#E0064 Role of excessive plastic sheeting on the formation of SARS-CoV-2 in a closed indoor environment
Role of excessive plastic sheeting on the formation of SARS-CoV-2 in a closed indoor environment
Several studies have reported that the risk of indoor aerosol infection is higher if people come into close contact with diagnosed or potentially infected people in a relatively confined space. Recently, sterilizing fingers to prevent contact infection and wearing a mask to prevent droplet infection have been applied as protective measures in offices.
This study investigated the ventilatory effects of plastic shields at a SARS-CoV-2 cluster site. Air ventilation in each compartment and the effects of the plastic shields were investigated using the CO2 tracer technique and dry-ice emissions. The observed changes in the CO2 concentration in each compartment were compared using a time-series analysis technique.
In this study, 11 of the 30 individuals who worked in the same air-conditioned office in Miyagi, Japan, were infected with COVID-19. The office was divided into five compartments by plastic shields. According to interviews with the supervisor, the workers were engaged in paperwork, but extensive face-to-face contact occurred because of the nature of their operations. Some workers wore urethane or cloth masks. The office is not equipped with a mechanical ventilation system or additional ventilation tools, such as a room fan. Therefore, natural ventilation can only be achieved by opening the door and windows.
The windows were not frequently opened, and three air conditioners were attached to the ceiling and set at approximately 20°C (28°C in summer), which the Ministry of the Environment recommends for winter. The office was not equipped with a high-efficiency particulate air filter or non-woven filter air purifier; the only effective filter was a plastic mesh in the air conditioner to remove coarse dust. The indoor CO2 concentration was increased by scattering crumbled dry ice on the floor without ventilation.
The air change rate in each compartment was estimated using the observed decrease in CO2 concentration. The difference in the air change rate was small, suggesting that the opening of the windows improved ventilation in each compartment. The ventilation was enhanced following the installation of room fans to blow air out of the windows. Ventilation is considered an important factor in preventing airborne transmission because COVID-19 outbreaks have largely occurred in poor ventilated spaces.
This study, highlights that though a space-filling plastic shield may seem like reassuring at first glance, it may impede ventilation and increase the risk of airborne infection. However, if plastic shields hinder ventilation capacity, the risk of airborne infection by droplet nuclei must be considered.
Link to the original journal article:
https://www.jstage.jst.go.jp/article/eohp/5/1/5_2022-0024-OA/_article
Title of the paper:
Ventilatory effects of excessive plastic sheeting on the formation of SARS-Cov-2 in a closed indoor environment
Authors:
Yo Ishigaki, Yuto Kawauchi, Shinji Yokogawa, Akira Saito, Hiroko Kitamura, Takashi Moritake
