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Stickiness of COVID Particles Reduces Airborne Concentration in Supermarkets

With XSEDE allocations, Comet supercomputer simulates how pathogens travel, land in the grocery store space

By Kimberly Bruch and Cynthia Dillon, SDSC Communications

Using XSEDE allocations on Comet, virus-laden particles were illustrated near shelves in a supermarket at 10 seconds after release, 100 seconds, 200 seconds and five minutes. While the amount of airborne particles decreases over time, surface-attached particles increase. Dark blue indicates particles suspended in air, orange shows particles stuck on the ceiling, light blue represents particles attached to shelves and yellow shows particles on the floor. Credit: New Jersey Institute of Technology

No one likes a sticky public surface, but when it comes to shopping for groceries during a pandemic, stickiness might not be all that bad – as long as you use hand sanitizer. With various strains of the SARS-CoV-2 virus emerging simultaneously, vaccinations are being administered and ongoing virus mitigation strategies remain on the Centers for Disease Control and Prevention's list of guidelines. In the meantime, a team of environmental engineers recently used Comet at the San Diego Supercomputer Center at the University of California San Diego to simulate how the virus' airborne pathogens travel and land in the familiar setting of the supermarket. 

Led by Professor Michel Boufadel and Research Associate Fangda Cui from the New Jersey Institute of Technology, the Comet simulations were the basis for analysis reported in an April 2021 Journal of Environmental Engineering study. The research revealed that the attachment of virus-laden particles on the shelves, floor and ceiling of the supermarket reduces the maximum concentration of suspended particles in the air by as much as 50%.

Boufadel suggested that one-way lanes in stores might be a step in the right direction, but he also said display shelves in aisles also help break the flight of virus particles

"We used allocations from the National Science Foundation's Extreme Science and Engineering Discovery Environment for these Comet simulations that helped us investigate the transport of virus-laden particles in an archetypical supermarket 40 meters long by 30 meters wide by 4.5 meters (ceiling height)," explained Boufadel. "We considered three efficiency situations of attachment on surfaces: zero percent, 25% and 100% attachment. For example, the 25% attachment efficiency means that out of 100 particles that touch the surface, only 25% attached to a surface – thus zero percent means no attachment."

Why It's Important

According to the study, the attachment of airborne, virus-laden particles on surfaces at both 25 and 100% have the same efficiency. These particles are as small as dust and don't fall onto a surface within a short time of emission, but they significantly accumulate on surfaces after five minutes or more. Boufadel suggested that one-way lanes in stores might be a step in the right direction, but he also said display shelves in aisles also help break the flight of virus particles.


How XSEDE Helped

"In this particular project, we used XSEDE as a tool to solve a simple problem (transport of particles) in a domain with a complicated geometry," said Boufadel. "The goal was a quantification, and the superior ability of XSEDE allowed us to have a high confidence in the results."

In future applications, such as examining the micron-scale (e.g., a human hair is less than 100 microns, or less than one millimeter, thick) interaction of particles with surfaces, Boufadel and his team, which includes faculty from Johns Hopkins University, the University of Cincinnati and the University of Pittsburgh, plan to provide even more precision with their simulations.

"XSEDE has opened a new universe for us," he said.

This study was funded by the National Science Foundation Rapid Response Research grant program (CBET 2028271). Computations on Comet were funded by XSEDE (TG-BCS190002).

 

About San Diego Supercomputer Center

The San Diego Supercomputer Center at UC San Diego is considered a leader in advanced computation and all aspects of "Big Data," including data integration and storage, performance modeling, data mining and predictive analytics, software development and more. SDSC provides resources, services and expertise to the national research community, including academia, industry and government. SDSC supports hundreds of multidisciplinary programs spanning various domains, from astrophysics and bioinformatics to environmental sciences and health IT.