| 1. |
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| 2. |
- Almstrand, Ann-Charlotte, et al.
(författare)
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Airway monitoring by collection and mass spectrometric analysis of exhaled particles.
- 2009
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Ingår i: Analytical chemistry. - : American Chemical Society (ACS). - 1520-6882 .- 0003-2700. ; 81:2, s. 662-8
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Tidskriftsartikel (refereegranskat)abstract
- We describe a new method for simultaneously collecting particles in exhaled air for subsequent chemical analysis and measuring their size distribution. After forced exhalation, particles were counted and collected in spots on silicon wafers with a cascade impactor. Several phospholipids were identified by time-of-flight secondary ion mass spectrometric analysis of the collected spots, suggesting that the particles originated from the lower airways. The amount of particles collected in ten exhalations was sufficient for characterizing the phospholipid composition. The feasibility of the technique in respiratory research is demonstrated by analysis of the phospholipid composition of exhaled particles from healthy controls, patients with asthma, and patients with cystic fibrosis. We believe this technology will be useful for monitoring patients with respiratory disease and has a high potential to detect new biomarkers in exhaled air.
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| 3. |
- Almstrand, Ann-Charlotte, et al.
(författare)
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Effect of Airway Opening on Production of Exhaled Particles.
- 2010
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Ingår i: Journal of applied physiology. - : American Physiological Society. - 1522-1601 .- 8750-7587. ; 108:3, s. 584-588
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Tidskriftsartikel (refereegranskat)abstract
- The technique of sampling exhaled air is attractive because it is non-invasive, and so allows repeated sampling with ease and no risk for the patient. Knowledge of the biomarkers' origin is important in order to correctly understand and interpret the data. Endogenous particles, formed in the airways, are exhaled and reflect chemical composition of the respiratory tract lining fluid. However, the formation mechanisms and formation sites of these particles are unknown. We hypothesize that airway opening following airway closure cause production of airborne particles that are exhaled. The objective of this study was to examine production of exhaled particles following varying degrees of airway closure. 10 healthy volunteers performed 3 different breathing manoeuvres in which the initial lung volume preceding an inspiration to total lung capacity was varied between functional residual capacity (FRC) and residual volume (RV). Exhaled particle number concentrations in the size interval 0.30-2.0 mum were recorded. Number concentrations of exhaled particles showed a 2-18 fold increase after exhalations to RV compared to exhalations where no airway closure was shown (8500 (810-28000) vs. 1300 (330-13000) particles/expired litre, p=0.012). The difference was most noticeable for the smaller size range of particles (<1 mum). There were significant correlations between particle concentrations for the different manoeuvres. Our results show that airway reopening following airway closure is an important mechanism for formation of endogenous exhaled particles and that these particles originate from the terminal bronchioles. Key words: exhaled particles, airway closure, breath.
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| 4. |
- Bake, Björn, 1939, et al.
(författare)
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Exhaled Particles After a Standardized Breathing Maneuver
- 2017
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Ingår i: Journal of Aerosol Medicine and Pulmonary Drug Delivery. - : Mary Ann Liebert Inc. - 1941-2711 .- 1941-2703. ; 30:4, s. 267-273
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Tidskriftsartikel (refereegranskat)abstract
- Background: Particles in exhaled air (PEx) provide samples of respiratory tract lining fluid from small airways and offer a new opportunity to monitor pathological changes. The exhaled particles are produced by reopening of closed small airways and contain surfactant. The amount of PEx varies by orders of magnitude among subjects. A standardized breathing pattern reduces the variation, but it remains large and the reasons are unknown. The aim of the present study was to assess to what extent sex, age, body size, and spirometry results explain the interindividual variation of PEx among healthy middle-aged subjects. Methods: The PExA((R)) instrument was used to measure PEx in 126 healthy middle-aged nonsmoking subjects participating in the European Respiratory Community Health Survey (ERCS-III). The subjects performed a standardized breathing maneuver involving expiration to residual volume, a breath-hold of 3 seconds, a full inspiration, and then a full expiration into the PExA instrument. PEx number concentrations were expressed per exhalation and per exhaled liter. Age and anthropometric and spirometric variables were analyzed as potential predictors. Results: PEx/L was consistently and negatively associated to lung size-related variables and accordingly lower in men than in women. PEx/Exhalation was similar in women and men. Increasing age was associated with increasing PEx. Reference equations are presented based on age, weight, and spirometry variables and independent of sex. These predictors explained 28%-29% of the interindividual variation. Conclusions: The interindividual variation of PEx after a standardized breathing maneuver is large and the considered predictors explain a minor part only.
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| 5. |
- Bake, Björn, 1939, et al.
(författare)
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Exhaled particles and small airways
- 2019
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Ingår i: Respiratory Research. - : Springer Science and Business Media LLC. - 1465-993X. ; 20
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Tidskriftsartikel (refereegranskat)abstract
- BackgroundOriginally, studies on exhaled droplets explored properties of airborne transmission of infectious diseases. More recently, the interest focuses on properties of exhaled droplets as biomarkers, enabled by the development of technical equipment and methods for chemical analysis. Because exhaled droplets contain nonvolatile substances, particles is the physical designation. This review aims to outline the development in the area of exhaled particles, particularly regarding biomarkers and the connection with small airways, i e airways with an internal diameter<2mm.Main bodyGeneration mechanisms, sites of origin, number concentrations of exhaled particles and the content of nonvolatile substances are studied. Exhaled particles range in diameter from 0.01 and 1000m depending on generation mechanism and site of origin. Airway reopening is one scientifically substantiated particle generation mechanism. During deep expirations, small airways close and the reopening process produces minute particles. When exhaled, these particles have a diameter of <4m. A size discriminating sampling of particles <4m and determination of the size distribution, allows exhaled particle mass to be estimated. The median mass is represented by particles in the size range of 0.7 to 1.0m. Half an hour of repeated deep expirations result in samples in the order of nanogram to microgram. The source of these samples is the respiratory tract ling fluid of small airways and consists of lipids and proteins, similarly to surfactant. Early clinical studies of e g chronic obstructive pulmonary disease and asthma, reported altered particle formation and particle composition.ConclusionThe physical properties and content of exhaled particles generated by the airway reopening mechanism offers an exciting noninvasive way to obtain samples from the respiratory tract lining fluid of small airways. The biomarker potential is only at the beginning to be explored.
