Skip to main content
Dryad logo

Hygroscopic growth and size distribution data for: In situ measurements of human cough aerosol hygroscopicity

Citation

Groth, Robert et al. (2021), Hygroscopic growth and size distribution data for: In situ measurements of human cough aerosol hygroscopicity, Dryad, Dataset, https://doi.org/10.5061/dryad.fn2z34tt8

Abstract

The airborne dynamics of respiratory droplets, and the transmission routes of pathogens embedded within them, are governed primarily by the diameter of the particles. These particles are composed of the fluid which lines the respiratory tract, and is primarily mucins and salts, which will interact with the atmosphere and evaporate to reach an equilibrium diameter. Measuring organic volume fraction (OVF) of cough aerosol has proved challenging due to large variability and low material volume produced after coughing. Here, the diametric hygroscopic growth factors (GF) of the cough aerosol produced by healthy participants were measured in situ using a rotating aerosol suspension chamber and a humidification tandem differential mobility analyser. Using hygroscopicity models, it was estimated that the average OVF in the evaporated cough aerosol was 0.88±0.07 and the average GF at 90% relative humidity (RH) was 1.31±0.03. To reach equilibrium in dry air the droplets will reduce in diameter by a factor of approximately 2.8 with an evaporation factor of 0.36±0.05. Hysteresis was observed in cough aerosol at RH = ~35% and RH = ~65% for efflorescence and deliquescence, respectively, and may depend on the OVF. The same behaviour and GF was observed in nebulised bovine bronchoalveolar lavage fluid.

Methods

The data was collected by having human participants voluntarily cough into a sealed and particle-free rotating drum. The cough aerosol hygroscopic growth was then measured using a humidity ramp in a humidification tandem differential mobility analyser (H-TDMA) in both hydration and dehydration modes. The size distributions of the participant's cough aerosol was also measured using a scanning mobility particle sizer (SMPS).

The data was preprocessed to be used with the TDMAinv algorithm, and the hygroscopic growth data presented in the manuscript is presented here (.mat) and are the resulting data extracted from the Igor experiments. Additionally, the SMPS data (size distribution) for all participants is presented here (.txt) as exported data from Aerosol Instrument Manager (AIM).

Usage Notes

The data reported in the manuscript consist of the following tables in the .mat files: data_LR_deli, data_HR_deli, data_LR_effl, data_HR_effl. The data here (.mat) are compatible with MATLAB, and the variables of interest are RetrGFvolAVG (hygroscopic growth factor) and RHdma2Avg (RH at which the GF is measured).

The readme file (Groth_2021_hygro_readme.txt) contains more information relating to usage of the data.

Funding

Australian Research Council, Award: DP170102733