| 11. |
- Degrendele, Céline, et al.
(author)
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Size specific distribution of the atmospheric particulate PCDD/Fs, dl-PCBs and PAHs on a seasonal scale : Implications for cancer risks from inhalation
- 2014
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In: Atmospheric Environment. - : Elsevier. - 1352-2310 .- 1873-2844. ; 98, s. 410-416
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Journal article (peer-reviewed)abstract
- This study presents the seasonal size distribution of particulate polycyclic aromatic hydrocarbons (PAHs), polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) and dioxin-like polychlorinated biphenyls (dl-PCBs) in the atmosphere. Particles were sampled from October 2009 to October 2010 on a seasonal basis using a cascade impactor collecting six size fractions at a rural and urban site in the Brno area, Czech Republic. Higher concentrations of PAHs, PCDD/Fs and dl-PCBs were observed in cold seasons at both sites, attributed to the seasonality of the gas-particle partitioning, the increase of emissions and the lower boundary mixing layer in winter. All of the compounds showed a strong accumulation in the fine fraction, with, on average, 71% of Sigma PAHs, 73% of Sigma PCDD/Fs and 60% of Sigma dl-PCBs associated with particles <0.95 mu m. The human risk assessment via inhalation was addressed and followed the same pattern as for concentrations, with 41 and 7 times higher risk in winter compared to summer at the rural and urban sites, respectively. More than 70% of cancer risks of PAHs, PCDD/Fs and dl-PCBs was associated with particles <0.95 mu m. Moreover, an overestimation of the cancer risk via inhalation of up to 50% occurred when the size distribution of related compounds was not considered.
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| 12. |
- Denby, Bruce Rolstad, et al.
(author)
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A coupled road dust and surface moisture model to predict non-exhaust road traffic induced particle emissions (NORTRIP). Part 1 : Road dust loading and suspension modelling
- 2013
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In: Atmospheric Environment. - : Elsevier BV. - 1352-2310 .- 1873-2844. ; 77, s. 283-300
-
Journal article (peer-reviewed)abstract
- Non-exhaust traffic induced emissions are a major source of particle mass in most European countries. This is particularly important in Nordic and Alpine countries where winter time road traction maintenance occurs, e.g. salting and sanding, and where studded tyres are used. In this paper, Part 1, the road dust sub-model of a coupled road dust and surface moisture model (NORTRIP) is described. The model provides a generalised process based formulation of the non-exhaust emissions, with emphasis on the contribution of road wear, suspension, surface dust loading and the effect of road surface moisture (retention of wear particles and suspended emissions). The model is intended for use as a tool for air quality managers to help study the impact of mitigation measures and policies. We present a description of the road dust sub-model and apply the model to two sites in Stockholm and Copenhagen where seven years of data with surface moisture measurements are available. For the site in Stockholm, where studded tyres are in use, the model predicts the PM10 concentrations very well with correlations (R-2) in the range of R-2 = 0.76-0.91 for daily mean PM10. The model also reproduces well the impact of a reduction in studded tyres at this site. For the site in Copenhagen the correlation is lower, in the range 0.44-0.51. The addition of salt is described in the model and at both sites this leads to improved correlations due to additional salt emissions. For future use of the model a number of model parameters, e.g. wear factors and suspension rates, still need to be refined. The effect of sanding on PM10 emissions is also presented but more information will be required before this can be confidently applied for management applications. (C) 2013 Elsevier Ltd. All rights reserved.
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| 13. |
- Denby, Bruce Rolstad, et al.
(author)
-
A coupled road dust and surface moisture model to predict non-exhaust road traffic induced particle emissions (NORTRIP). Part 2 : Surface moisture and salt impact modelling
- 2013
-
In: Atmospheric Environment. - : Elsevier. - 1352-2310 .- 1873-2844. ; 81, s. 485-503
-
Journal article (peer-reviewed)abstract
- Non-exhaust traffic induced emissions are a major source of airborne particulate matter in most European countries. This is particularly important in Nordic and Alpine countries where winter time road traction maintenance occurs, e.g. salting and sanding, and where studded tyres are used. Though the total mass generated by wear sources is a key factor in non-exhaust emissions, these emissions are also strongly controlled by surface moisture conditions. In this paper, Part 2, the road surface moisture submodel of a coupled road dust and surface moisture model (NORTRIP) is described.We present a description of the road surface moisture part of the model and apply the coupled model to seven sites in Stockholm, Oslo, Helsinki and Copenhagen over 18 separate periods, ranging from 3.5 to 24 months. At two sites surface moisture measurements are available and the moisture sub-model is compared directly to these observations. The model predicts the frequency of wet roads well at both sites, with an average fractional bias of -2.6%. The model is found to correctly predict the hourly surface state, wet or dry, 85% of the time. From the 18 periods modelled using the coupled model an average absolute fractional bias of 15% for PM10 concentrations was found. Similarly the model predicts the 90'th daily mean percentiles of PMio with an average absolute bias of 19% and an average correlation (R-2) of 0.49. When surface moisture is not included in the modelling then this average correlation is reduced to 0.16, demonstrating the importance of the surface moisture conditions. Tests have been carried out to assess the sensitivity of the model to model parameters and input data. The model provides a useful tool for air quality management and for improving our understanding of non-exhaust traffic emissions.