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| 6. |
- Bredberg, Anna, et al.
(författare)
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Analysis of manganese and iron in exhaled endogenous particles
- 2014
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Ingår i: Journal of Analytical Atomic Spectrometry. - 0267-9477 .- 1364-5544. ; 29, s. 730-735
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Tidskriftsartikel (refereegranskat)abstract
- Background: Many full-time welders experience some sort of respiratory disorder e.g., asthma, bronchitis and metal fume fever. Thus, welding aerosols are thought to cause airway inflammation. There is a need for markers of welding aerosols in exposure assessments, and as most welding aerosols contain manganese and iron, these metals may possibly be used as an indicator. We have previously developed a novel non-invasive technique to collect endogenous particles in exhaled air (PEx). This study is designed to i) develop a method for analysis of manganese and iron in PEx and ii) investigate whether the manganese and/or iron content of PEx changes after exposure to welding aerosols. Methods: Nine individuals were experimentally exposed to welding fumes. PEx was collected at three time points for each individual; before, after and 24 hour after exposure. Analyses of PEx samples were performed using Inductively Coupled Plasma Mass Spectrometry (ICP-MS). Results: Four out of nine individuals showed an increase in manganese and iron levels after exposure to welding aerosols. The mean manganese and iron concentration increased from,
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| 7. |
- Emanuelsson, Eva U., et al.
(författare)
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Influence of Humidity, Temperature, and Radicals on the Formation and Thermal Properties of Secondary Organic Aerosol (SOA) from Ozonolysis of β-Pinene
- 2013
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Ingår i: Journal of Physical Chemistry A. - : American Chemical Society (ACS). - 1089-5639 .- 1520-5215. ; 117:40, s. 10346-10358
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Tidskriftsartikel (refereegranskat)abstract
- The influence of water and radicals on SOAs produced by β-pinene ozonolysis was investigated at 298 and 288 K using a laminar flow reactor. A volatility tandem differential mobility analyzer (VTDMA) was used to measure the evaporation of the SOA, enabling the parametrization of its volatility properties. The parameters extracted included the temperature at which 50% of the aerosol had evaporated (TVFR0.5) and the slope factor (SVFR). An increase in SVFR indicates a broader distribution of vapor pressures for the aerosol constituents. Reducing the reaction temperature increased SVFR and decreased TVFR0.5 under humid conditions but had less effect on TVFR0.5 under dry conditions. In general, higher water concentrations gave lower TVFR0.5 values, more negative SVFR values, and a reduction in total SOA production. The radical conditions were changed by introducing OH scavengers to generate systems with and without OH radicals and with different [HO2]/[RO2] ratios. The presence of a scavenger and lower [HO2]/[RO2] ratio reduced SOA production. Observed changes in SVFR values could be linked to the more complex chemistry that occurs in the absence of a scavenger and indicated that additional HO2 chemistry gives products with a wider range of vapor pressures. Updates to existing ozonolysis mechanisms with routes that describe the observed responses to water and radical conditions for monoterpenes with endocyclic and exocyclic double bonds are discussed.
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| 8. |
- Emilsson, Össur Ingi, et al.
(författare)
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Respiratory symptoms, sleep-disordered breathing and biomarkers in nocturnal gastroesophageal reflux
- 2016
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Ingår i: Respiratory Research. - : Springer Science and Business Media LLC. - 1465-993X .- 1465-9921. ; 17
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Tidskriftsartikel (refereegranskat)abstract
- Background: Nocturnal gastroesophageal reflux (nGER) is associated with respiratory symptoms and sleep-disordered breathing (SDB), but the pathogenesis is unclear. We aimed to investigate the association between nGER and respiratory symptoms, exacerbations of respiratory symptoms, SDB and airway inflammation. Methods: Participants in the European Community Respiratory Health Survey III in Iceland with nGER symptoms (n = 48) and age and gender matched controls (n = 42) were studied by questionnaires, exhaled breath condensate (EBC), particles in exhaled air (PEx) measurements, and a home polygraphic study. An exacerbation of respiratory symptoms was defined as an episode of markedly worse respiratory symptoms in the previous 12 months. Results: Asthma and bronchitis symptoms were more common among nGER subjects than controls (54 % vs 29 %, p = 0.01; and 60 % vs 26 %, p < 0.01, respectively), as were exacerbations of respiratory symptoms (19 % vs 5 %, p = 0.04). Objectively measured snoring was more common among subjects with nGER than controls (snores per hour of sleep, median (IQR): 177 (79-281) vs 67 (32-182), p = 0.004). Pepsin (2.5 ng/ml (0.8-5.8) vs 0.8 ng/ml (0.8-3.6), p = 0.03), substance P (741 pg/ml (626-821) vs 623 pg/ml (562-676), p < 0.001) and 8-isoprostane (3.0 pg/ml (2.7-3.9) vs 2.6 pg/ml (2.2-2.9), p = 0.002) in EBC were higher among nGER subjects than controls. Albumin and surfactant protein A in PEx were lower among nGER subjects. These findings were independent of BMI. Conclusion: In a general population sample, nGER is associated with symptoms of asthma and bronchitis, as well as exacerbations of respiratory symptoms. Also, nGER is associated with increased respiratory effort during sleep. Biomarker measurements in EBC, PEx and serum indicate that micro-aspiration and neurogenic inflammation are plausible mechanisms.
