(285a) Development of Enclosed Space Membrane Air Filtration for Viral Aerosol Capture and Deactivation

The occurrence of the COVID-19 pandemic presented a global challenge to human health. The highly contagious disease caused by the SARS-CoV-2 virus spread rapidly around the world in part due to its ability to spread via respiratory aerosols, even from asymptomatic infected individuals. A number of studies have demonstrated efficient spread of COVID-19 via viral aerosols (<5um particles),^1,2 which can persist as aerosols in enclosed spaces like hospital rooms or restaurants indefinitely.³ To address the respiratory spread of SARS-CoV-2 and other respiratory illnesses, in this work we develop hollow fiber membrane modules for application to enclosed space air filtration.

For enclosed space air filtration of viral aerosols, a large volume of air must be passed through a filter capable of separating small aerosols from air with low applied pressures for real world application. Therefore, we chose to employ polymeric microfiltration hollow fiber membranes (HFMs) as an ideal configuration for enclosed space air filtration. HFMs are polymeric materials created with cylindrical structure, in which separation occurs across the membrane in the radial direction. This geometry allows combination of many hollow fibers in parallel within an outer shell to yield a very high active separation area per unit volume, which is ideal for the large volume filtration needs of enclosed space air filtration. Polymeric microfiltration membrane materials are advantageous for aerosol separations due to their thin structures requiring low pressure drop for moderately high transport and due to their defined pore structure, which allows efficient removal of airborne particles of defined sizes.

Investigations of hollow fiber modules in aerosol separations have begun to increase in recent years. HFMs have shown promise for removing PM2.5 fine particulate matter from air, using hydrophobic membrane materials which allow for potential cleaning and reuse.⁴ Similar designs have also been successfully used to filter PM0.1 ultrafine particulate matter from air, showing the potential for size-selective separations by tuning membrane properties.⁵ Recent work also investigated the role of membrane hydrophilicity and humidity on the effect of filtration efficiency, which provides some guidance for developing the next generation of HFMs for efficient separation of various aerosols.⁶

In this work, we characterize microfiltration type hollow fiber microfiltration membrane modules for their air transport properties and ability to reject aerosol particles of various sizes and types. We investigate change in transport and rejection over time as a function of particle size and type using particles made from polystyrene latex, bovine serum albumin, and liposomes labeled with SARS-CoV-2 spike glycoprotein (SGP). Furthermore, we characterize the ability of HFM modules to eliminate infectivity of air containing SGP-pseudotyped-VSV (vesicular stomatitis virus) pseudoviral particles via a GFP reporter infection assay. We demonstrate the potential value of hollow fiber membrane modules as enclosed air space filters capable of preventing the aerosol spread of COVID-19 and other airborne respiratory illnesses as a defense against future pandemics. This project is funded by NIH-NIEHS-SRP.

1. Tang, Song, et al. "Aerosol transmission of SARS-CoV-2? Evidence, prevention and control." Environment international144 (2020): 106039.
2. Fennelly, Kevin P. "Particle sizes of infectious aerosols: implications for infection control." The Lancet Respiratory Medicine(2020).
3. Wells, William Firth. "Airborne Contagion and Air Hygiene. An Ecological Study of Droplet Infections." Airborne Contagion and Air Hygiene. An Ecological Study of Droplet Infections.(1955).
4. Xu, Huan, et al. "Preparation and properties of PTFE hollow fiber membranes for the removal of ultrafine particles in PM 2.5 with repetitive usage capability." RSC advances67 (2018): 38245-38258.
5. Bulejko, Pavel, et al. "Air filtration performance of symmetric polypropylene hollow-fibre membranes for nanoparticle removal." Separation and Purification Technology197 (2018): 122-128.
6. Wang, Liang-Yi, E. Yu Liya, and Tai-Shung Chung. "Effects of relative humidity, particle hygroscopicity, and filter hydrophilicity on filtration performance of hollow fiber air filters." Journal of Membrane Science595 (2020): 117561.