Experimental investigation to verify if excessive plastic sheeting shielding produce micro clusters of SARS-CoV-2

Abstract

We experimentally investigated indoor air ventilation using the CO2 tracer technique to verify the infection cluster of SARS-CoV-2 that erupted at an office space. Multi-placed observations revealed extremely low air change rates (0.1/h) at the site. The local infection clusters were observed several meters away from a door that is the only ventilation in the office, which suggests a negative effect of plastic sheeting shielding. The thermo-fluid simulation showed that the plastic sheet blocked the airflow and trapped the exhaled air in each partition cell. As risk suppression methods, improving air ventilation by opening windows and using fans were verified, and significant improvements (10-28/h) were observed for each partition cells.

Prevention of SARS-CoV-2 airborne transmission in a workplace based on CO2 sensor network

“…Measurement using sensor networks is effective in detecting such a ventilation bias. In addition, the observed bias of CO 2 is more complex in rooms with larger sizes, complex geometries, and various uses, 2,11 and this study agrees with previously reported results.…”

“…Although there is still a possibility of confounding variables owing to the relatively small number of infections in Japan since October 2021, the fact that no infections have been confirmed since the adoption of improved ventilation Condition 2 and the results of our previous study 2 indicate that the outbreaks of the infection clusters share the feature of a ACH of less than 2 /h. In addition, where the ACH was improved to 2 or more /h, no evidence of a second infection cluster has been identified.…”

“…1 In addition, the inappropriate use of plastic sheeting for preventing droplet infection has caused clusters of infectious diseases and threatened workplace safety. 2 To avoid such risks, the use of CO2 sensors to control indoor air quality has attracted significant attention. [3][4][5][6][7] The measurement of indoor CO2 concentration (referring to exhaled air) is considered an effective method for indirect risk management to ensure that exhaled aerosol particles containing SARS-CoV-2 do not remain indoors.…”

“…In addition, the ventilation performance is not uniform for floors with large areas and complex layouts. 2,11 Therefore, a systematic evaluation should be conducted by analyzing the time series of data from sensors arranged in a network, and these results can be used to improve ventilation and reduce transmission risks.…”

Investigation of air change rate and aerosol behavior during an outbreak of COVID-19 in a geriatric care facility

“…Ventilation plays an important role in controlling aerosol transmission of coronavirus disease (COVID-19), and mass transmission of COVID-19 has been reported in poorly ventilated areas [1, 2]. Menzies et al [3] analyzed determinants of the risk of secondary transmission of tuberculosis and measles in various hospital settings and reported that an average of less than two ventilation cycles per hour (air change rate per hour; ACR) in the examination room was significantly associated with tuberculin conversion.…”