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| 9. |
- Fischer, Andreas, et al.
(författare)
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Chemistry and indoor air quality in a multi-storey wooden passive (low energy) building : Formation of peroxyacetyl nitrate
- 2014
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Ingår i: Indoor + Built Environment. - : SAGE Publications Ltd. - 1420-326X .- 1423-0070. ; 23:3, s. 485-496
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Tidskriftsartikel (refereegranskat)abstract
- Indoor air measurements were conducted in one unoccupied apartment of a 'near-zero-energy' residential building with a unique, wooden construction. Ozone, NO2, fine particles and volatile organic compounds, formaldehyde, acetaldehyde and peroxyacetyl nitrate (PAN) were measured under 'as is' conditions and after intentional intervention by adding ozone to simulate an ambient air ozone episode. Undisturbed concentrations were: O 3 5-10 ppb, NO2 5-8 ppb, fine particles 2000-5000 cm -3, formaldehyde 35 ± 5 μg/m3, PAN 0.3 ppb. During intervention, O3 was 50-60 ppb, NO2 15-20 ppb, fine particles 20,000-25,000 cm-3, formaldehyde 44 ± 2 μg/m3 and PAN 0.7-1 ppb. It was shown that chemical reactions had taken place in the indoor air. Ozone-initiated chemistry produced various aldehydes, PAN and, as a direct response to increased ozone concentrations, also fine particles. Calculations made by a simple model of PAN formation showed that an air change rate of around 0.2 h-1 would provide optimum conditions for PAN formation in a setting comparable to that of the investigated apartment. This air change rate is well below the Swedish national minimum of 0.5 h-1. Further, the calculations show that the non-photochemical PAN formation could be a consequence of mixing ozone and nitrogen dioxide with terpenes and acetaldehyde.
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| 10. |
- Fischer, Andreas, et al.
(författare)
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Ozone removal by occupants in a classroom
- 2013
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Ingår i: Atmospheric Environment. - : Elsevier BV. - 1352-2310 .- 1873-2844. ; 81, s. 11-17
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Tidskriftsartikel (refereegranskat)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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| 11. |
- Fischer, Andreas, et al.
(författare)
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Ventilation strategies and indoor particulate matter in a classroom
- 2015
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Ingår i: Indoor Air. - : Hindawi Limited. - 0905-6947 .- 1600-0668. ; 25:2, s. 168-175
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Tidskriftsartikel (refereegranskat)abstract
- Particle mass and number concentrations were measured in a mechanically ventilated classroom as part of a study of ventilation strategies for energy conservation. The ventilation system was operated either continuously, intermittently, or shut down during nights while it was on during workdays. It appears that the nighttime ventilation scheme is not important for indoor particle concentrations the following day if fans are operated to give five air exchanges in advance of the workday. The highest concentrations of PM10 were found during and after workdays and were due to human activity in the classroom. The average workday PM10 concentration was 14g/m(3), well below the WHO guideline values. The number concentration of particles with diameter <0.750m was typically between 0.5x10(3) and 3.5x10(3)particle/cm(3). These concentrations were largely independent of the occupants. Transient formation of small particles was observed when ventilation was shut down. Then remaining ozone reacted with terpenes emitted by indoor sources and gave up to 8x10(3)particle/cm(3) before formation stopped due to lack of ozone. The intermittent ventilation regime was found least favorable for the indoor air quality in the classroom.
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| 12. |
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| 13. |
- Hak, Claudia S., 1976, et al.
(författare)
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A new approach to in-situ determination of roadside particle emission factors of individual vehicles under conventional driving conditions
- 2009
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Ingår i: Atmospheric Environment. - : Elsevier BV. - 1352-2310. ; 43:15, s. 2481-2488
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Tidskriftsartikel (refereegranskat)abstract
- A method for continuous on-road measurements of particle number emissions for both diesel- and petrol-fuelled vehicles is presented. The setup allows the determination of particle number emission factors on an individual vehicle basis by the simultaneous measurement of CO2 and particle concentrations. As an alternative to previous measurements on the kerbside, the sample is taken directly in the street, with the advantage of sampling in-situ within the exhaust plumes of passing vehicles, allowing the separation of the individual high-concentration plumes. The method was tested in two experiments that were conducted in the Gothenburg area. In the first study, which was performed at an urban roadside, we were able to determine particle emission factors from individual vehicles in a common car fleet passing the measurement site. The obtained emission factors were of the same order of magnitude (between 1.4 × 1012 and 1.8 × 1014 particles km−1) as values published in the recent literature for light duty vehicles. An additional on-road experiment was conducted at a rural road with four light duty reference vehicles (three of them petrol-powered and one diesel-powered) at driving speeds of 50 and 70 km h−1, realised with different engine speeds. The results of the traffic emission studies show that the method is applicable provided that instruments with an adequate dynamic range are used and that the traffic is not too dense. In addition, the variability in particle emissions for a specified driving condition was estimated.
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| 14. |
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| 15. |
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| 16. |
- Holmgren, Helene, 1981, et al.
