2024 No Indoor air quality in classrooms: Environmental measures and effective ventilation rate modeling in urban elementary schools https://doi.org/10.1016/j.buildenv.2018.03.040 Johnson, David L. North America Observational Exposure Modeling Students Elementary (K-5) Particulate Matter (PM) Carbon Dioxide (CO2) Carbon Monoxide (CO) Nitrogen Dioxide (NO2) Volatile Organic Compounds (VOCs) Temperature Humidity Other Ventilation Schools Indoor air quality Transient mass balance IAQ in 12 Oklahoma elementary schools was assessed using seasonal 24-h sampling of PM, CO₂, CO, NO₂, VOCs, formaldehyde, temp, and humidity. A transient mass balance model estimated effective fresh air ventilation. Many rooms lacked sufficient ventilation, suggesting seasonal HVAC variation needs policy attention. 2018