Is it Safe to Reopen Theaters During the COVID-19 Pandemic?

Abstract

Severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) is spreading globally, and its high transmission speed and mortality rate are severely interfering with people’s normal lives and the economy. Governments are now reopening their economies; however, the opening of theaters has been delayed, owing to their (often) crowded audiences and potentially higher infection risk. To determine whether it is safe to reopen theaters, in this study, the transport of contaminants released by an infected person in a theater hall with an overhead air supply system is analyzed numerically. The infection risks are calculated for occupants at various distances from the infected person in different directions and with/without wearing masks based on a revised Wells-Riley model, and under different supply air states and locations of the infected person. The results show that, first, the probabilities of infection in return air with filtration and all-fresh-air operations are decreased by 39.8 and 55.6%, respectively, as compared when the return air is not filtered. Second, the probabilities of infection for audiences sitting nine seats away from the infected person on the right, right-back, and back sides are 84.9–92.3%, 37.3–74.0%, and 36.3–72.0% lower, respectively, than those for audiences sitting one-seat away from the infected person. In addition, sitting in separate rows can reduce the maximum probability by 7.4–68.3%. Third, the probability of infection can be reduced by 93.7% after all the audiences wear masks with efficiencies of 75%. Fourth, the probability of infection can be controlled under a relatively safe range even though the quanta emission rate is 30 or 50 quanta/h, and even with two infected people in unfavorable seats. Thus, theaters can be safely reopened under return air filtration or all fresh air operations, and when audiences are sitting in separate seats and wearing masks.

Impact of natural ventilation on exposure to SARS-CoV 2 in indoor/semi-indoor terraces using CO2 concentrations as a proxy

“…The application of CFD models to study the exposure to SARS-CoV 2 in several real environments during COVID19 pandemic has been already addressed in the recent literature: in a grocery store [ 30 ], in a restaurant [ 31 ] or in a waiting room [ 32 ]. In addition, the local risk level has been analyzed in a classroom [ 33 ] or in a theater hall [ 34 ]. However, in these studies, natural ventilation has not been considered or not accurately considered despite being indoor/semi-indoor environments.…”

Airborne transmission of the Delta variant of SARS-CoV-2 in an auditorium

“…Researchers resort to various fluid mechanics models to assess the transport and dispersion of viral particles. An example is the Computational Fluid Dynamics (CFD) method, which has been used to study airborne disease transmission in enclosed environments, including aircraft cabins [ 22 ], buses [ 23 ], movie theatre [ 24 ], and multi-family residential buildings [ 25 ]. Alternative models, such as the zonal airflow network model, originally developed to assess heat and moisture content inside buildings [ 26 ], have been used to simulate the movement of contaminant and airborne pathogens in enclosed environments.…”

“…Maintaining a social distance, either by one or two meters (WHO, 2020), or by six-feet [ 21 ], have been practiced widely, although its efficacy remain debated [ 40 ]. Social distancing in high-occupancy buildings is practiced in the form of reduced seating capacity, such as audience seating in separate rows or in every other seat, to allow more distances between occupants [ 24 ]. Body-temperature checking, a mean to identify and isolate persons with fever, a common symptom of COVID-19, is regarded as a key public health response in the management of public facilities [ 41 ].…”

Control strategy of fan filter units in cleanroom considering of the moving personnel

“…Because the diffusion and transport properties of particles less than 2 µm were similar to those of passive gases [13,14], particles were regarded as gaseous pollutants, which were passively transported. The Boussinesq model was employed to consider the buoyancy effect [15].…”