(författare)
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Effects of breath holding at low and high lung volumes on amount of exhaled particles
- 2013
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Ingår i: Respiratory Physiology & Neurobiology. - : Elsevier BV. - 1569-9048 .- 1878-1519. ; 185:2, s. 228-234
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Tidskriftsartikel (refereegranskat)abstract
- Exhaled breath contains particles originating from the respiratory tract lining fluid. The particles are thought to be generated during inhalation, by reopening of airways closed in the preceding expiration. The aim here was to explore processes that control exhaled particle concentrations. The results show that 5 and 10 s breath holding at residual volume increased the median concentration of particles in exhaled air by 63% and 110%, respectively, averaged over 10 subjects. An increasing number of closed airways, developing on a timescale of seconds explains this behaviour. Breath holds of 5, 10 and 20 s at total lung capacity decreased the concentration to 63%, 45% and 28% respectively, of the directly exhaled concentration. The decrease in particle concentration after breath holding at total lung capacity is caused by gravitational settling in the alveoli and associated bronchioles. The geometry employed here when modelling the deposition is however not satisfactory and ways of improving the description are discussed.
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| 17. |
- Holmgren, Helene, 1981, et al.
(författare)
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Influence of Film Dimensions on Film Droplet Formation
- 2011
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Background: Aerosol particles may be generated from rupturing liquid films through a droplet formation mechanism. The present work was undertaken with the aim to throw some light on the influence of film dimensions on droplet formation with possible consequences for exhaled breath aerosol formation. Methods: The film droplet formation process was mimicked by using a purpose-built device, where fluid films were spanned across holes of known diameters. As the films burst, droplets were formed and the number and size distributions of the resulting droplets were determined. Results: No general relation could be found between hole diameter and the number of droplets generated per unit surface area of fluid film. Averaged over all film sizes, a higher surface tension yielded higher concentrations of droplets. Surface tension did not influence the resulting droplet diameter, but it was found that smaller films generated smaller droplets. Conclusions: This study shows that small fluid films generate droplets as efficiently as large films and that droplets may well be generated from films with diameters below 1 mm. This has implications for the formation of film droplets from reopening of closed airways since human terminal bronchioles are of similar dimensions. Thus, the results provide support for the earlier proposed mechanism where reopening of closed airways is one origin of exhaled particles.
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| 18. |
- Holmgren, Helene, 1981, et al.
(författare)
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Influence of film dimensions on film droplet formation.
- 2012
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Ingår i: Journal of aerosol medicine and pulmonary drug delivery. - : Mary Ann Liebert Inc. - 1941-2703 .- 1941-2711. ; 25:1, s. 47-53
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Tidskriftsartikel (refereegranskat)abstract
- Abstract Background: Aerosol particles may be generated from rupturing liquid films through a droplet formation mechanism. The present work was undertaken with the aim to throw some light on the influence of film dimensions on droplet formation with possible consequences for exhaled breath aerosol formation. Methods: The film droplet formation process was mimicked by using a purpose-built device, where fluid films were spanned across holes of known diameters. As the films burst, droplets were formed and the number and size distributions of the resulting droplets were determined. Results: No general relation could be found between hole diameter and the number of droplets generated per unit surface area of fluid film. Averaged over all film sizes, a higher surface tension yielded higher concentrations of droplets. Surface tension did not influence the resulting droplet diameter, but it was found that smaller films generated smaller droplets. Conclusions: This study shows that small fluid films generate droplets as efficiently as large films, and that droplets may well be generated from films with diameters below 1mm. This has implications for the formation of film droplets from reopening of closed airways because human terminal bronchioles are of similar dimensions. Thus, the results provide support for the earlier proposed mechanism where reopening of closed airways is one origin of exhaled particles.
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| 19. |
- Holmgren, Helene, 1981, et al.
(författare)
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Relation Between Humidity and Size of Exhaled Particles
- 2011
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Ingår i: Journal of Aerosol Medicine and Pulmonary Drug Delivery. - : Mary Ann Liebert Inc. - 1941-2711 .- 1941-2703. ; 24:5, s. 253-260
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Tidskriftsartikel (refereegranskat)abstract
- Background: Aerosol particles are generated in human airways, and leave the body with exhaled air. These particles may carry indicators of various lung conditions. To fully utilize the information provided by endo- genously produced exhaled particles, it is important to understand their formation mechanism and physical properties. The scope of this work was to measure number size distributions of exhaled aerosol particles at various surrounding relative humidities (RH) in order to gain some knowledge of the size distribution at the point of particle generation. Methods: Number size distributions of exhaled particles were measured at various RHs, using an optical particle counter. Breathing with airway closure was employed. Results: A relation between particle volume and RH was fitted to experimental data and used to predict how exhaled droplets behave at RHs not easily accessible by experiments. The diameter of an exhaled particle is reduced by a factor of 0.42 when the RH is changed from 99.5 to 75% at 309 K. Calculations also show that the droplets are concentrated solutions near saturation at 75% RH. Conclusions: It is concluded that the particles are supersaturated liquid particles, rather than crystalline solids, in ambient air with RH below 75%. A size distribution related to the aerosol at the moment of formation is given. A successful detailed formation mechanismshould be able to accommodate the size distribution predicted at 99.5%RH.
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| 20. |
- Holmgren, Helene, 1981, et al.