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| 14. |
- Dutcher, Dabrina D., et al.
(author)
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Emissions from soy biodiesel blends: A single particle perspective
- 2011
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In: Atmospheric Environment. - : Elsevier BV. - 1352-2310. ; 45:20, s. 3406-3413
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Journal article (peer-reviewed)abstract
- Biodiesel has recently reemerged as a common fuel. However, emissions from biodiesel combustion have been studied in much less detail than those from traditional petroleum-based diesel. In this experiment, emissions from the combustion of different fuel blends (BOO, B02, B20, B99, where the number after B indicates the percentage, by volume, of biodiesel in the fuel) in a VW TDi engine were analyzed by aerosol time-of-flight mass spectrometers (ATOFMS) for single-particle composition and vacuum aerodynamic size. The ATOFMS results show that the PAH molecular weight distribution is not significantly affected by the fuel composition, and that sulfates are reduced by increased biodiesel content. Octanedioic acid (a carbonyl species) is increased with increased biodiesel concentration. Clustering results from the single-particle spectra show that the particles fall in five main types by chemical composition. The aerodynamic size distribution of these individual clusters was also determined. These results also show that methods used to identify diesel particle emissions for source apportionment are not applicable when significant concentrations of biodiesel are used in fuels. (C) 2011 Elsevier Ltd. All rights reserved.
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| 15. |
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| 16. |
- Fischer, Andreas, et al.
(author)
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Ozone removal by occupants in a classroom
- 2013
-
In: Atmospheric Environment. - : Elsevier BV. - 1352-2310 .- 1873-2844. ; 81, s. 11-17
-
Journal article (peer-reviewed)abstract
- Ozone concentrations were measured in a classroom with and without occupants, with the purpose to quantify effects on indoor O3 concentrations. The teacher and 24 11-year old pupils each removed O3 at a rate, first order in O3, corresponding to a rate constant of (2.5±0.6)×10-5s-1 in the present locality and to a deposition velocity of 0.45cms-1. The O3-removal caused by the occupants was approximately 2.6 times larger than that of the available surfaces belonging to the classroom and its furniture. Observation of 6-methyl-5-hepten-2-one and 4-oxopentanal at maximum concentrations of 0.2ppb and 0.7ppb, respectively, suggested squalene from human skin oil as a reactive, ozone-consuming substance. There are indications of a source of 4-oxopentanal in the classroom, even some time after the pupils left for the day. The work presented is important for a proper description of indoor exposure, both to ozone itself and some of its reaction products when trying to quantify relations between exposure and health effects.
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| 17. |
- Fridell, Erik, et al.
(author)
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A modelling study of the impact on air quality and health due to theemissions from E85 and petrol fuelled cars in Sweden
- 2014
-
In: Atmospheric Environment. - : Elsevier. - 1352-2310 .- 1873-2844. ; 82, s. 1-8
-
Journal article (peer-reviewed)abstract
- Alternative fuels are becoming more and more important for road traffic and one fuel that has been usedfor several years is ethanol (E85). The main discussion points regarding the environmental performancefor ethanol as a fuel are related to the production. However, there are also some notable differences inthe emissions between E85 and petrol fuelled vehicles. This relates to some extent to the emissions ofnitrogen oxides (NOx) and particulate matter (PM) but mainly to the composition of the emitted organiccompounds. In the present study two fuel scenarios for passenger cars are investigated for the VästraGötaland Region in Sweden; one where the cars with Otto engines run on petrol and one where they runon E85. Two emission scenarios for 2020 are constructed for the whole Europe and coupled dispersionchemistrymodelling is applied to obtain the population exposure to key pollutants. The differencesobtained from the modelling show decreased levels of NOx, ozone and benzene with E85 and increasedlevels of acetaldehyde in the Västra Götaland Region. For the latter the increase may be up to 80%, whileNOx and ozone show decreases of up to a few per cent and a few tenths of per cent, respectively.Exposure to the different air pollutants is calculated as population-weighted concentrations. The healthrisk assessment, using the calculated exposure and published exposureeresponse functions for therelevant pollutants, shows decreased health risks in the E85 scenario relative the all-petrol scenario, dueto the decreased NOx exposure, correlated with both preterm deaths and asthma. However, NOx (andNO2) may partly be indicators of unmeasured causal exhaust components in the epidemiological studiesand thus the exposureeresponse functions for these may not be applicable in the present case wherethere is a difference in NOx exposure but not a proportional difference in exposure to other exhaustcomponents normally associated with NOx. Smaller effects are expected from the changes in ozone,acetaldehyde, PM2.5 and benzene exposure. The overall difference is about 1.6 preterm deaths per yearfor the Västra Götaland Region, with lower values for the E85 scenario, when the uncertain differencesdue to the differences in NOx exposure are not considered.
