2023 Yes https://www.mdpi.com/1660-4601/20/18/6757 Sanchez-Fernandez, Ana Europe Observational Students Elementary (K-5) Middle/Jr High (6-8) High School (9-12) Carbon Dioxide (CO2) Particulate Matter (PM) Temperature Humidity Atmospheric pressure CO2 ventilation strategies monitoring Indoor air quality Pollution Concluding results have allowed us to determine the maximum number of students allowed in a closed room to maintain CO2 levels at normal concentrations and the time needed to reduce these CO2 levels depending on the ventilation strategy adopted. Moreover, it has been discussed how surrounding school conditions (pollution or noise) and the building isolation are impacting the final IAQ in the classrooms studied.