(författare)
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Size Distribution of Exhaled Particles in the Range from 0.01 to 2.0 µm
- 2010
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Ingår i: Journal of Aerosol Science. - : Elsevier BV. - 0021-8502 .- 1879-1964. ; 41:5, s. 439-446
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Tidskriftsartikel (refereegranskat)abstract
- This study investigates the number size distribution of endogenously produced exhaled particles during tidal breathing and breathing with airway closure. This is the first time that the region below 0.4 µm has been investigated. The particle concentration was generally lower for tidal breathing than for airway closure, although the inter-individual variation was large. During tidal breathing, the size distribution peaks at around 0.07 µm. This peak is still present during the airway closure manoeuvre, but an additional broad and strong peak is found between 0.2 and 0.5 µm. This suggests that different mechanisms govern the generation of particles in the two cases. The particles produced from airway closure may be attributed to formation of film droplets in the distal bronchioles during inhalation. It is speculated that the very small particles are film droplets originating from the alveolar region.
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| 21. |
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| 22. |
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| 23. |
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| 24. |
- Jerksjö, Martin, et al.
(författare)
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Simultaneous measurements of gaseous emissions, particulates and noise from individual vehicles in traffic
- 2007
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- In order to identify vehicles and traffic situations that have a negative impact on the environment, it is important to be able to measure emissions from individual vehicles in traffic. In this study an attempt is made to measure gases, particles and noise emitted from single vehicles in normal traffic. An apparatus for Fuel Efficiency Automobile Test (FEAT), by which emissions of NO, CO, HC and CO2 are measured, was combined with particle instruments for both total and size-distribution measurements, as well as noise measurements. The sampling of particles was done utilising a tube system for sampling on the road together with a dilution system. The noise measurements were done with two microphones at different heights. The measurements show that it is feasible to study regulated emissions, particle emissions and noise emissions from individual vehicles in normal traffic. Noise data was collected from ca 200 individual vehicles during the measurement campaign and the emissions of some of the vehicles were evaluated. The measurements were manually supervised and the evaluations mainly made by hand. The experiences of this project are encouraging and show that it is possible to perform measurements of noise emissions from individual vehicles automatically. One way to achieve this would be by extending the FEAT system so that it also measures noise emission. Further it is important to perform sampling and evaluation automatically and to use computerized procedures for the evaluation. By using CO2 data together with the particle data, we were able to obtain PM emission factors for individual vehicles. We also showed that the particle size-distribution can be obtained from individual vehicles in traffic when using a fast instrument. This also, in principle, allows for the separation of particles emitted from the engine and particles from road and tyre wear.
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| 25. |
- Jonsson, Åsa M., 1976, et al.
(författare)
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Impact of humidity on the ozone initiated oxidation of limonene, delta3-carene, and alpha-pinene.
- 2006
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Ingår i: Environmental science & technology. - : American Chemical Society (ACS). - 0013-936X .- 1520-5851. ; 40:1, s. 188-94
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Tidskriftsartikel (refereegranskat)abstract
- The effect of water on the initial secondary organic aerosol (SOA) formation from gas-phase ozonolysis of limonene, delta3-carene, and alpha-pinene (-3 and approximately 1.5 x 10(11) molecule cm(-3) reacted) has been investigated in a flow reactor at controlled relative humidity (RH), temperature (298 +/- 0.4 K), and reaction time (270 +/- 2 s). Low amounts of terpene converted minimize the impact of secondary reactions. A comparison of the SOA formation from the three terpenes was made for initial rate of reactions being around 7.5 x 10(8) and 15 x 10(8) molecule cm(-3) s(-1). The most efficient species in producing SOA was limonene, while alpha-pinene was the least efficient. The results showed that an enhancement in water vapor concentration (<2-85% RH) caused an increase in both integrated mass (M10-300nm) and total number (N10-300nm). The effect on number and mass were a factor of 2-3 and 4-8, respectively. Physical water up-take can partly explain the increase in mass, but not the observed increase in number. Therefore it was concluded that the increase in water concentration must, by a gas-phase reaction, produce more low volatility product(s).
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| 26. |
- Jonsson, Åsa M., 1976, et al.
(författare)
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Influence of OH Scavenger on the Water Effect on Secondary Organic Aerosol Formation from Ozonolysis of Limonene, Δ3-Carene, and α-Pinene
- 2008
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Ingår i: Environ. Sci. Technol. - : American Chemical Society (ACS). ; 42:16, s. 5938-5944
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Tidskriftsartikel (refereegranskat)abstract
- The effect of OH scavengers on how water vapor influences the formation of secondary organic aerosol (SOA) in ozonolysis of limonene, Δ3-carene, and α-pinene at low concentrations has been investigated by using a laminar flow reactor. Cyclohexane and 2-butanol (3−40 × 1013 molecules cm−3) were used as scavengers and compared to experiments without any scavenger. The reactions were conducted at 298 K and at relative humidities between <10 and 80%. The yield of SOA decreased in the order “no scavenger” > 2-butanol > cyclohexane. The effect of water vapor was similar for 2-butanol and without a scavenger, with an increase in particle number and mass concentration with increasing relative humidity. The water effect for cyclohexane was more complex, depending on the terpene, scavenger concentration, and SOA concentration. The water effect seems to be influenced by the HO2/RO2 ratio. The results are discussed in relation to the currently suggested mechanism for alkene ozonolysis and to atmospheric importance. The results imply that the ozone-initiated oxidation of terpenes needs revision in order to fully account for the role of water in the chemical mechanism.
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| 27. |
- Jonsson, Åsa M., 1976, et al.
