| 1. |
- Eriksson, Axel Christian, et al.
(författare)
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Influence of airborne particles' chemical composition on SVOC uptake from PVC flooring - time resolved analysis with aerosol mass spectrometry
- 2020
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Ingår i: Environmental Science & Technology. - : American Chemical Society (ACS). - 1520-5851 .- 0013-936X. ; , s. 85-91
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Tidskriftsartikel (refereegranskat)abstract
- We sampled ammonium sulfate particles and indoor particles of outdoor origin through a small chamber covered with polyvinyl chloride (PVC) flooring. We measured the uptake of semi-volatile organic compounds (SVOC) by the airborne particles in real time. The particles acquired SVOC mass fractions up to 10%. The phthalate ester DEHP (di(2-ethylhexyl)phthalate), a known endocrine disruptor, contributed by approximately half of the sorbed SVOC mass. The indoor particles acquired higher DEHP fraction than laboratory generated ammonium sulfate aerosol. We attribute this increased uptake to absorption by organic matter present in the indoor particles. Using a thermodenuder to remove volatile components, predominantly organics, reduced SVOC uptake. Positive matrix factorization applied to the organic mass spectra suggests that hydrocarbon-like organic aerosol (typically fresh traffic exhaust) sorbs DEHP more efficiently than aged organic aerosol. SVOC uptake is one of the processes that modifies outdoor pollution particles after they penetrate buildings, where the majority of exposure occurs. Particles from indoor sources, typically dominated by organic matter, will undergo such processes as well. Aerosol mass spectrometry improves the time resolution of experimental investigations into these processes, and enables experiments with lower, relevant particle concentrations. Additionally, particle size resolved results are readily obtained.
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| 2. |
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| 3. |
- Eriksson, Axel C., et al.
(författare)
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The role of organic fraction of aerosol particles in uptake of indoor SVOC investigated with real time aerosol mass spectrometry
- 2018
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Ingår i: 15th Conference of the International Society of Indoor Air Quality and Climate, INDOOR AIR 2018. - 9781713826514
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Konferensbidrag (refereegranskat)abstract
- We investigate the uptake of the Di(2-ethylhexyl) phthalate (DEHP) by laboratory generated and ambient aerosol particles passing through a 1.2 liter chamber covered with vinyl flooring on its internal surfaces. We found approximately five times more efficient DEHP uptake on a mass basis by organic particles (ambient particles) compared to laboratory generated salt particles. The increased uptake is likely due to increased adsorption by pre-existing organic aerosol, which is abundant in the ambient aerosol particles. This implies that compounds with adverse health outcomes are added to particles in indoor air after infiltration into buildings via gas-to-particle conversion of indoor generated SVOCs. We show that aerosol mass spectrometry is a suitable tool for highly time-resolved investigations of this process.
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| 4. |
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| 5. |
- Zewinger, Stephen, et al.
(författare)
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Relations between lipoprotein(a) concentrations, LPA genetic variants, and the risk of mortality in patients with established coronary heart disease : a molecular and genetic association study
- 2017
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Ingår i: The Lancet Diabetes and Endocrinology. - : ELSEVIER SCIENCE INC. - 2213-8587 .- 2213-8595. ; 5:7, s. 534-543
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Tidskriftsartikel (refereegranskat)abstract
- Background: Lipoprotein(a) concentrations in plasma are associated with cardiovascular risk in the general population. Whether lipoprotein(a) concentrations or LPA genetic variants predict long-term mortality in patients with established coronary heart disease remains less clear.Methods: We obtained data from 3313 patients with established coronary heart disease in the Ludwigshafen Risk and Cardiovascular Health (LURIC) study. We tested associations of tertiles of lipoprotein(a) concentration in plasma and two LPA single-nucleotide polymorphisms ([SNPs] rs10455872 and rs3798220) with all-cause mortality and cardiovascular mortality by Cox regression analysis and with severity of disease by generalised linear modelling, with and without adjustment for age, sex, diabetes diagnosis, systolic blood pressure, BMI, smoking status, estimated glomerular filtration rate, LDL-cholesterol concentration, and use of lipid-lowering therapy. Results for plasma lipoprotein(a) concentrations were validated in five independent studies involving 10 195 patients with established coronary heart disease. Results for genetic associations were replicated through large-scale collaborative analysis in the GENIUS-CHD consortium, comprising 106 353 patients with established coronary heart disease and 19 332 deaths in 22 studies or cohorts.Findings: The median follow-up was 9.9 years. Increased severity of coronary heart disease was associated with lipoprotein(a) concentrations in plasma in the highest tertile (adjusted hazard radio [HR] 1.44, 95% CI 1.14-1.83) and the presence of either LPA SNP (1.88, 1.40-2.53). No associations were found in LURIC with all-cause mortality (highest tertile of lipoprotein(a) concentration in plasma 0.95, 0.81-1.11 and either LPA SNP 1.10, 0.92-1.31) or cardiovascular mortality (0.99, 0.81-1.2 and 1.13, 0.90-1.40, respectively) or in the validation studies.Interpretation: In patients with prevalent coronary heart disease, lipoprotein(a) concentrations and genetic variants showed no associations with mortality. We conclude that these variables are not useful risk factors to measure to predict progression to death after coronary heart disease is established.
