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- Isaxon, Christina, et al.
(författare)
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Contribution of indoor-generated particles to residential exposure
- 2015
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Ingår i: Atmospheric Environment. - : Elsevier BV. - 1352-2310 .- 1873-2844. ; 106, s. 458-466
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Tidskriftsartikel (refereegranskat)abstract
- The majority of airborne particles in residences, when expressed as number concentrations, are generated by the residents themselves, through combustion/thermal related activities. These particles have a considerably smaller diameter than 2.5 mu m and, due to the combination of their small size, chemical composition (e.g. soot) and intermittently very high concentrations, should be regarded as having potential to cause adverse health effects. In this study, time resolved airborne particle measurements were conducted for seven consecutive days in 22 randomly selected homes in the urban area of Lund in southern Sweden. The main purpose of the study was to analyze the influence of human activities on the concentration of particles in indoor air. Focus was on number concentrations of particles with diameters <300 nm generated by indoor activities, and how these contribute to the integrated daily residential exposure. Correlations between these particles and soot mass concentration in total dust were also investigated. It was found that candle burning and activities related to cooking (using a frying pan, oven, toaster, and their combinations) were the major particle sources. The frequency of occurrence of a given concentration indoors and outdoors was compared for ultrafine particles. Indoor data was sorted into non-occupancy and occupancy time, and the occupancy time was further divided into non-activity and activity influenced time. It was found that high levels (above 10(4) cm(-3)) indoors mainly occur during active periods of occupancy, while the concentration during non-activity influenced time differs very little from non-occupancy time. Total integrated daily residential exposure of ultrafine particles was calculated for 22 homes, the contribution from known activities was 66%, from unknown activities 20%, and from background/non-activity 14%. The collected data also allowed for estimates of particle source strengths for specific activities, and for some activities it was possible to estimate correlations between the number concentration of ultrafine particles and the mass concentration of soot in total dust in 10 homes. Particle source strengths (for 7 specific activities) ranged from 1.6.10(12) to 4.5.10(12) min(-1). The correlation between ultrafine particles and mass concentration of soot in total dust varied between 0.37 and 0.85, with an average of 0.56 (Pearson correlation coefficient). This study clearly shows that due to the importance of indoor sources, residential exposure to ultrafine particles cannot be characterized by ambient measurements alone. (C) 2014 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/3.0/).
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| 2. |
- Rissler, Jenny, et al.
(författare)
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Effective Density and Mixing State of Aerosol Particles in a Near-Traffic Urban Environment.
- 2014
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Ingår i: Environmental Science & Technology. - : American Chemical Society (ACS). - 1520-5851 .- 0013-936X. ; 48:11, s. 6300-6308
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Tidskriftsartikel (refereegranskat)abstract
- In urban environments, airborne particles are continuously emitted, followed by atmospheric aging. Also, particles emitted elsewhere, transported by winds, contribute to the urban aerosol. We studied the effective density (mass-mobility relationship) and mixing state with respect to the density of particles in central Copenhagen, in wintertime. The results are related to particle origin, morphology, and aging. Using a differential mobility analyzer-aerosol particle mass analyzer (DMA-APM), we determined that particles in the diameter range of 50-400 nm were of two groups: porous soot aggregates and more dense particles. Both groups were present at each size in varying proportions. Two types of temporal variability in the relative number fraction of the two groups were found: soot correlated with intense traffic in a diel pattern and dense particles increased during episodes with long-range transport from polluted continental areas. The effective density of each group was relatively stable over time, especially of the soot aggregates, which had effective densities similar to those observed in laboratory studies of fresh diesel exhaust emissions. When heated to 300 °C, the soot aggregate volatile mass fraction was ∼10%. For the dense particles, the volatile mass fraction varied from ∼80% to nearly 100%.
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| 5. |
- Omelekhina, Yuliya, et al.