(författare)
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The Effect of Temperature and Water on Secondary Organic Aerosol Formation from Ozonolysis of Limonene, D3-carene and a-pinene
- 2008
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Ingår i: Atmos. Chem. Phys.. ; 8, s. 6541-6549
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Tidskriftsartikel (refereegranskat)abstract
- The effect of reaction temperature and how water vapour influences the formation of secondary organic aerosol (SOA) in ozonolysis of limonene, 13-carene and -pinene, both regarding number and mass of particles, has been investigated by using a laminar flow reactor (G-FROST). Experiments with cyclohexane and 2-butanol as OH scavengers were compared to experiments without any scavenger. The reactions were conducted in the temperature range between 298 and 243 K, and at relative humidities between <10 and 80%. Results showed that there is still a scavenger effect on number and mass concentrations at low temperatures between experiments with and without an addition of an OH scavenger. This shows that the OH chemistry is influencing the SOA formation also at these temperatures. The overall temperature dependence on SOA formation is not as strong as expected from partitioning theory. In some cases there is even a positive temperature dependence that must be related to changes in the chemical mechanism and/or reduced rates of secondary chemistry at low temperatures. The precursor’s -pinene and 13-carene exhibit a similar temperature dependence regarding both number and mass of particles formed, whereas limonene shows a different dependence. The water effect at low temperature could be explained by physical uptake and cluster stabilisation. At higher temperatures, only a physical explanation is not sufficient and the observations are in line with water changing the chemical mechanism or reaction rates. The data presented adds to the understanding of SOA contribution to new particle formation and atmospheric degradation mechanisms.
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| 28. |
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| 29. |
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| 30. |
- Larsson, Per, et al.
(författare)
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The effect of exhalation flow on endogenous particle emission and phospholipid composition
- 2017
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Ingår i: Respiratory Physiology & Neurobiology. - : Elsevier BV. - 1569-9048. ; 243, s. 39-46
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Tidskriftsartikel (refereegranskat)abstract
- Exhaled particles constitute a micro-sample of respiratory tract lining fluid. Inhalations from low lung volumes generate particles in small airways by the airway re-opening mechanism. Forced exhalations are assumed to generate particles in central airways by mechanisms associated with high air velocities. To increase knowledge on how and where particles are formed, different breathing manoeuvres were compared in 11 healthy volunteers. Particles in the 0.41-4.55 mu m diameter range were characterised and sampled. The surfactant lipid dipalmitoylphosphatidylcholine (DPPC) was quantified by mass spectrometry. The mass of exhaled particles increased by 150% (95% CI 10-470) for the forced exhalation and by 470% (95% CI 150-1190) for the airway re-opening manoeuvre, compared to slow exhalations. DPPC weight percent concentration (wt%) in particles was 2.8 wt% (95%CI 1.4-4.2) and 9.4 wt% (95%CI 8.0-10.8) for the forced and the airway re-opening manoeuvres, respectively. In conclusion, forced exhalation and airway re-opening manoeuvres generate particles from different airway regions having different DPPC concentration.
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| 31. |
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| 32. |
- Ljungqvist, Göran, et al.
(författare)
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Biomarker for welding exposure in exhaled endogenous particles
- 2014
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Ingår i: The European respiratory journal. Supplement. - 0904-1850.
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Konferensbidrag (refereegranskat)abstract
- More than two million workers are exposed to pneumotoxic welding aerosols and there is a need for target organ specific biomarkers of exposure. Manganese is a common constituent of iron alloys, its occupational exposure limit is low and other biomarkers are poor, which makes it a good model substance. We hypothesize that metal particles are deposited in the small airways and are incorporated into endogenous particles formed during respiration. A subsequent analysis of these particles in exhaled air (PEx) can serve as a biomarker for metals in welding fumes. We have recently developed a method for the collection of PEx (Almstrand, A.-C. et al. Anal Chem 2008; 81:662-668), based on counting of the exhaled particles and subsequent collection by impaction on a filter. Here we developed a method for analysis of trace metal content, i.e. manganese and iron in PEx. The method involved desorption of the filter in 5% nitric acid and analysis of the metal content by ICP-MS. To test our hypothesis, we exposed 9 healthy non-smokers (4F/5M, 29-63 years) to welding aerosol in an exposure chamber (Isaxon, C. et al. Aerosol Sci Tech 2012; 47:52-59) for two hours. Manganese and iron was analysed in PEx samples collected before, immediately after and 24 h after exposure. The results showed that 4 out of 9 persons had substantially increased levels of both manganese and iron in PEx immediately after exposure. Before exposure two samples had an iron content above limit of detection and none of the samples collected after 24 h. Manganese was below LOD in all samples collected before and 24 h after exposure. The study showed that the analysis of metals in PEx is a promising biomarker for metal aerosol exposure.
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| 33. |
- Lärstad, Mona, 1971, et al.
(författare)
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Surfactant Protein A in Exhaled Endogenous Particles Is Decreased in Chronic Obstructive Pulmonary Disease (COPD) Patients: A Pilot Study
- 2015
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Ingår i: Plos One. - : Public Library of Science (PLoS). - 1932-6203. ; 10:12
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Tidskriftsartikel (refereegranskat)abstract
- Background Exhaled, endogenous particles are formed from the epithelial lining fluid in small airways, where surfactant protein A (SP-A) plays an important role in pulmonary host defense. Based on the knowledge that chronic obstructive pulmonary disease (COPD) starts in the small airway epithelium, we hypothesized that chronic inflammation modulates peripheral exhaled particle SP-A and albumin levels. The main objective of this explorative study was to compare the SP-A and albumin contents in exhaled particles from patients with COPD and healthy subjects and to determine exhaled particle number concentrations. Patients with stable COPD ranging from moderate to very severe (n = 13), and healthy nonsmoking subjects (n = 12) were studied. Subjects performed repeated breath maneuvers allowing for airway closure and re-opening, and exhaled particles were optically counted and collected on a membrane using the novel PExA1 instrument setup. Immunoassays were used to quantify SP-A and albumin. COPD patients exhibited significantly lower SP-A mass content of the exhaled particles (2.7 vs. 3.9 weight percent, p = 0.036) and lower particle number concentration (p<0.0001) than healthy subjects. Albumin mass contents were similar for both groups. Decreased levels of SP-A may lead to impaired host defense functions of surfactant in the airways, contributing to increased susceptibility to COPD exacerbations. SP-A in exhaled particles from small airways may represent a promising non-invasive biomarker of disease in COPD patients.
