted on a mixed route comprising major roads and shorter tunnels, all within Sydney. Individual trip average UFP concentrations in the M5 East tunnel bores ranged from 5.53 × 104 p cm−3 to 5.95 × 106 p cm−3. Data were sorted by hour of capture, and hourly median trip average (HMA) UFP concentrations ranged from 7.81 × 104 p cm−3 to 1.73 × 106 p cm−3. Hourly median UFP concentrations measured on the mixed route were between 3.71 × 104 p cm−3 and 1.55 × 105 p cm−3. Hourly heavy diesel vehicle (HDV) traffic volume was a very good determinant of UFP concentration in the eastbound tunnel bore (R2 = 0.87), but much less so in the westbound bore (R2 = 0.26). In both bores, the volume of passenger vehicles (i.e. unleaded gasoline-powered vehicles) was a significantly poorer determinant of particle concentration. When compared with similar studies reported previously, the measurements described here were among the highest recorded concentrations, which further highlights the contribution road tunnels may make to the overall UFP exposure of vehicle occupants.
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  • On-road ultrafine particle concentration in the M5 East road tunnel, Sydney, Australia

    Luke D. Knibbs   Richard J. de Dear   Lidia Morawska   Kerrie L. Mengersen  

    The human health effects following exposure to ultrafine (<100 nm) particles (UFPs) produced by fuel combustion, while not completely understood, are generally regarded as detrimental. Road tunnels have emerged as locations where maximum exposure to these particles may occur for the vehicle occupants using them. This study aimed to quantify and investigate the determinants of UFP concentrations in the 4 km twin-bore (eastbound and westbound) M5 East tunnel in Sydney, Australia. Sampling was undertaken using a condensation particle counter (CPC) mounted in a vehicle traversing both tunnel bores at various times of day from May through July, 2006. Supplementary measurements were conducted in February, 2008. Over three hundred transects of the tunnel were performed, and these were distributed evenly between the bores. Additional comparative measurements were conducted on a mixed route comprising major roads and shorter tunnels, all within Sydney. Individual trip average UFP concentrations in the M5 East tunnel bores ranged from 5.53 x 10(4) p cm(-3) to 5.95 x 10(6) p cm(-3). Data were sorted by hour of capture, and hourly median trip average (HMA) UFP concentrations ranged from 7.81 x 10(4) p cm(-3) to 1.73 x 10(6) p cm(-3). Hourly median UFP concentrations measured on the mixed route were between 3.71 x 10(4) p cm(-3) and 1.55 x 10(5) p cm(-3). Hourly heavy diesel vehicle (HDV) traffic volume was a very good determinant of UFP concentration in the eastbound tunnel bore (R-2 = 0.87), but much less so in the westbound bore (R-2 = 0.26). In both bores, the volume of passenger vehicles (i.e. unleaded gasoline-powered vehicles) was a significantly poorer determinant of particle concentration. When compared with similar studies reported previously, the measurements described here were among the highest recorded concentrations, which further highlights the contribution road tunnels may make to the overall UFP exposure of vehicle occupants. (C) 2009 Elsevier Ltd. All rights reserved.
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  • A simple and inexpensive dilution system for the TSI 3007 condensation particle counter

    Luke D. Knibbs   Richard J. de Dear   Lidia Morawska    Peter M. Coote  

    The aim of this study was to develop a dilution system which would permit the TSI 3007 condensation particle counter (CPC) to operate within its maximum detectable concentration threshold, even when sampling extremely high submicron particle concentrations. The intention of this was to provide a better alternative to coincidence correction factors, which have several limitations; the most significant of which being that they are only applicable to a comparatively low concentration and also that the components of the unit are exposed to concentrations beyond their operating specifications. To achieve the aim, a bifurcation-based system was developed and tested repeatedly at concentrations of unleaded petrol combustion particles up to 8.5×106 p cm−3. The benchmark particle concentration was measured by a TSI 3022A CPC. The results of the tests showed that the nominal dilution ratio based on flow partitioning was applicable up to 3.5×105 p cm−3, after which particle losses to a capillary tube primarily caused a large increase in apparent dilution. These losses were consistent throughout all tests and allowed the unit to remain below the maximum detection threshold, even under the extreme challenge concentrations encountered. This work represents a useful extension of the operating range of the TSI 3007, without significantly compromising either the quality of data collected or the internal components of the unit.
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  • A simple and inexpensive dilution system for the TSI 3007 condensation particle counter

    Luke D. Knibbs   Richard J. de Dear   Lidia Morawska   Peter M. Coote  

    The aim of this study was to develop a dilution system which would permit the TSI 3007 condensation particle counter (CPC) to operate within its maximum detectable concentration threshold, even when sampling extremely high submicron particle concentrations. The intention of this was to provide a better alternative to coincidence correction factors, which have several limitations; the most significant of which being that they are only applicable to a comparatively low concentration and also that the components of the unit are exposed to concentrations beyond their operating specifications. To achieve the aim, a bifurcation-based system was developed and tested repeatedly at concentrations of unleaded petrol combustion particles up to 8.5×106 p cm−3. The benchmark particle concentration was measured by a TSI 3022A CPC. The results of the tests showed that the nominal dilution ratio based on flow partitioning was applicable up to 3.5×105 p cm−3, after which particle losses to a capillary tube primarily caused a large increase in apparent dilution. These losses were consistent throughout all tests and allowed the unit to remain below the maximum detection threshold, even under the extreme challenge concentrations encountered. This work represents a useful extension of the operating range of the TSI 3007, without significantly compromising either the quality of data collected or the internal components of the unit.
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  • Room ventilation and the risk of airborne infection transmission in 3?health care settings within a large teaching hospital

    Luke D. Knibbs   Lidia Morawska   Scott C. Bell   Piotr Grzybowski  

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  • The Author File: Luke D. Lavis

    Marx   Vivien  

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  • Toward a Critical Sociology of Reading Pedagogyby Carolyn D. Baker; Allan Luke

    Review by: Janet Swaffar  

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  • Mark and Luke in Poststructuralist Perspectives: Jesus Begins to Writeby Stephen D. Moore

    Review by: Jeffrey L. Staley  

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  • Mark and Luke in Poststructuralist Perspectives: Jesus Begins to Writeby Stephen D. Moore

    Review by: Alan G. Lindsay  

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  • 3Ist October: Trinity 2I SELF-WORTH By the Revd John D. Searle, BA, BD Carterton, Oxfordshire Luke I9:I-I0

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  • Four Views on the Apostle Paul - By Thomas R. Schreiner, Luke Timothy Johnson, Douglas A. Campbell and Mark D. Nanos

    Matthew P. O'Reilly  

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  • Carolyn D. Baker and Allan Luke (eds.)\r Towards a Critical Sociology of Reading Pedagogy

    Varro   Gabrielle  

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  • John D. Zizioulas, The Eucharistic Communion and the World, ed. Luke BenTallon. London: T. & T. Clark, 2011, xv + 186pp. £19.99 / $34.95

    Nelson   R. David  

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