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Stickiness of COVID Particles Reduces Airborne Concentration in Supermarkets

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

Published May 6, 2021

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 air-borne 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

By Kimberly Bruch and Cynthia Dillon, SDSC Communications

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 at the same time vaccinations are being administered, ongoing virus mitigation strategies remain on the CDC’s list of guidelines. In the meantime, a team of environmental engineers recently used Comet at the San Diego Supercomputer Center at UC 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 (NJIT), 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 greatly reduces the maximum concentration of suspended particles in the air by as much as 50 percent.

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

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

“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 1 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 include even more precision with their simulations.

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

This study was funded by 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,” which include 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 a wide variety of domains, from astrophysics and bioinformatics to environmental sciences and health IT.