Determination of the deposition of urban submicron aerosols in the human respiratory tract considering hygroscopic growth

• Published in: Atmospheric environment (1994) Vol. 356; p. 121289
• Main Authors: Yu, Aoyuan, Lu, Jiayuan, Shen, Xiaojing, Hu, Xinyao, Zhang, Yangmei, Liu, Quan, Tong, Hongfei, Liang, Linlin, Liu, Lei, Ma, Qianli, Han, Lujie, Che, Huizheng, Zhang, Xiaoye, Sun, Junying
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.09.2025
• Subjects: China; Deposition dose; Deposition rate; diurnal variation; dosimetry; environment; Human respiratory tract; humans; Hygroscopic growth; hygroscopicity; particle size; pollution; respiratory system; surface area; China; Deposition rate; Human respiratory tract; Deposition dose; Hygroscopic growth
• ISSN: 1352-2310
• DOI: 10.1016/j.atmosenv.2025.121289

Assessing particle exposure in the human respiratory tract (HRT) is critical for understanding its health risks. Hygroscopicity is a key characteristic that influences particle deposition by changing particle size in the human respiratory tract. In this study, the daily deposited particle doses and rates of submicron particles in different regions of the HRT, as well as the total HRT considering hygroscopic growth, were comprehensively evaluated using the Multiple-Path Particle Dosimetry model (MPPD) and size-resolved particle hygroscopicity measurements obtained with the Volatility Hygroscopicity Tandem Differential Mobility Analyzer (VH–TDMA) in urban Beijing. Taking particle hygroscopicity into account, the deposition fractions (DFs) of particles smaller than 300 nm were 25.4 % lower than those of dry particles, while the DFs of particles larger than 300 nm increased by 23.0 %. The results indicated that the daily deposited particle number dose (DPNd), mass dose (DPMd) and surface area dose (DPSd) were predominantly deposited in the pulmonary (P) region, accounting for 53 %, 47 %, and 54 % of total respiratory tract deposition, respectively. Ultrafine particles (UFPs; <100 nm) dominated the daily DPNd, accounting for 86.4 %, 94.4 %, and 76.8 % of the total DPNd during the whole sampling period, new particle formation (NPF) days, and pollution period, respectively. In contrast, accumulation mode particles were the primary contributors to both DPMd and DPSd. From the perspective of diurnal variation, the highest deposited particle number rate (DPNr) in the HRT occurred during the daytime and evening rush hours, with peak values observed at 10:00 and 18:00, reaching 3.5 × 109 and 4.5 × 109 particles h−1, respectively. The peak times for the deposited particle mass rate (DPMr) and surface area rate (DPSr) varied across different periods. •Comprehensive assessment of the deposition of submicron aerosol particles in the human respiratory tract was addressed.•The effect of particle hygroscopicity on its deposition in the human respiratory tract was considered.•Submicron aerosol particles were predominantly deposited in the pulmonary region.•Daily DPNd was primarily attributed to ultrafine particles, while DPMd and DPSd were dominated by accumulation mode particles.