Keita Kurai, Hikaru Miyamoto, Nobuyuki Takegawa  This email address is being protected from spambots. You need JavaScript enabled to view it. 

Department of Chemistry, Graduate School of Science, Tokyo Metropolitan University, Hachioji, Tokyo 192-0397, Japan

Received: January 25, 2024
Revised: April 20, 2024
Accepted: April 28, 2024

 Copyright The Author(s). This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are cited.

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Kurai, K., Miyamoto, H., Takegawa, N. (2024). Evaporation of Water from Airborne Droplets Containing Sodium Chloride, Mucin, and Surfactant. Aerosol Air Qual. Res.


  • The evaporation of water from airborne model respiratory droplets was investigated.
  • The size of particles containing mucin and surfactant showed weak RH dependency.
  • Mucin and surfactant had a significant effect on the water evaporation from droplets.


We conducted laboratory experiments to investigate the evaporation of water from airborne model respiratory droplets containing sodium chloride (NaCl) as an inorganic salt, mucin as a glycoprotein, and dipalmitoyl phosphatidylcholine (DPPC) as a surfactant. The model respiratory droplets were introduced into a flow tube, in which the relative humidity (RH) was controlled at 30%, 50%, and 70%. The residence time of the model droplets under the RH-controlled conditions was altered by varying the length of the flow tube. Size-segregated particle number concentrations were measured using an optical particle counter placed at the end of the flow tube vented to the atmosphere. The particle number size distributions for NaCl exhibited systematic changes with an increasing RH. The particle number size distributions for (NaCl + mucin) and (NaCl + mucin + DPPC) exhibited very weak RH dependency. These results suggest that the presence of mucin and DPPC had a significant effect on the RH dependency of the evaporation of water from the model droplets.

Keywords: Respiratory droplets, Relative humidity, Glycoprotein, Surfactant

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