(författare)
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Chemical composition of airborne particles inside and outside a Swedish residence assessed by real time aerosol mass spectrometry
- 2018
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- A number of deleterious health effects have been identified from exposure to outdoor air-borne particulate matter. This issue is complicated by the fact that people are spending most of the time indoors, where particles of both indoor and outdoor origin are present. The aim of this work was to assess the differences in particle chemical composition inside and outside of the residence and gain better understanding about major contributors to the observed levels indoors. Our results showed that indoor aerosol mass concentration exceeded the outdoor values mainly due to the contribution of organic matter from indoor sources during the presence of the residents at home. The infiltration of chemical species from outdoors was not the major factor determining indoor aerosol mass concentration and chemical composition.1 INTRODUCTIONConsidering that on average in developed countries we spend about 65% (Brashe and Bis-chof) of our time in private homes, the understanding of exposure to particulate matter in homes is important, yet knowledge is sparse. Indoors, aerosol concentrations come from in-door sources, infiltrate from outdoors and can be formed through reactions of gas-phase precursors emitted both indoors and outdoors. Several characteristics and processes influence the properties of aerosols indoors, among them: active indoor sources (presence of occupants), outdoor aerosol characteristics, physicochemical particle transformations during infiltration and while indoors, ventilation type, tightness of the building envelope and particle deposition (Morawska et al., 2013). In this study, we aimed to investigate the differences in chemical composition between aerosols inside and outside of the residence and to identify the origin of major contributors to the particle levels indoors. We report preliminary results of measure-ments for a 1-month period in an occupied apartment. 2 METHODS Indoor and outdoor measurements were performed in an occupied residence in Malmö, Swe-den. It was a naturally ventilated four-room apartment (292 m3), located in a three-store con-crete building surrounded by a green zone. A Time-of-Flight Aerosol Mass Spectrometer (AMS, DeCarlo et al., 2006) was used to measure particle mass loadings and size-resolved mass distributions (size range of 50-500 nm) of indoor and outdoor organic, sulphate, nitrate, ammonium and chloride aerosols. An automatic switching valve alternated between indoor and outdoor lines with a time interval of 20 and 10 minutes in indoor and outdoor air, respectively. Both sampling lines were mounted at the ground floor level and led to the basement where the aerosol was dried and measured by AMS. Calculated residence time of the particles in line was 1.5 minutes. Indoor sampling line was heated and insulated, additional carrier flow was used to lower the resi-dence time. Indoor to outdoor (I/O) ratios were calculated and used for comparisons of differences in aerosol composition inside and outside of the residence.3 RESULTS AND DISCUSSIONThe results showed higher total average mass concentration indoors (12.9 μg/m3) compared to outdoors (5.4 μg/m3) during entire measuring period. Indoor to outdoor (I/O) ratio for or-ganics was 6.7, for nitrate 0.3, for sulphate 0.5, for ammonium 0.2 and for chloride 0.2. Or-ganic matter was the dominant species indoors, accounting for most of the total mass (92 %) due to contribution from indoor sources during the time when residents were at home, i.e. occupancy period. Figure 1A illustrates elevated particle mass concentrations when different indoor activities took place. Effects of penetration and phase change of the outdoor particle species can be observed during non-occupancy period (Figure 1B). Non-occupancy time ac-counted only to 7 % of the total monitoring period and did not have much influence on parti-cle mass concentration indoors.Ammonium nitrate (NH4NO3) and ammonium chlorine (NH4Cl) are semi-volatile aerosol species, thus, gas-to-particle partitioning depends on temperature, relative humidity, particle size and gas phase concentrations of ammonia, nitric acid and chlorine as outdoor air is transported indoors (Mozurkewich, 1993; Lunden et al., 2004). Such phase transitions are especially pronounced in the cold period of the year. The outdoor weather conditions varied during this time with Tout from -8.8 to 9.7 °C and RHout from 58 to 100 %. Indoors, Tin ranged from 20 to 26.1 °C and RHin from 27 to 50 %. Low value of I/O ratio for non-volatile sul-phate can be explained by dominating of the outdoor sources and reflects reduced infiltra-tion. The outdoor total mass concentration in urban sites measured by TOF-AMS was comparable with previous studies (Crippa et al., 2014; Jimenez et al., 2009). Some local sources, such as emissions from fireplaces by neighbours and from adjacent fast food restaurants could have contributed to the outdoor loadings. 4 CONCLUSIONSIn general, the differences in chemical composition of particles found indoors and outdoors becomes apparent from the results. Levels of organics in indoor environments were mainly influenced by indoor sources, thus, these should not be neglected when considering possible health effects. Additionally, reduced air exchange rate in the apartment in Scandinavia during wintertime enhanced aerosol accumulation and physicochemical transformation indoors.ACKNOWLEDGEMENTThis work was financed by the Swedish Research Council FORMAS (Project Dnr 942-2015-1029).
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| 6. |
- Hagerman, Inger, et al.
(författare)
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Effects on heart rate variability by artificially generated indoor nano-sized particles in a chamber study
- 2014
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Ingår i: Atmospheric Environment. - : Elsevier BV. - 1352-2310. ; 88, s. 165-171
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Tidskriftsartikel (refereegranskat)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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| 8. |
- Isaxon, Christina, et al.
(författare)
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A Novel System for Source Characterization and Controlled Human Exposure to Nanoparticle Aggregates Generated During Gas–Metal Arc Welding
- 2013
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Ingår i: Aerosol Science and Technology. - : Informa UK Limited. - 1521-7388 .- 0278-6826. ; 47:1, s. 52-59
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Tidskriftsartikel (refereegranskat)abstract
- Abstract in Undetermined The aim of this study was to achieve a method to perform detailed characterization and human exposure studies of nanosized and nanostructured aerosol particles. The source chosen was mild steel, active gas, arc welding fume. The setup consisted of a generation chamber, where welding can be performed, connected to an airtight stainless steel 22 m(3) exposure chamber. Instrumentation, consisting of a tapered element oscillating microbalance, a scanning mobility particle sizer, and a sampler for electron microscopy and particle-induced X-ray emission analysis was connected to the stainless steel chamber. The feasibility of the system for human exposure studies was evaluated by exposing 31 human volunteers, in groups of three, to a test aerosol containing 1 mg/m(3) welding fumes and to conditioned, filtered air. The results show that an aerosol that accurately represents dilute welding fume exposures that occur in workplaces can be produced in a controlled manner, and that the experimental setup can be used for 6 h, double-blind, exposures of human subjects. Particle mass concentration levels could be varied from <5 mu g/m(3) to more than 1000 mu g/m(3). Fumes from metal active gas welding showed a unimodal size distribution with a mean mobility diameter of 160 nm, transmission electron microscopy showed aggregates with a clearly nanosized structure.
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