2021 Yes https://www.sciencedirect.com/science/article/pii/S0013935121008549?via%3Dihub Di Gilio, Alessia Europe Observational Epidemiology Study Modeling Teachers Elementary (K-5) Middle/Jr High (6-8) Carbon dioxide (CO2) COVID-19 SARS-COV-2 transmission risk mitigation Indoor ventilation conditions School re-opening NDIR sensor The development and implementation of tailored ventilation protocol including the real time visualization of CO2 levels allowed to depict better scenariosAn overall improvement of CO2 levels was indeed registered for all classrooms where teachers were compliant and helpful in the management of the air ventilation strategy. Therefore, this study reports the first evidence-based measures demonstrating that, with the exception of few environments affected by structural limits, the real-time visualization and monitoring of CO2 concentrations allowes effective air exchanges to be implemented and contributes to prevent SARS-CoV-2 transmission.