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| 18. |
- Grundström, Maria, 1979, et al.
(author)
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Urban NO2 and NO pollution in relation to the North Atlantic Oscillation NAO
- 2011
-
In: Atmospheric Environment. - : Elsevier BV. - 1352-2310. ; 45:4, s. 883-888
-
Journal article (peer-reviewed)abstract
- The North Atlantic Oscillation (NAO), a measure of the strength of the zonal wind across the North Atlantic Ocean, strongly influences weather conditions in NW Europe, e.g. temperature, precipitation and wind, especially during winter. It was hypothesised that elevated concentrations of nitrogen oxides in Gothenburg would be enhanced during negative NAO index (NAOI) conditions, representing more anticyclonic weather situations and thus leading to limited air mixing in the urban atmosphere, than situations with NAOI > 0. Hourly wintertime (DecembereFebruary) concentrations (1997e2006) of NO2, NO, air pressure, temperature and wind direction from an urban rooftop (30mabove street level) in the centre of the City of Gothenburg were analysed in relation to NAOI. Air pressure, the average concentration of nitrogen oxides (NOx ¼ NO2 þ NO), as well as the fraction of hourly NO2 and NO concentrations exceeding 90 mg m_3 and the fraction of daily NO concentrations exceeding 60 mg m_3, were significantly and negatively related to NAOI. Air temperature was positively correlated with NAOI. Southerly and westerly winds were more common in months with positive NAOI, while easterly and northerly winds were overrepresented in months with negative NAOI. High pollution concentrations dominantly occurred in situations with northerly and easterly wind directions. High NO2 and NO concentrations were associated with negative NAOI, especially in the morning when the traffic rush coincided with restricted air mixing. Over the tenyear period there were trends for more negative NAOI and increased time fractions with hourly NO2 concentrations exceeding 90 mgm_3. The conclusion of this study is that a climate shift towards higher or lower NAOI has the potential to significantly influence urban air pollution in North-West Europe, and thus the possibility to reach air quality standards, even if emissions remain constant.
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| 19. |
- Hagerman, Inger, et al.
(author)
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Effects on heart rate variability by artificially generated indoor nano-sized particles in a chamber study
- 2014
-
In: Atmospheric Environment. - : Elsevier BV. - 1352-2310. ; 88, s. 165-171
-
Journal article (peer-reviewed)abstract
- Background: Airborne particles are associated with increased morbidity and mortality due to respiratory and cardiovascular diseases in polluted areas. There is a growing interest in nano-sized particles with diameter < 100 nm and their potential health effects. Heart rate variability (HRV) is a noninvasive method for cardiovascular risk prediction in high prevalent groups. Aim of study: The aim was to evaluate the impact of nano-sized indoor air particles on HRV for healthy and adult females. Methods: All exposures were performed as controlled chamber experiments with particle exposure from burning candles, terpene + ozone reactions or filtered air in a double-blind cross over design. Twenty-two healthy females were investigated during 10 min periods at different exposures and the reactivity in high frequency (HF) spectral band of HRV were computed. Results: Heart rate was unchanged from baseline values in all groups during all experimental settings. HF power of HRV tended to increase during exposure to particles from burning candle while particles from terpene + ozone reactions tended to decrease HF power. Conclusions: Exposure to nano-sized particles of burning candles or terpene + ozone reactions results in different patterns of heart rate variability, with signs of altered autonomic cardiovascular control. Practical implications: This study indicates that the HRV method may be used for information on physiological responses of exposure to different nano-sized particles and contribute to the understanding of mechanisms behind health effects of particle exposures. (C) 2014 The Authors. Published by Elsevier Ltd.
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| 20. |
- Heimdal Nilsson, Elna, et al.
(author)
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Re-evaluation of the reaction rate coefficient of CH3Br + OH with implications for the atmospheric budget of methyl bromide
- 2013
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In: Atmospheric Environment. - : Elsevier BV. - 1352-2310. ; 80, s. 70-74
-
Journal article (peer-reviewed)abstract
- The reaction rate coefficient k(CH3Br + OH) has been determined in the temperature range 298-373 K, using pulse radiolysis/UV kinetic spectroscopy, and at 298 K using a relative rate method. The Arrhenius expression obtained from a fit to the experimental results is (2.9 +/- 0.9) x 10(-12) exp(-(1230 +/- 125)/T) cm(3) molecule(-1) s(-1), which is greater than the expression currently recommended. The relative rate experiments give k(298 K) = (4.13 +/- 0.63) x 10(-14) cm(3) molecule(-1) s(-1). The results of the absolute and relative rate experiments indicate that the source budget of atmospheric CH3Br should be reinvestigated, as was recently done for CH3Cl. (C) 2013 Elsevier Ltd. All rights reserved.
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