CO2 concentration visualization for COVID-19 infection prevention in concert halls

Objectives: For preventing coronavirus disease 2019 (COVID-19) clusters, avoiding the three C’s, which are closed spaces with poor ventilation, crowded places with many people, and close contact for conversation, is important. The CO2 concentration in a room indicates the ventilation status, number of persons present in the room, and their kinetic strength or activity intensity. The real-time monitoring of CO2 concentration in a room will enable instantaneously confirming whether ventilation is sufficient. Methods: This study investigated monitoring CO2 concentration in real time during a concert and instantly indicating the measurement results on a display. Results: The average CO2 concentration during the performance was confirmed to be 505.6 ppm with the maximum value 575 ppm, and these values were in line with the estimated value given by the Ventilation Simulator designed by the Occupational Hygiene and Ergonomics Section of the Japan Society for Occupational Health. The CO2 concentration visualization has the benefit of providing a sense of security to the concert audience, musicians, and concert organizing staff during the performance. Conclusion: For preventing COVID-19 clusters, it is important to take multiple and comprehensive countermeasures considering concert event-specific infection routes; visualizing CO2 concentration is one effective preventative measure against airborne (droplet nuclei) infection. The CO2 concentration visualization based on prior estimation is expected to become part of the standard operational procedure of concert venues