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| 34. |
- Olofson, K. Frans G., 1976, et al.
(författare)
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Urban aerosol evolution and particle formation during wintertime temperature inversions
- 2009
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Ingår i: Atmospheric Environment. - : Elsevier BV. - 1352-2310. ; 43, s. 340-346
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Tidskriftsartikel (refereegranskat)abstract
- Aerosol temporal and spatial distributions during wintertime temperature inversions in Gothenburg, Sweden, have been characterized by ground-based and airborne particle measurements combined with lidar measurements. Ground inversions frequently developed during evenings and nights with stable cold conditions, and the low wintertime insolation often resulted in near neutral boundary layer conditions during day-time. Under these conditions ground level aerosol concentrations peaked during morning rush hours and often remained relatively high throughout the day due to inefficient ventilation. The particle number concentrations decreased slowly with increasing altitude within the boundary layer, and measurements slightly above the boundary layer suggested limited entrainment of polluted air into the free troposphere. High concentrations of ultrafine particles were observed throughout the boundary layer up to altitudes of 1100 m, which suggested that nucleation took place within the residual layer during the night and early morning. Recently formed particles were also observed around midday when the layer near ground was ventilated by mixing into the boundary layer, which indicated that ultrafine particles were either transported down from the residual layer to ground level or formed when the polluted surface layer mixed with the cleaner air above.
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| 35. |
- Olofsson, Marcus, 1968, et al.
(författare)
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Application of Relaxed Eddy Accumulation Technique to Quantify Hg0 Fluxes Over Modified Soil Surfaces
- 2005
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Ingår i: Water, Air, & Soil Pollution. - : Springer Science and Business Media LLC. - 0049-6979 .- 1573-2932. ; 167:1-4, s. 331-352
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Tidskriftsartikel (refereegranskat)abstract
- Fluxes of mercury from a waste repository and from an agricultural field amended with sewage sludge were measured. The measurements were performed by utilising a Relaxed Eddy Accumulation (REA) system synchronously coupled to automated mercury cold vapour atomic fluorescence analysers (CVAFA). The waste repository was severely contaminated and fluxes of between 0.16μg m−2 h−1 and 29μg m−2 h−1 could be measured. Fluxes at the slightly contaminated agricultural field measured between 8 ng m−2 h−1 and 1.9μg m−2 h−1. The results showed that the REA-CVAFA system could be used for measurements above both severely-and slightly contaminated soils. The measurements at the chlor-alkali plant showed that temperature was the most important parameter controlling the release of mercury at this site. At the agricultural field, the measurements indicated that both solar radiation and temperature may have influenced the emissions. Most of the mercury added to the field was lost to the atmosphere during the summer season.
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| 36. |
- Olofsson, Marcus, 1968, et al.
(författare)
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The flux of isoprene from a willow coppice plantation and the effect on local air quality
- 2005
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Ingår i: Atmospheric Environment. - : Elsevier BV. - 1352-2310. ; 39:11, s. 2061-2070
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Tidskriftsartikel (refereegranskat)abstract
- Isoprene fluxes from a Salix viminalis (willow) plantation in western Sweden were measured using the relaxed eddy accumulation (REA) technique. Fluxes of up to 0.23 mu g m(-2) s(-1) could be observed. A standard emission factor at 303 K and a PAR flux of 1000 mu mol m(-2) s(-1) was estimated to 0.98 mu g m(-2) s(-1) by using the G93 algorithm. The chemistry of an air parcel passing over a willow coppice plantation was investigated utilising a Lagrangian box model in which the measured isoprene fluxes were used as input data. Dispersion after the field was accounted for by a procedure based on the Gaussian plume model. The calculations indicate that, in most cases, the isoprene emissions have a small effect on the local air quality.
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| 37. |
- Prakash, Jai, et al.
(författare)
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Characterization of Propane Fueled Flames: A Significant Source of Brown Carbon
- 2022
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Ingår i: Atmosphere. - : MDPI AG. - 2073-4433. ; 13:8
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Tidskriftsartikel (refereegranskat)abstract
- In this study, we developed a framework for interpreting the in situ morphological properties of black carbon (BC, also referred to as “soot” due to combustion relevance) mixed with primary organic aerosol. Integration of the experiment considering primary organic aerosol (POA) evaporation from the soot particles was examined using a Differential mass–mobility analyzer (DMA) and showed the untold story of the mixing of BC and POA. We also hypothesize that morphological transformation of soots and determined such as (i) the evaporation of externally and internally mixed POA led to a decline in the particle number and size of monodisperse aerosol; (ii) presence of externally mixed BC was interpreted from the occurrence of two peaks of soot upon heating; (iii) heat-induced collapse of the BC core possibly resulted from the evaporation of material from the voids and effect of heat; (iv) volume equivalent to changes in the mobility diameter represented evaporation of POA from the surface and collapse upon heating. POA constituted a high fraction (20–40% by mass) of aerosol mass from these flames and was predominantly (i.e., 92–97% by mass) internally mixed with BC. POA was found to be highly light absorptive, i.e., an Ångström absorption exponent (AAE) value of (in general) >1.5 was estimated for BC + POA at 405/781 nm wavelengths. Interestingly, a much more highly absorptive POA [mass absorption cross-section (MAC)-5 m2 g−1] at 405 nm was discovered under a specific flame setting, which was comparable to MACs of BC particles (8–9 m2 g−1).