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| 6. |
- Abera, Asmamaw, et al.
(författare)
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Air pollution measurements and land-use regression in urban sub-saharan Africa using low-cost sensors—possibilities and pitfalls
- 2020
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Ingår i: Atmosphere. - : MDPI AG. - 2073-4433. ; 11:12
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Tidskriftsartikel (refereegranskat)abstract
- Air pollution is recognized as the most important environmental factor that adversely affects human and societal wellbeing. Due to rapid urbanization, air pollution levels are increasing in the Sub-Saharan region, but there is a shortage of air pollution monitoring. Hence, exposure data to use as a base for exposure modelling and health effect assessments is also lacking. In this study, low-cost sensors were used to assess PM2.5 (particulate matter) levels in the city of Adama, Ethiopia. The measurements were conducted during two separate 1-week periods. The measurements were used to develop a land-use regression (LUR) model. The developed LUR model explained 33.4% of the variance in the concentrations of PM2.5. Two predictor variables were included in the final model, of which both were related to emissions from traffic sources. Some concern regarding influential observations remained in the final model. Long-term PM2.5 and wind direction data were obtained from the city’s meteorological station, which should be used to validate the representativeness of our sensor measurements. The PM2.5 long-term data were however not reliable. Means of obtaining good reference data combined with longer sensor measurements would be a good way forward to develop a stronger LUR model which, together with improved knowledge, can be applied towards improving the quality of health. A health impact assessment, based on the mean level of PM2.5 (23 µg/m3), presented the attributable burden of disease and showed the importance of addressing causes of these high ambient levels in the area.
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| 7. |
- Ahlberg, Erik, et al.
(författare)
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Effect of salt seed particle surface area, composition and phase on secondary organic aerosol mass yields in oxidation flow reactors
- 2019
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Ingår i: Atmospheric Chemistry and Physics. - : Copernicus GmbH. - 1680-7316 .- 1680-7324. ; 19:4, s. 2701-2712
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Tidskriftsartikel (refereegranskat)abstract
- Atmospheric particulate water is ubiquitous, affecting particle transport and uptake of gases. Yet, research on the effect of water on secondary organic aerosol (SOA) mass yields is not consistent. In this study, the SOA mass yields of an α-pinene and m-xylene mixture, at a concentration of 60 μgm-3, were examined using an oxidation flow reactor operated at a relative humidity (RH) of 60% and a residence time of 160 s. Wet or dried ammonium sulfate and ammonium nitrate seed particles were used. By varying the amount of seed particle surface area, the underestimation of SOA formation induced by the short residence time in flow reactors was confirmed. Starting at a SOA mass concentration of 5 μgm-3, the maximum yield increased by a factor of 2 with dry seed particles and on average a factor of 3.2 with wet seed particles. Hence, wet particles increased the SOA mass yield by 60% compared to the dry experiment. Maximum yield in the reactor was achieved using a surface area concentration of 1600 μm2 cm-3. This corresponded to a condensational lifetime of 20 s for low-volatility organics. The O V C ratio of SOA on wet ammonium sulfate was significantly higher than when using ammonium nitrate or dry ammonium sulfate seed particles, probably due to differences in heterogeneous chemistry.
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| 8. |
- Ahlberg, Erik, et al.
