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- Rissler, Jenny, et al.
(författare)
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A set-up for respiratory tract deposition efficiency measurements (15–5000 nm) and first results for a group of children and adults
- 2017
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Ingår i: Aerosol and Air Quality Research. - : AAGR Aerosol and Air Quality Research. - 1680-8584 .- 2071-1409. ; 17:6, s. 1244-1255
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Tidskriftsartikel (refereegranskat)abstract
- Exposure to airborne particulate matter is associated with a number of negative health effects ranging from respiratorydiseases to systemic effects and cancer. One important factor for understanding the health effects is the individual variationin the respiratory tract deposition of inhaled particles. In this study, we describe an experimental set-up for size-resolvedmeasurements of the lung deposited fraction of airborne particles, covering the diameter range from 15 to 5000 nm. Theset-up includes a system for generating a stable aerosol with a sufficiently broad size distribution. We used a scanningmobility particle sizer and an aerodynamic particle sizer to determine particle number and size. The set-up was used toinvestigate individual differences in the deposition fraction (DF) of particles in the respiratory tract for a group of 67subjects of both sexes aged 7–70 years. The measured DF was applied to two model aerosols, one representing an urbanenvironment and one a rural environment, and the particle deposition rates were derived (i.e., the deposited amount ofparticles per unit time). Furthermore, the deposition rates were normalized to lung surface area and body mass – two dosemeasures that are considered relevant for the health effects of airborne particles. In addition to validation of the set-up, weshow that there is a large individual variation in DF, with some subjects having a DF that is more than twice as high as thatof others. Although we observe differences in the DF between different subgroups, most individual variation wasexplained neither by age nor by gender. When normalizing the deposition rates to lung surface area or body mass, thedeposition rates of children become significantly higher than those of adults. Furthermore, the individual variability islarger for the lung surface area or body mass normalized deposition rates than for DF
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- Rissler, Jenny, et al.
(författare)
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Deposition efficiency of inhaled particles (15-5000 nm) related to breathing pattern and lung function : An experimental study in healthy children and adults
- 2017
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Ingår i: Particle and Fibre Toxicology. - : Springer Science and Business Media LLC. - 1743-8977. ; 14:1
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Tidskriftsartikel (refereegranskat)abstract
- Background: Exposure to airborne particles has a major impact on global health. The probability of these particles to deposit in the respiratory tract during breathing is essential for their toxic effects. Observations have shown that there is a substantial variability in deposition between subjects, not only due to respiratory diseases, but also among individuals with healthy lungs. The factors determining this variability are, however, not fully understood. Method: In this study we experimentally investigate factors that determine individual differences in the respiratory tract depositions of inhaled particles for healthy subjects at relaxed breathing. The study covers particles of diameters 15-5000 nm and includes 67 subjects aged 7-70 years. A comprehensive examination of lung function was performed for all subjects. Principal component analyses and multiple regression analyses were used to explore the relationships between subject characteristics and particle deposition. Results: A large individual variability in respiratory tract deposition efficiency was found. Individuals with high deposition of a certain particle size generally had high deposition for all particles <3500 nm. The individual variability was explained by two factors: breathing pattern, and lung structural and functional properties. The most important predictors were found to be breathing frequency and anatomical airway dead space. We also present a linear regression model describing the deposition based on four variables: tidal volume, breathing frequency, anatomical dead space and resistance of the respiratory system (the latter measured with impulse oscillometry). Conclusions: To understand why some individuals are more susceptible to airborne particles we must understand, and take into account, the individual variability in the probability of particles to deposit in the respiratory tract by considering not only breathing patterns but also adequate measures of relevant structural and functional properties.
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| 58. |
- Rissler, Jenny, et al.
(författare)
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Experimental determination of deposition of diesel exhaust particles in the human respiratory tract
- 2012
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Ingår i: Journal of Aerosol Science. - : Elsevier BV. - 0021-8502 .- 1879-1964. ; 48, s. 18-33
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Tidskriftsartikel (refereegranskat)abstract
- Diesel emissions are a major contributor to combustion-generated airborne ambient particles. To understand the role of diesel particulate emissions on health effects, it is important to predict the actual particulate dose deposited in the human respiratory tract, with respect to number, surface area and mass. This is complicated by the agglomerate nature of some of these particles. In this study the respiratory tract deposition fraction in the size range 10-500 nm, was determined for 10 healthy volunteers during both idling and transient engine running conditions of a heavy duty diesel engine. The aerosol was characterized with respect to both chemical and physical properties including size resolved particle effective density. The dominating part of the emitted particles had an agglomerate structure. For those formed during transient running conditions, the relationship between particle mass and mobility diameter could be described by a power law function. This was not the case during idling, most likely because of volatile compounds condensing on the agglomerates. The respiratory tract particle deposition revealed large intra-subject variability with some subjects receiving a dose that was twice as high as that of others, when exposed to the same particle concentration. Associations were found between total deposited fractions (TDF), and breathing pattern. There was a difference between the idling and transient cycle with TDF being higher with respect to number during idling. The measured size-dependent deposition fraction of the agglomerated exhaust particles from both running conditions was nearly identical and closely resembled that of spherical hydrophobic particles, if plotted as a function of mobility diameter. Thus, for the size range covered, the mobility diameter could well describe the diameter-dependent particle respiratory tract deposition probability, regardless of the agglomeration state of the particles. Whilst mobility diameter well describes the deposition fraction, more information about particle characteristics is needed to convert this to volume equivalent diameter or estimate dose with respect to surface area or mass. A methodology is presented and applied to calculate deposited dose by surface area and mass of agglomerated particles. The methodology may be useful in similar studies estimating dose to the lung, deposition onto cell cultures and in animal studies. (C) 2012 Elsevier Ltd. All rights reserved.
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