2021 Yes https://www.mdpi.com/1660-4601/18/18/9712 Lovec, Vesna Europe Observational Elementary (K-5) Temperature Humidity Carbon Dioxide (CO2) Kindergartens IAQ COVID-19 Thermal comfort The results have shown a better indoor air quality in kindergartens during the pandemic, mostly due to ventilation protocols and almost imperceptibly changed indoor air temperature. The COVID-19 pandemic affected air quality in kindergarten classrooms in Slovenia by reducing the average carbon dioxide concentration when children were present in classrooms by 30%.