WASHINGTON, January 26, 2021 – The location of air filters and outdoor facilities in confined spaces, such as elevators, has a major impact on the spread of airborne viruses. In Physics of wetness, by AIP Publishing, researchers from the University of Nicosia in Cyprus show that while air purifiers would be expected to help, they may increase their distribution.
Air quality in small areas can deteriorate rapidly without ventilation. However, adding ventilation will increase the rate at which air, possibly full of viruses, can circulate in the small space. Elevator manufacturers have added air purifiers to address this problem, but the systems have not been designed to account for their impact on overall air circulation.
Air purifiers use ultraviolet radiation to kill viruses and other microbes, but they also circulate air, rub it in and expel clean air. This contributes to overall circulation, an aspect that has not been evaluated in previous research.
Previous work by scientists has shown that saliva droplets can travel 18 feet in five seconds when an uninjured person coughs. The authors extended the same model to study the effects of face and weather masks.
Researchers calculated for a 3D space equivalent to an elevator capable of holding five. Mild coughing was simulated at one place in the area, and airways and outlets were placed in several locations to study their effect on circulation. An air purifier was also introduced into the simulation.
“We measured the effect of air circulation on the spread of airborne viruses and showed that installing an air purifier inside an elevator significantly alters air circulation but does not eliminate air circulation,” the spokesman said. author Dimitris Drikakis.
The researchers found that the risk of airborne virus transmission is lowest for low ventilation levels.
“This is due to a smaller flow mix within the elevator,” said author Talib Dbouk. “Regulatory authorities should therefore define the minimum ventilation required depending on the type of building.”
The study looked at the location of an air cleaner, considering only the incoming air and the air associated with the cleaning machine, but not the approach inside the air- cleanser that kills the virus. Even with an air purifier in place, airborne virus spread remains important.
“Our findings show that installing an air purifier could increase droplet dispersion,” Drikakis said. “The air intake inside the purifier equipment causes a circulating flow that can contribute to the transport of contaminated saliva droplets in the cabin.”
The observed effect increases with the number of infectious people in the elevator. Limiting the number of people allowed in an elevator would reduce the spread of the virus as would better design of air purifiers and ventilators.
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The article “On the spread of airborne virus in elevators and confined spaces” is written by Talib Dbouk and Dimitris Drikakis. The article will appear in Physics of wetness on January 26, 2021 (DOI: 10.1063 / 5.0038180). After that date, it can be accessed at https: /
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