(författare)
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Measurement report : Black carbon properties and concentrations in southern Sweden urban and rural air-the importance of long-range transport
- 2023
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Ingår i: Atmospheric Chemistry and Physics. - : Copernicus GmbH. - 1680-7316 .- 1680-7324. ; 23:5, s. 3051-3064
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Tidskriftsartikel (refereegranskat)abstract
- Soot, or black carbon (BC), aerosol is a major climate forcer with severe health effects. The impacts depend strongly on particle number concentration, size and mixing state. This work reports on two field campaigns at nearby urban and rural sites, 65gkm apart, in southern Sweden during late summer 2018. BC was measured using a single-particle soot photometer (SP2) and Aethalometers (AE33). Differences in BC concentrations between the sites are driven primarily by local traffic emissions. Equivalent and refractory BC mass concentrations at the urban site were on average a factor 2.2 and 2.5, with peaks during rush hour up to a factor g1/44, higher than the rural background levels. The number fraction of particles containing a soot core was significantly higher in the city. BC particles at the urban site were on average smaller by mass and had less coating owing to fresh traffic emissions. The organic components of the fresh traffic plumes were similar in mass spectral signature to hydrocarbon-like organic aerosol (HOA), commonly associated with traffic. Despite the intense local traffic (g1/4g30g000 vehicles passing per day), PM1, including organic aerosol, was dominated by aged continental air masses even at the curbside site. The fraction of thickly coated particles at the urban site was highly correlated with the mass concentrations of all measured chemical species of PM1, consistent with aged, internally mixed aerosol. Trajectory analysis for the whole year showed that air masses arriving at the rural site from eastern Europe contained approximately double the amount of BC compared to air masses from western Europe. Furthermore, the largest regional emissions of BC transported to the rural site, from the Malmö-Copenhagen urban area, are discernible above background levels only when precipitation events are excluded. We show that continental Europe and not the Malmö-Copenhagen region is the major contributor to the background BC mass concentrations in southern Sweden.
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| 9. |
- Ahlberg, Erik, et al.
(författare)
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No particle mass enhancement from induced atmospheric ageing at a rural site in northern Europe
- 2019
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Ingår i: Atmosphere. - : MDPI AG. - 2073-4433. ; 10:7
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Tidskriftsartikel (refereegranskat)abstract
- A large portion of atmospheric aerosol particles consists of secondary material produced by oxidation reactions. The relative importance of secondary organic aerosol (SOA) can increase with improved emission regulations. A relatively simple way to study potential particle formation in the atmosphere is by using oxidation flow reactors (OFRs) which simulate atmospheric ageing. Here we report on the first ambient OFR ageing experiment in Europe, coupled with scanning mobility particle sizer (SMPS), aerosol mass spectrometer (AMS) and proton transfer reaction (PTR)-MS measurements. We found that the simulated ageing did not produce any measurable increases in particle mass or number concentrations during the two months of the campaign due to low concentrations of precursors. Losses in the reactor increased with hydroxyl radical (OH) exposure and with increasing difference between ambient and reactor temperatures, indicating fragmentation and evaporation of semivolatile material.
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| 10. |
- Ahlberg, Erik, et al.
(författare)
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Secondary organic aerosol from VOC mixtures in an oxidation flow reactor
- 2017
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Ingår i: Atmospheric Environment. - : Elsevier BV. - 1352-2310. ; 161, s. 210-220
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Tidskriftsartikel (refereegranskat)abstract
- The atmospheric organic aerosol is a tremendously complex system in terms of chemical content. Models generally treat the mixtures as ideal, something which has been questioned owing to model-measurement discrepancies. We used an oxidation flow reactor to produce secondary organic aerosol (SOA) mixtures containing oxidation products of biogenic (α-pinene, myrcene and isoprene) and anthropogenic (m-xylene) volatile organic compounds (VOCs). The resulting volume concentration and chemical composition was measured using a scanning mobility particle sizer (SMPS) and a high-resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS), respectively. The SOA mass yield of the mixtures was compared to a partitioning model constructed from single VOC experiments. The single VOC SOA mass yields with no wall-loss correction applied are comparable to previous experiments. In the mixtures containing myrcene a higher yield than expected was produced. We attribute this to an increased condensation sink, arising from myrcene producing a significantly higher number of nucleation particles compared to the other precursors. Isoprene did not produce much mass in single VOC experiments but contributed to the mass of the mixtures. The effect of high concentrations of isoprene on the OH exposure was found to be small, even at OH reactivities that previously have been reported to significantly suppress OH exposures in oxidation flow reactors. Furthermore, isoprene shifted the particle size distribution of mixtures towards larger sizes, which could be due to a change in oxidant dynamics inside the reactor.
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