Key Factors Controlling Number Concentrations of Non-charged Particles: An Experimental Study
Abstract The charging state of submicron particles strongly affects the number of particles deposited on the inner surface of human airways during inhalation, and an increase in this number leads to adverse effects on human health. However, the key factors controlling the charging state of particles...
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| Format: | Article |
| Language: | English |
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Springer
2024-02-01
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| Series: | Aerosol and Air Quality Research |
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| Online Access: | https://doi.org/10.4209/aaqr.220382 |
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| author | Tatsuhiro Mori Ayumi Iwata Ryoya Tabata Tomoaki Okuda |
| author_facet | Tatsuhiro Mori Ayumi Iwata Ryoya Tabata Tomoaki Okuda |
| author_sort | Tatsuhiro Mori |
| collection | DOAJ |
| description | Abstract The charging state of submicron particles strongly affects the number of particles deposited on the inner surface of human airways during inhalation, and an increase in this number leads to adverse effects on human health. However, the key factors controlling the charging state of particles are poorly understood because of the limited measurements of the number concentrations of charged submicron particles. In order to experimentally investigate the key factors controlling the number concentration of charged particles, the technique for accurately measuring the number concentration of non-charged particles (Nnon-charge) was improved based on a system consisting of optical particle counters and a parallel-plate particle separator to which a high voltage (1.0–1.5 kV) was applied. The ratio of the Nnon-charge to the total number concentration of particles (Ntotal), with diameters 0.3–0.5 µm, was used as a metric of the number fraction of non-charged particles. A decrease in the Nnon-charge/Ntotal ratio with an increase in the negative ion concentration (nion–) and the nion–/Ntotal ratio under stable meteorological conditions showed an increase in the number of charged particles by collisions between aerosols and ions. Under fluctuating humidity conditions, the Nnon-charge/Ntotal ratio also decreased with an increase in the nion– and the nion–/Ntotal ratio. Particularly, the decrease rate in the Nnon-charge/Ntotal ratio was greater at higher nion– and nion–/Ntotal ratio values than that under stable meteorological conditions. This suggests that the generation of water vapor drives an increase in ion concentration, leading to frequent collisions between excessive negative ions and aerosols. A quantitative understanding of the changes in the number fraction of charged particles with increasing humidity and nion– can assist in estimating the number of particles deposited on the inner surface of human airways. |
| format | Article |
| id | doaj-art-0d9c1b6553544dd48fbd8972eeeec377 |
| institution | Kabale University |
| issn | 1680-8584 2071-1409 |
| language | English |
| publishDate | 2024-02-01 |
| publisher | Springer |
| record_format | Article |
| series | Aerosol and Air Quality Research |
| spelling | doaj-art-0d9c1b6553544dd48fbd8972eeeec3772025-02-09T12:23:39ZengSpringerAerosol and Air Quality Research1680-85842071-14092024-02-0124411410.4209/aaqr.220382Key Factors Controlling Number Concentrations of Non-charged Particles: An Experimental StudyTatsuhiro Mori0Ayumi Iwata1Ryoya Tabata2Tomoaki Okuda3Department of Applied Chemistry, Faculty of Science and Technology, Keio UniversityDepartment of Applied Chemistry, Faculty of Science and Technology, Keio UniversityDepartment of Applied Chemistry, Faculty of Science and Technology, Keio UniversityDepartment of Applied Chemistry, Faculty of Science and Technology, Keio UniversityAbstract The charging state of submicron particles strongly affects the number of particles deposited on the inner surface of human airways during inhalation, and an increase in this number leads to adverse effects on human health. However, the key factors controlling the charging state of particles are poorly understood because of the limited measurements of the number concentrations of charged submicron particles. In order to experimentally investigate the key factors controlling the number concentration of charged particles, the technique for accurately measuring the number concentration of non-charged particles (Nnon-charge) was improved based on a system consisting of optical particle counters and a parallel-plate particle separator to which a high voltage (1.0–1.5 kV) was applied. The ratio of the Nnon-charge to the total number concentration of particles (Ntotal), with diameters 0.3–0.5 µm, was used as a metric of the number fraction of non-charged particles. A decrease in the Nnon-charge/Ntotal ratio with an increase in the negative ion concentration (nion–) and the nion–/Ntotal ratio under stable meteorological conditions showed an increase in the number of charged particles by collisions between aerosols and ions. Under fluctuating humidity conditions, the Nnon-charge/Ntotal ratio also decreased with an increase in the nion– and the nion–/Ntotal ratio. Particularly, the decrease rate in the Nnon-charge/Ntotal ratio was greater at higher nion– and nion–/Ntotal ratio values than that under stable meteorological conditions. This suggests that the generation of water vapor drives an increase in ion concentration, leading to frequent collisions between excessive negative ions and aerosols. A quantitative understanding of the changes in the number fraction of charged particles with increasing humidity and nion– can assist in estimating the number of particles deposited on the inner surface of human airways.https://doi.org/10.4209/aaqr.220382Number fraction of non-charged particleVolumetric humidityExperimentsOptical particle countersParallel-plate particle separator |
| spellingShingle | Tatsuhiro Mori Ayumi Iwata Ryoya Tabata Tomoaki Okuda Key Factors Controlling Number Concentrations of Non-charged Particles: An Experimental Study Aerosol and Air Quality Research Number fraction of non-charged particle Volumetric humidity Experiments Optical particle counters Parallel-plate particle separator |
| title | Key Factors Controlling Number Concentrations of Non-charged Particles: An Experimental Study |
| title_full | Key Factors Controlling Number Concentrations of Non-charged Particles: An Experimental Study |
| title_fullStr | Key Factors Controlling Number Concentrations of Non-charged Particles: An Experimental Study |
| title_full_unstemmed | Key Factors Controlling Number Concentrations of Non-charged Particles: An Experimental Study |
| title_short | Key Factors Controlling Number Concentrations of Non-charged Particles: An Experimental Study |
| title_sort | key factors controlling number concentrations of non charged particles an experimental study |
| topic | Number fraction of non-charged particle Volumetric humidity Experiments Optical particle counters Parallel-plate particle separator |
| url | https://doi.org/10.4209/aaqr.220382 |
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