Preprints
https://doi.org/10.5194/egusphere-2022-256
https://doi.org/10.5194/egusphere-2022-256
 
03 May 2022
03 May 2022
Status: this preprint is open for discussion.

Impact of water uptake and mixing state on submicron particles deposition in the human respiratory tract (HRT): Based on explicit hygroscopicity measurements at HRT-like conditions

Ruiqi Man1, Zhijun Wu1,2, Taomou Zong1, Aristeidis Voliotis3,4, Johannes Größ5, Dominik van Pinxteren5, Limin Zeng1, Hartmut Herrmann5, Alfred Wiedensohler5, and Min Hu1 Ruiqi Man et al.
  • 1State Key Joint Laboratory of Environmental Simulation and Pollution Control, College of Environmental Sciences and Engineering, Peking University, 100871, Beijing, China
  • 2Collaborative Innovation Center of Atmospheric Environment and Equipment Technology, Nanjing University of Information Science and Technology, 210044, Nanjing, China
  • 3National Centre for Atmospheric Science, Department of Earth and Environmental Science, School of Natural Sciences, The University of Manchester, Oxford Road, M13 9PL, Manchester, UK
  • 4Centre for Atmospheric Science, Department of Earth and Environmental Science, School of Natural Sciences, The University of Manchester, Oxford Road, M13 9PL, Manchester, UK
  • 5Leibniz Institute for Tropospheric Research, 04318, Leipzig, Germany

Abstract. The particle hygroscopicity plays a key role in determining the particle deposition in the human respiratory tract (HRT). In this study, the effects of hygroscopicity and mixing state on regional and total deposition doses for children, adults, and elderly were quantified using the Multiple-Path Particle Dosimetry model based on the size-resolved particle hygroscopicity measurements at HRT-like conditions (relative humidity = 98 %) performed in the North China Plain. The measured particle population with an external mixing state was dominated by hygroscopic particles (number fraction = (91.5 ± 5.7) %, mean ± standard deviation (SD), the same below). Particle hygroscopic growth in the HRT led to a reduction by around 24 % in the total doses of submicron particles for all age groups. Such reduction was mainly caused by the growth of hygroscopic particles and was more pronounced in the pulmonary and tracheobronchial regions. Regardless of hygroscopicity, the elderly group had the highest total dose among the three age groups. With 270 nm in diameter as the boundary, the total deposition doses of particles smaller than this diameter were overestimated and those of larger particles were underestimated assuming no particle hygroscopic growth in the HRT. From the perspective of the daily variation, the deposition rates of hygroscopic particles with an average of 2.88 × 109 #/h (SD = 8.10 × 108 #/h) during the daytime were larger than those ((2.32 × 109) ± (2.41 × 108) #/h) at night. On the contrary, hydrophobic particles interpreted as freshly emitted soot and primary organic aerosols exhibited higher deposition rates at nighttime ((3.39 ± 1.34) × 108 #/h) than those in the day ((2.58 × 108) ± (7.60 × 107) #/h). The traffic emissions during the rush hours enhanced the deposition rate of hydrophobic particles. This work provides a more explicit assessment of the impact of hygroscopicity and mixing state on the deposition pattern of submicron particles in the HRT.

Ruiqi Man et al.

Status: open (until 14 Jun 2022)

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Ruiqi Man et al.

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Short summary
Regional and total deposition doses for different age groups were quantified based on explicit hygroscopicity measurements. This work found that particle hygroscopic growth led to a reduction (~24 %) in the total dose. The deposition rate of hygroscopic particles was higher in the daytime, while hydrophobic particles exhibited higher rate at nighttime and rush hours. The results will deepen the understanding of the impact of hygroscopicity and mixing state on deposition pattern in lungs.