2021 Yes https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8624555/ Zaeh, Sandra E North America Exposure Study Students Temperature Carbon Dioxide (CO2) Carbon Monoxide (CO) School Indoor air quality Renovation In 29 urban public schools, air quality (CO₂, PM₂.₅, CO, temperature) was measured across seasons before and after renovations. Renovated schools had significantly improved CO₂, PM₂.₅, and CO levels. Renovation may benefit students in under-resourced communities.