T. WU, Investigation of saliva and saline droplet size measurement for COVID-19 infection control, invited talk at APMP Webinar on APMP’s Responses to COVID-19, Nov 2022
Abstract:
COVID-19 virus has been reported to be spread in part by infectious droplets and aerosols produced when infected individuals speak or cough. The size of the droplet will decide the transport distance in air, its life span, risk of virus infection, safety distance, etc. Several published papers have shown conflicting results in measured size distribution of such droplets. Thus, it is important to investigate the droplet size measurement accuracy for more effective infection control. We have conducted this project in response to the COVID-19 and future pandemics. This project is overseed by NMC, A*STAR, with five participating APMP member institutes (NMC, CMS/ITRI, NIM, KRISS, HSA). We also developed droplet size measurement methodology, circulated the droplet-generator with test chamber among 4 labs, made droplet size measurement by commercial instruments and evaluated their deviations. We have developed a test chamber for droplet size measurement. 18.1% and 6.5% (w/w) saline and artificial saliva were used to produce droplets via an ULV fogger. We have analysed the composition of artificial saliva with good accuracy. The droplet volume equivalent diameter (VED) measurements have been made by commercial particle sizers: aerodynamic particle sizer (APS) or aerosol spectrometer (AS) in 4 metrology labs (NMC, CMS, NIM, KRISS). This project has investigated saline and artificial saliva droplet size measurement (by AS and APS) with well-designed experiment, for the first time among all national metrology institutes. We have found that new reference size standard for artificial saliva and saline droplet size measurement is needed, due to material density effect on APS sizing. More research work is needed to develop a droplet size reference standard to establish traceability for saliva and saline droplet size measurement, and to calibrate commercial instruments.
License type:
Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0)
Funding Info:
This research / project is supported by the APMP - APMP’s Response Programme against COVID-19
Grant Reference no. : APMP’s Response Programme against COVID-19 under Project: COVID-2020-01