Model shows how air conditioning influences COVID-19 transmission

Model shows how air conditioning influences COVID-19 transmission
Researchers used sophisticated computer models to simulate the influence of air conditioning on air flow and aerosol concentrations inside a restaurant in China where a documented COVID-19 outbreak occurred last spring. Photo by Han Liu

Feb. 9 (UPI) -- Scientists have looked at the spread of COVID-19 within a variety of indoor settings, including restaurants, offices, hospitals and elevators, but there is still plenty they don't understand about the ways complex airflow patterns influence viral transmission.

In a study published Tuesday in the journal Physics of Fluids, researchers used sophisticated computer simulations to study how cold air from air conditioning interacts with warm air plumes emanating from dining tables in a restaurant.


The simulations showed how the mixture of warm and cold air can influence the flow of airborne virus particles.

"Our simulation captures various physical factors, including turbulent air flow, thermal effect, aerosol transport in turbulence, limited filtration efficiency of air conditioners, as well as the complex geometry of the space, all of which play a role in airborne transmission," study co-author Jiarong Hong, physicist at the University of Minnesota, said in a press release.

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While several studies have analyzed the possible movement patterns of COVID-19 particles through a variety of indoor environs, from bathrooms to stairwells, most model hypothetical settings and situations.

This new study used their simulations to make sense of a documented COVID-19 outbreak at a restaurant in China.


Through modeling, researchers were able to figure out why some people in the restaurant became infected and others did not.

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"[The study] was enabled by advanced computational tools used in our simulation, which can capture the complex flows and aerosol transport and other multi-physics factors involved in a realistic setting," Hong said.

The model's predicted regions of high aerosol exposure overlapped with the positions of diners that later tested positive for the virus.

The research revealed two modes of viral transmission that have been missed by previous modeling efforts.

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Simulations showed air rising from beneath a table yields areas of high aerosol exposure. The model also showed air conditioners with poor filtration abilities produce what researchers dubbed "reentry aerosols."

"Our work highlights the need for more preventive measures, such as shielding more properly underneath the table and improving the filtration efficiency of air conditioners," Hong said.

"More importantly, our research demonstrates the capability and value of high-fidelity computer simulation tools for airborne infection risk assessment and the development of effective preventive measures," Hong said.

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