AsianScientist (Feb. 7, 2022) – As COVID-19 continues to sweep through the globe, scientists are uncovering new insights into how the disease is transmitted in urban areas. A Singapore University of Technology and Design (SUTD) team has modeled the impact of ventilation—or lack thereof—on viral spread in worker dormitories, publishing the findings in Sustainable Cities and Society.
In 2020, Singapore witnessed a surge in COVID-19 prevalence among workers residing in dormitories around the city-state. Although several factors can contribute to an outbreak, densely packed spaces are especially notorious for driving up case tallies. That is further aggravated by the fact that the virus causing COVID-19 spreads by airborne transmission.
Given the virus’ mode of transmission, proper ventilation is vital to mitigating disease spread. Without good wind flow, infectious respiratory droplets can linger in the vicinity, increasing the risk of these viral particles infiltrating other individuals. However, creating well-ventilated spaces needs an in-depth examination of building designs from window placement to street layouts.
To better understand the factors influencing air flow in Singapore’s urban spaces, SUTD Faculty Fellow Dr. Zheng Kai and colleagues simulated droplet spread in two local dormitories using computational fluid dynamics software. This tool allowed the team to track the flow of air and corresponding droplet transmission within the dormitories as well as across neighborhoods, identifying possible measures for improving ventilation in the buildings. .
The first dormitory, an 11-story building, had rooms with two windows on opposite sides. According to the researchers, such a setup allowed for cross-ventilation, where the wind can blow in through one opening and out through another. Interestingly, computer simulations of a sneeze from one infected person showed that this wind flow easily carried light droplets out of the room.
However, larger droplets still circulated indoors, going from bed to bed before they were blown out of the room. In some rooms facing away from Singapore’s natural wind direction, the stagnant air led to even lighter particles lingering for over 10 minutes. In that situation, increasing the distance between beds did not help with airflow or reducing transmission risk.
The second dormitory lacked suitable openings for natural ventilation, and the windows were blocked by adjacent buildings. Moreover, it was situated along a row of closely packed structures, which created a canyon-like environment with stagnant air. With little wind flowing through the building, Zheng’s team found that sneeze particles stayed in rooms for at least a few minutes.
The researchers highlighted that indoor ventilation may be improved by orienting building openings in line with Singapore’s typical wind direction, from north-east to south. Other design considerations could involve adding wind scoops, which direct outside air to flow indoors, and placing electric fans in strategic locations to blow indoor air out through the windows.
“Blanket measures are not useful and not necessarily effective at curbing viral transmission. Instead, we can design for cross-ventilation in the rooms wherever possible,” said Zheng. “Future directions will look at developing a simple risk quantification tool based on ventilation and possible viral transmission.”
The article can be found at: Zheng et al. (2021) Ventilation in worker dormitories and its impact on the spread of respiratory droplets.
Source: Singapore University of Technology and Design; Photo: Marcus Lenk/Unsplash.
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