Decision tools for schools using continuous indoor air quality monitors: a case study of CO₂ in Boston Public Schools

Indoor environments in schools affect children's health and learning, but without indoor air quality (IAQ) monitoring, staff have limited data to inform interventions. We aimed to demonstrate the utility of comprehensive real-time classroom IAQ monitoring for informing interventions and investments in schools.

We created analytical datasets of classroom carbon dioxide (CO₂) from a groundbreaking network of 3659 commercial IAQ monitors installed across a U.S. school district. We analysed patterns and trends in 125 school buildings over the 2022-2023 school year. Working with Boston Public Schools (BPS) staff, we co-created visualisations suitable for school decision-making and for research.

Over the school year, 245 million CO₂ measurements were recorded. The average school-day CO₂ concentration was 841 ppm (SD: 405 ppm) and the 99.9th percentile of daily maxima was 5080 ppm. Concentrations varied by over an order of magnitude within and between schools. Elevated levels occurred in all buildings, although schools with central mechanical ventilation had lower concentrations and variability than schools without. We show multiple visualisations of monitoring data using threshold-based exposure metrics.

Our academic-school partnership enabled actionable research in support of IAQ improvements. The heterogeneity of CO₂ levels across BPS classrooms and between schools underscores the need for continuous classroom-level monitoring and demand-controlled ventilation. Results and protocols are generalisable to other schools and researchers. Our work paves the road for future studies of IAQ and student health and learning.

Boston University Initiative on Cities, Boston University School of Public Health, National Institutes of Health, National Science Foundation.