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| 38. |
- Rupar-Gadd, Katarina, 1974-
(författare)
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Biomass Pre-treatment for the Production of Sustainable Energy : Emissions and Self-ignition
- 2006
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Organic emissions with focus on terpenes, from biomass drying and storage were investigated by Solid Phase Microextraction (SPME) and GC-FID and GC-MS. The remaining terpenes in the biomass (Spruce and pine wood chips) after drying were dependant on the drying temperature and drying medium used. The drying medium used was steam or hot air; the drying temperatures used were 140degreeC, 170degreeC and 200degreeC. Steam drying at 170degreeC left more of the terpenes remaining in the wood chips, not emitting them into the drying medium. The terpenes emitted from storage of forest residues and bark and wood chips increased up to three-four or four-five months of storage, and then dropped down to approximately the same low level as the first month. The leachate taken from the forest residue pile contained 27µg PAH per liter. The SPME response for a monoterpene (a-terpene) at different temperatures, amounts and humidities was quantified. The highest concentration calibrated was 250 ppm and the lowest 9.4 ppm. There is a better linear agreement at higher temperatures (70degreeC and 100degreeC) than lower temperatures (below 40degreeC). Organic emissions from biofuel combustion were measured at three medium sized (~ 1MW) biomass fired moving grate boilers fired with different fuels: dry wood fuel, forest residues and pellets. The PAH emissions varied by almost three orders of magnitude between the three boilers tested, 2.8-2500 microgram/m3. It was difficult to identify any general parameters correlating to the PAH emissions. The variation in PAH emission is most probably a result of boiler design and tuning of the combustion conditions. When comparing the contribution to self-heating from different wood materials by means of isothermal calorimetry with different metals added and stored at different temperatures, the differences were quite large. Some of the samples released as much as 600mW/kg, whereas others did not contribute at all to the self-heating. The storage temperature, at which the samples released the most heat, was 50C. There was a peak in heat release for most of the samples after 10-30 days. Stepwise increase in temperature did not favour the heat release in the sample Dry Mix; the heat released was even lower than when it was directly put in the different storage temperatures. When metal is added, there is an increase in heat release, the reference sample without metal released 200mW/kg compared to 600mW when copper was added.
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| 39. |
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| 40. |
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| 41. |
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| 42. |
- Watne, Ågot, 1983, et al.
(författare)
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Fresh and Oxidized Emissions from In-Use Transit Buses Running on Diesel, Biodiesel, and CNG
- 2018
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Ingår i: Environmental Science & Technology. - : American Chemical Society (ACS). - 0013-936X .- 1520-5851. ; 52:14, s. 7720-7728
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Tidskriftsartikel (refereegranskat)abstract
- The potential effect of changing to a nonfossil fuel vehicle fleet was investigated by measuring primary emissions (by extractive sampling of bus plumes) and secondary mass formation, using a Gothenburg Potential Aerosol Mass (Go:PAM) reactor, from 29 in-use transit buses. Regarding fresh emissions, diesel (DSL) buses without a diesel particulate filter (DPF) emitted the highest median mass of particles, whereas compressed natural gas (CNG) buses emitted the lowest ((EFPM)-E-Md 514 and 11 mg kg(fuel)(-1) respectively). Rapeseed methyl ester (RME) buses showed smaller (EFPM)-E-Md and particle sizes than DSL buses. DSL (no DPF) and hybrid-electric RME (RMEHEV) buses exhibited the highest particle numbers ((EFPN)-E-Md 12 X 10(14) # kg(fuel)(-1)). RMEHEv buses displayed a significant nucleation mode (D-p < 20 nm). EFPN of CNG buses spanned the highest to lowest values measured. Low (EFPN)-E-Md and (EFPM)-E-Md were observed for a DPF-equipped DSL bus. Secondary particle formation resulting from exhaust aging was generally important for all the buses (79% showed an average EFPM:AGED/EF(PM)(:FRE)s H ratio >10) and fuel types tested, suggesting an important nonfuel dependent source. The results suggest that the potential for forming secondary mass should be considered in future fuel shifts, since the environmental impact is different when only considering the primary emissions.
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| 43. |
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| 44. |
- Zhao, D. M, et al.
(författare)
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Performance study of 48 road-aged commercial three way catalytic converters
- 2006
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Ingår i: Water Air and Soil Pollution. ; 169:1-4, s. 255-273
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Tidskriftsartikel (refereegranskat)abstract
- 48 commercial three-way catalytic converters (TWC) aged on-road were investigated. The results show that there was no significant impact of aging on light off temperatures for CO, HC, and NO up to 120 000 km. Above 120 000 km, the light off temperatures in general increased. The steady state conversions for CO and HC are not significantly affected by aging. However, the steady state conversion of NO is decreased with increased mileage at the conditions studied. The impact of aging on oxygen storage capacity (OSC) of the converters was studied by propene pulse experiments. A trend of decreased pulse conversion was noted above 120 000 km. OSC and NO-conversion showed considerable difference between individuals with similar mileage. A number of high-mileage units perform well while a few low-mileage converters appear to be next to destroyed. The surface characterization shows that the main cause of deactivation was loss of specific surface, both of washcoat and precious metals. This is most likely due to exposure to high temperatures. Poisoning elements, typically phosphorus, lead, sulphur and calcium, are found on the catalysts surface.
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| 45. |
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